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postgres/src/backend/optimizer/util/clauses.c
Tom Lane d2ef7758d2 Fix constant-folding of ROW(...) IS [NOT] NULL with composite fields. 
The SQL standard appears to specify that IS [NOT] NULL's tests of field
nullness are non-recursive, ie, we shouldn't consider that a composite
field with value ROW(NULL,NULL) is null for this purpose.
ExecEvalNullTest got this right, but eval_const_expressions did not,
leading to weird inconsistencies depending on whether the expression
was such that the planner could apply constant folding.

Also, adjust the docs to mention that IS [NOT] DISTINCT FROM NULL can be
used as a substitute test if a simple null check is wanted for a rowtype
argument.  That motivated reordering things so that IS [NOT] DISTINCT FROM
is described before IS [NOT] NULL.  In HEAD, I went a bit further and added
a table showing all the comparison-related predicates.

Per bug #14235.  Back-patch to all supported branches, since it's certainly
undesirable that constant-folding should change the semantics.

Report and patch by Andrew Gierth; assorted wordsmithing and revised
regression test cases by me.

Report: <20160708024746.1410.57282@wrigleys.postgresql.org>
2016-07-26 15:25:02 -04:00

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/*-------------------------------------------------------------------------
*
* clauses.c
* routines to manipulate qualification clauses
*
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/optimizer/util/clauses.c
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
* Andrew Yu Nov 3, 1994 clause.c and clauses.c combined
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_language.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "executor/functions.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/planmain.h"
#include "optimizer/prep.h"
#include "optimizer/var.h"
#include "parser/analyze.h"
#include "parser/parse_agg.h"
#include "parser/parse_coerce.h"
#include "parser/parse_func.h"
#include "rewrite/rewriteManip.h"
#include "tcop/tcopprot.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
typedef struct
{
PlannerInfo *root;
AggClauseCosts *costs;
} count_agg_clauses_context;
typedef struct
{
ParamListInfo boundParams;
PlannerInfo *root;
List *active_fns;
Node *case_val;
bool estimate;
} eval_const_expressions_context;
typedef struct
{
int nargs;
List *args;
int *usecounts;
} substitute_actual_parameters_context;
typedef struct
{
int nargs;
List *args;
int sublevels_up;
} substitute_actual_srf_parameters_context;
typedef struct
{
char *proname;
char *prosrc;
} inline_error_callback_arg;
static bool contain_agg_clause_walker(Node *node, void *context);
static bool count_agg_clauses_walker(Node *node,
count_agg_clauses_context *context);
static bool find_window_functions_walker(Node *node, WindowFuncLists *lists);
static bool expression_returns_set_rows_walker(Node *node, double *count);
static bool contain_subplans_walker(Node *node, void *context);
static bool contain_mutable_functions_walker(Node *node, void *context);
static bool contain_volatile_functions_walker(Node *node, void *context);
static bool contain_volatile_functions_not_nextval_walker(Node *node, void *context);
static bool contain_nonstrict_functions_walker(Node *node, void *context);
static bool contain_leaked_vars_walker(Node *node, void *context);
static Relids find_nonnullable_rels_walker(Node *node, bool top_level);
static List *find_nonnullable_vars_walker(Node *node, bool top_level);
static bool is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK);
static Node *eval_const_expressions_mutator(Node *node,
eval_const_expressions_context *context);
static List *simplify_or_arguments(List *args,
eval_const_expressions_context *context,
bool *haveNull, bool *forceTrue);
static List *simplify_and_arguments(List *args,
eval_const_expressions_context *context,
bool *haveNull, bool *forceFalse);
static Node *simplify_boolean_equality(Oid opno, List *args);
static Expr *simplify_function(Oid funcid,
Oid result_type, int32 result_typmod,
Oid result_collid, Oid input_collid, List **args_p,
bool funcvariadic, bool process_args, bool allow_non_const,
eval_const_expressions_context *context);
static List *expand_function_arguments(List *args, Oid result_type,
HeapTuple func_tuple);
static List *reorder_function_arguments(List *args, HeapTuple func_tuple);
static List *add_function_defaults(List *args, HeapTuple func_tuple);
static List *fetch_function_defaults(HeapTuple func_tuple);
static void recheck_cast_function_args(List *args, Oid result_type,
HeapTuple func_tuple);
static Expr *evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
Oid result_collid, Oid input_collid, List *args,
bool funcvariadic,
HeapTuple func_tuple,
eval_const_expressions_context *context);
static Expr *inline_function(Oid funcid, Oid result_type, Oid result_collid,
Oid input_collid, List *args,
bool funcvariadic,
HeapTuple func_tuple,
eval_const_expressions_context *context);
static Node *substitute_actual_parameters(Node *expr, int nargs, List *args,
int *usecounts);
static Node *substitute_actual_parameters_mutator(Node *node,
substitute_actual_parameters_context *context);
static void sql_inline_error_callback(void *arg);
static Expr *evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod,
Oid result_collation);
static Query *substitute_actual_srf_parameters(Query *expr,
int nargs, List *args);
static Node *substitute_actual_srf_parameters_mutator(Node *node,
substitute_actual_srf_parameters_context *context);
static bool tlist_matches_coltypelist(List *tlist, List *coltypelist);
/*****************************************************************************
* OPERATOR clause functions
*****************************************************************************/
/*
* make_opclause
* Creates an operator clause given its operator info, left operand
* and right operand (pass NULL to create single-operand clause),
* and collation info.
*/
Expr *
make_opclause(Oid opno, Oid opresulttype, bool opretset,
Expr *leftop, Expr *rightop,
Oid opcollid, Oid inputcollid)
{
OpExpr *expr = makeNode(OpExpr);
expr->opno = opno;
expr->opfuncid = InvalidOid;
expr->opresulttype = opresulttype;
expr->opretset = opretset;
expr->opcollid = opcollid;
expr->inputcollid = inputcollid;
if (rightop)
expr->args = list_make2(leftop, rightop);
else
expr->args = list_make1(leftop);
expr->location = -1;
return (Expr *) expr;
}
/*
* get_leftop
*
* Returns the left operand of a clause of the form (op expr expr)
* or (op expr)
*/
Node *
get_leftop(const Expr *clause)
{
const OpExpr *expr = (const OpExpr *) clause;
if (expr->args != NIL)
return linitial(expr->args);
else
return NULL;
}
/*
* get_rightop
*
* Returns the right operand in a clause of the form (op expr expr).
* NB: result will be NULL if applied to a unary op clause.
*/
Node *
get_rightop(const Expr *clause)
{
const OpExpr *expr = (const OpExpr *) clause;
if (list_length(expr->args) >= 2)
return lsecond(expr->args);
else
return NULL;
}
/*****************************************************************************
* NOT clause functions
*****************************************************************************/
/*
* not_clause
*
* Returns t iff this is a 'not' clause: (NOT expr).
*/
bool
not_clause(Node *clause)
{
return (clause != NULL &&
IsA(clause, BoolExpr) &&
((BoolExpr *) clause)->boolop == NOT_EXPR);
}
/*
* make_notclause
*
* Create a 'not' clause given the expression to be negated.
*/
Expr *
make_notclause(Expr *notclause)
{
BoolExpr *expr = makeNode(BoolExpr);
expr->boolop = NOT_EXPR;
expr->args = list_make1(notclause);
expr->location = -1;
return (Expr *) expr;
}
/*
* get_notclausearg
*
* Retrieve the clause within a 'not' clause
*/
Expr *
get_notclausearg(Expr *notclause)
{
return linitial(((BoolExpr *) notclause)->args);
}
/*****************************************************************************
* OR clause functions
*****************************************************************************/
/*
* or_clause
*
* Returns t iff the clause is an 'or' clause: (OR { expr }).
*/
bool
or_clause(Node *clause)
{
return (clause != NULL &&
IsA(clause, BoolExpr) &&
((BoolExpr *) clause)->boolop == OR_EXPR);
}
/*
* make_orclause
*
* Creates an 'or' clause given a list of its subclauses.
*/
Expr *
make_orclause(List *orclauses)
{
BoolExpr *expr = makeNode(BoolExpr);
expr->boolop = OR_EXPR;
expr->args = orclauses;
expr->location = -1;
return (Expr *) expr;
}
/*****************************************************************************
* AND clause functions
*****************************************************************************/
/*
* and_clause
*
* Returns t iff its argument is an 'and' clause: (AND { expr }).
*/
bool
and_clause(Node *clause)
{
return (clause != NULL &&
IsA(clause, BoolExpr) &&
((BoolExpr *) clause)->boolop == AND_EXPR);
}
/*
* make_andclause
*
* Creates an 'and' clause given a list of its subclauses.
*/
Expr *
make_andclause(List *andclauses)
{
BoolExpr *expr = makeNode(BoolExpr);
expr->boolop = AND_EXPR;
expr->args = andclauses;
expr->location = -1;
return (Expr *) expr;
}
/*
* make_and_qual
*
* Variant of make_andclause for ANDing two qual conditions together.
* Qual conditions have the property that a NULL nodetree is interpreted
* as 'true'.
*
* NB: this makes no attempt to preserve AND/OR flatness; so it should not
* be used on a qual that has already been run through prepqual.c.
*/
Node *
make_and_qual(Node *qual1, Node *qual2)
{
if (qual1 == NULL)
return qual2;
if (qual2 == NULL)
return qual1;
return (Node *) make_andclause(list_make2(qual1, qual2));
}
/*
* Sometimes (such as in the input of ExecQual), we use lists of expression
* nodes with implicit AND semantics.
*
* These functions convert between an AND-semantics expression list and the
* ordinary representation of a boolean expression.
*
* Note that an empty list is considered equivalent to TRUE.
*/
Expr *
make_ands_explicit(List *andclauses)
{
if (andclauses == NIL)
return (Expr *) makeBoolConst(true, false);
else if (list_length(andclauses) == 1)
return (Expr *) linitial(andclauses);
else
return make_andclause(andclauses);
}
List *
make_ands_implicit(Expr *clause)
{
/*
* NB: because the parser sets the qual field to NULL in a query that has
* no WHERE clause, we must consider a NULL input clause as TRUE, even
* though one might more reasonably think it FALSE. Grumble. If this
* causes trouble, consider changing the parser's behavior.
*/
if (clause == NULL)
return NIL; /* NULL -> NIL list == TRUE */
else if (and_clause((Node *) clause))
return ((BoolExpr *) clause)->args;
else if (IsA(clause, Const) &&
!((Const *) clause)->constisnull &&
DatumGetBool(((Const *) clause)->constvalue))
return NIL; /* constant TRUE input -> NIL list */
else
return list_make1(clause);
}
/*****************************************************************************
* Aggregate-function clause manipulation
*****************************************************************************/
/*
* contain_agg_clause
* Recursively search for Aggref/GroupingFunc nodes within a clause.
*
* Returns true if any aggregate found.
*
* This does not descend into subqueries, and so should be used only after
* reduction of sublinks to subplans, or in contexts where it's known there
* are no subqueries. There mustn't be outer-aggregate references either.
*
* (If you want something like this but able to deal with subqueries,
* see rewriteManip.c's contain_aggs_of_level().)
*/
bool
contain_agg_clause(Node *clause)
{
return contain_agg_clause_walker(clause, NULL);
}
static bool
contain_agg_clause_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, Aggref))
{
Assert(((Aggref *) node)->agglevelsup == 0);
return true; /* abort the tree traversal and return true */
}
if (IsA(node, GroupingFunc))
{
Assert(((GroupingFunc *) node)->agglevelsup == 0);
return true; /* abort the tree traversal and return true */
}
Assert(!IsA(node, SubLink));
return expression_tree_walker(node, contain_agg_clause_walker, context);
}
/*
* count_agg_clauses
* Recursively count the Aggref nodes in an expression tree, and
* accumulate other cost information about them too.
*
* Note: this also checks for nested aggregates, which are an error.
*
* We not only count the nodes, but estimate their execution costs, and
* attempt to estimate the total space needed for their transition state
* values if all are evaluated in parallel (as would be done in a HashAgg
* plan). See AggClauseCosts for the exact set of statistics collected.
*
* NOTE that the counts/costs are ADDED to those already in *costs ... so
* the caller is responsible for zeroing the struct initially.
*
* This does not descend into subqueries, and so should be used only after
* reduction of sublinks to subplans, or in contexts where it's known there
* are no subqueries. There mustn't be outer-aggregate references either.
*/
void
count_agg_clauses(PlannerInfo *root, Node *clause, AggClauseCosts *costs)
{
count_agg_clauses_context context;
context.root = root;
context.costs = costs;
(void) count_agg_clauses_walker(clause, &context);
}
static bool
count_agg_clauses_walker(Node *node, count_agg_clauses_context *context)
{
if (node == NULL)
return false;
if (IsA(node, Aggref))
{
Aggref *aggref = (Aggref *) node;
AggClauseCosts *costs = context->costs;
HeapTuple aggTuple;
Form_pg_aggregate aggform;
Oid aggtransfn;
Oid aggfinalfn;
Oid aggtranstype;
int32 aggtransspace;
QualCost argcosts;
Oid inputTypes[FUNC_MAX_ARGS];
int numArguments;
Assert(aggref->agglevelsup == 0);
/*
* Fetch info about aggregate from pg_aggregate. Note it's correct to
* ignore the moving-aggregate variant, since what we're concerned
* with here is aggregates not window functions.
*/
aggTuple = SearchSysCache1(AGGFNOID,
ObjectIdGetDatum(aggref->aggfnoid));
if (!HeapTupleIsValid(aggTuple))
elog(ERROR, "cache lookup failed for aggregate %u",
aggref->aggfnoid);
aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
aggtransfn = aggform->aggtransfn;
aggfinalfn = aggform->aggfinalfn;
aggtranstype = aggform->aggtranstype;
aggtransspace = aggform->aggtransspace;
ReleaseSysCache(aggTuple);
/* count it; note ordered-set aggs always have nonempty aggorder */
costs->numAggs++;
if (aggref->aggorder != NIL || aggref->aggdistinct != NIL)
costs->numOrderedAggs++;
/* add component function execution costs to appropriate totals */
costs->transCost.per_tuple += get_func_cost(aggtransfn) * cpu_operator_cost;
if (OidIsValid(aggfinalfn))
costs->finalCost += get_func_cost(aggfinalfn) * cpu_operator_cost;
/* also add the input expressions' cost to per-input-row costs */
cost_qual_eval_node(&argcosts, (Node *) aggref->args, context->root);
costs->transCost.startup += argcosts.startup;
costs->transCost.per_tuple += argcosts.per_tuple;
/*
* Add any filter's cost to per-input-row costs.
*
* XXX Ideally we should reduce input expression costs according to
* filter selectivity, but it's not clear it's worth the trouble.
*/
if (aggref->aggfilter)
{
cost_qual_eval_node(&argcosts, (Node *) aggref->aggfilter,
context->root);
costs->transCost.startup += argcosts.startup;
costs->transCost.per_tuple += argcosts.per_tuple;
}
/*
* If there are direct arguments, treat their evaluation cost like the
* cost of the finalfn.
*/
if (aggref->aggdirectargs)
{
cost_qual_eval_node(&argcosts, (Node *) aggref->aggdirectargs,
context->root);
costs->transCost.startup += argcosts.startup;
costs->finalCost += argcosts.per_tuple;
}
/* extract argument types (ignoring any ORDER BY expressions) */
numArguments = get_aggregate_argtypes(aggref, inputTypes);
/* resolve actual type of transition state, if polymorphic */
aggtranstype = resolve_aggregate_transtype(aggref->aggfnoid,
aggtranstype,
inputTypes,
numArguments);
/*
* If the transition type is pass-by-value then it doesn't add
* anything to the required size of the hashtable. If it is
* pass-by-reference then we have to add the estimated size of the
* value itself, plus palloc overhead.
*/
if (!get_typbyval(aggtranstype))
{
int32 avgwidth;
/* Use average width if aggregate definition gave one */
if (aggtransspace > 0)
avgwidth = aggtransspace;
else
{
/*
* If transition state is of same type as first aggregated
* input, assume it's the same typmod (same width) as well.
* This works for cases like MAX/MIN and is probably somewhat
* reasonable otherwise.
*/
int numdirectargs = list_length(aggref->aggdirectargs);
int32 aggtranstypmod;
if (numArguments > numdirectargs &&
aggtranstype == inputTypes[numdirectargs])
aggtranstypmod = exprTypmod((Node *) linitial(aggref->args));
else
aggtranstypmod = -1;
avgwidth = get_typavgwidth(aggtranstype, aggtranstypmod);
}
avgwidth = MAXALIGN(avgwidth);
costs->transitionSpace += avgwidth + 2 * sizeof(void *);
}
else if (aggtranstype == INTERNALOID)
{
/*
* INTERNAL transition type is a special case: although INTERNAL
* is pass-by-value, it's almost certainly being used as a pointer
* to some large data structure. The aggregate definition can
* provide an estimate of the size. If it doesn't, then we assume
* ALLOCSET_DEFAULT_INITSIZE, which is a good guess if the data is
* being kept in a private memory context, as is done by
* array_agg() for instance.
*/
if (aggtransspace > 0)
costs->transitionSpace += aggtransspace;
else
costs->transitionSpace += ALLOCSET_DEFAULT_INITSIZE;
}
/*
* We assume that the parser checked that there are no aggregates (of
* this level anyway) in the aggregated arguments, direct arguments,
* or filter clause. Hence, we need not recurse into any of them. (If
* either the parser or the planner screws up on this point, the
* executor will still catch it; see ExecInitExpr.)
*/
return false;
}
Assert(!IsA(node, SubLink));
return expression_tree_walker(node, count_agg_clauses_walker,
(void *) context);
}
/*****************************************************************************
* Window-function clause manipulation
*****************************************************************************/
/*
* contain_window_function
* Recursively search for WindowFunc nodes within a clause.
*
* Since window functions don't have level fields, but are hard-wired to
* be associated with the current query level, this is just the same as
* rewriteManip.c's function.
*/
bool
contain_window_function(Node *clause)
{
return contain_windowfuncs(clause);
}
/*
* find_window_functions
* Locate all the WindowFunc nodes in an expression tree, and organize
* them by winref ID number.
*
* Caller must provide an upper bound on the winref IDs expected in the tree.
*/
WindowFuncLists *
find_window_functions(Node *clause, Index maxWinRef)
{
WindowFuncLists *lists = palloc(sizeof(WindowFuncLists));
lists->numWindowFuncs = 0;
lists->maxWinRef = maxWinRef;
lists->windowFuncs = (List **) palloc0((maxWinRef + 1) * sizeof(List *));
(void) find_window_functions_walker(clause, lists);
return lists;
}
static bool
find_window_functions_walker(Node *node, WindowFuncLists *lists)
{
if (node == NULL)
return false;
if (IsA(node, WindowFunc))
{
WindowFunc *wfunc = (WindowFunc *) node;
/* winref is unsigned, so one-sided test is OK */
if (wfunc->winref > lists->maxWinRef)
elog(ERROR, "WindowFunc contains out-of-range winref %u",
wfunc->winref);
lists->windowFuncs[wfunc->winref] =
lappend(lists->windowFuncs[wfunc->winref], wfunc);
lists->numWindowFuncs++;
/*
* We assume that the parser checked that there are no window
* functions in the arguments or filter clause. Hence, we need not
* recurse into them. (If either the parser or the planner screws up
* on this point, the executor will still catch it; see ExecInitExpr.)
*/
return false;
}
Assert(!IsA(node, SubLink));
return expression_tree_walker(node, find_window_functions_walker,
(void *) lists);
}
/*****************************************************************************
* Support for expressions returning sets
*****************************************************************************/
/*
* expression_returns_set_rows
* Estimate the number of rows returned by a set-returning expression.
* The result is 1 if there are no set-returning functions.
*
* We use the product of the rowcount estimates of all the functions in
* the given tree (this corresponds to the behavior of ExecMakeFunctionResult
* for nested set-returning functions).
*
* Note: keep this in sync with expression_returns_set() in nodes/nodeFuncs.c.
*/
double
expression_returns_set_rows(Node *clause)
{
double result = 1;
(void) expression_returns_set_rows_walker(clause, &result);
return clamp_row_est(result);
}
static bool
expression_returns_set_rows_walker(Node *node, double *count)
{
if (node == NULL)
return false;
if (IsA(node, FuncExpr))
{
FuncExpr *expr = (FuncExpr *) node;
if (expr->funcretset)
*count *= get_func_rows(expr->funcid);
}
if (IsA(node, OpExpr))
{
OpExpr *expr = (OpExpr *) node;
if (expr->opretset)
{
set_opfuncid(expr);
*count *= get_func_rows(expr->opfuncid);
}
}
/* Avoid recursion for some cases that can't return a set */
if (IsA(node, Aggref))
return false;
if (IsA(node, WindowFunc))
return false;
if (IsA(node, DistinctExpr))
return false;
if (IsA(node, NullIfExpr))
return false;
if (IsA(node, ScalarArrayOpExpr))
return false;
if (IsA(node, BoolExpr))
return false;
if (IsA(node, SubLink))
return false;
if (IsA(node, SubPlan))
return false;
if (IsA(node, AlternativeSubPlan))
return false;
if (IsA(node, ArrayExpr))
return false;
if (IsA(node, RowExpr))
return false;
if (IsA(node, RowCompareExpr))
return false;
if (IsA(node, CoalesceExpr))
return false;
if (IsA(node, MinMaxExpr))
return false;
if (IsA(node, XmlExpr))
return false;
return expression_tree_walker(node, expression_returns_set_rows_walker,
(void *) count);
}
/*
* tlist_returns_set_rows
* Estimate the number of rows returned by a set-returning targetlist.
* The result is 1 if there are no set-returning functions.
*
* Here, the result is the largest rowcount estimate of any of the tlist's
* expressions, not the product as you would get from naively applying
* expression_returns_set_rows() to the whole tlist. The behavior actually
* implemented by ExecTargetList produces a number of rows equal to the least
* common multiple of the expression rowcounts, so that the product would be
* a worst-case estimate that is typically not realistic. Taking the max as
* we do here is a best-case estimate that might not be realistic either,
* but it's probably closer for typical usages. We don't try to compute the
* actual LCM because we're working with very approximate estimates, so their
* LCM would be unduly noisy.
*/
double
tlist_returns_set_rows(List *tlist)
{
double result = 1;
ListCell *lc;
foreach(lc, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
double colresult;
colresult = expression_returns_set_rows((Node *) tle->expr);
if (result < colresult)
result = colresult;
}
return result;
}
/*****************************************************************************
* Subplan clause manipulation
*****************************************************************************/
/*
* contain_subplans
* Recursively search for subplan nodes within a clause.
*
* If we see a SubLink node, we will return TRUE. This is only possible if
* the expression tree hasn't yet been transformed by subselect.c. We do not
* know whether the node will produce a true subplan or just an initplan,
* but we make the conservative assumption that it will be a subplan.
*
* Returns true if any subplan found.
*/
bool
contain_subplans(Node *clause)
{
return contain_subplans_walker(clause, NULL);
}
static bool
contain_subplans_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, SubPlan) ||
IsA(node, AlternativeSubPlan) ||
IsA(node, SubLink))
return true; /* abort the tree traversal and return true */
return expression_tree_walker(node, contain_subplans_walker, context);
}
/*****************************************************************************
* Check clauses for mutable functions
*****************************************************************************/
/*
* contain_mutable_functions
* Recursively search for mutable functions within a clause.
*
* Returns true if any mutable function (or operator implemented by a
* mutable function) is found. This test is needed so that we don't
* mistakenly think that something like "WHERE random() < 0.5" can be treated
* as a constant qualification.
*
* We will recursively look into Query nodes (i.e., SubLink sub-selects)
* but not into SubPlans. See comments for contain_volatile_functions().
*/
bool
contain_mutable_functions(Node *clause)
{
return contain_mutable_functions_walker(clause, NULL);
}
static bool
contain_mutable_functions_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, FuncExpr))
{
FuncExpr *expr = (FuncExpr *) node;
if (func_volatile(expr->funcid) != PROVOLATILE_IMMUTABLE)
return true;
/* else fall through to check args */
}
else if (IsA(node, OpExpr))
{
OpExpr *expr = (OpExpr *) node;
set_opfuncid(expr);
if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
return true;
/* else fall through to check args */
}
else if (IsA(node, DistinctExpr))
{
DistinctExpr *expr = (DistinctExpr *) node;
set_opfuncid((OpExpr *) expr); /* rely on struct equivalence */
if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
return true;
/* else fall through to check args */
}
else if (IsA(node, NullIfExpr))
{
NullIfExpr *expr = (NullIfExpr *) node;
set_opfuncid((OpExpr *) expr); /* rely on struct equivalence */
if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
return true;
/* else fall through to check args */
}
else if (IsA(node, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
set_sa_opfuncid(expr);
if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
return true;
/* else fall through to check args */
}
else if (IsA(node, CoerceViaIO))
{
CoerceViaIO *expr = (CoerceViaIO *) node;
Oid iofunc;
Oid typioparam;
bool typisvarlena;
/* check the result type's input function */
getTypeInputInfo(expr->resulttype,
&iofunc, &typioparam);
if (func_volatile(iofunc) != PROVOLATILE_IMMUTABLE)
return true;
/* check the input type's output function */
getTypeOutputInfo(exprType((Node *) expr->arg),
&iofunc, &typisvarlena);
if (func_volatile(iofunc) != PROVOLATILE_IMMUTABLE)
return true;
/* else fall through to check args */
}
else if (IsA(node, ArrayCoerceExpr))
{
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
if (OidIsValid(expr->elemfuncid) &&
func_volatile(expr->elemfuncid) != PROVOLATILE_IMMUTABLE)
return true;
/* else fall through to check args */
}
else if (IsA(node, RowCompareExpr))
{
RowCompareExpr *rcexpr = (RowCompareExpr *) node;
ListCell *opid;
foreach(opid, rcexpr->opnos)
{
if (op_volatile(lfirst_oid(opid)) != PROVOLATILE_IMMUTABLE)
return true;
}
/* else fall through to check args */
}
else if (IsA(node, Query))
{
/* Recurse into subselects */
return query_tree_walker((Query *) node,
contain_mutable_functions_walker,
context, 0);
}
return expression_tree_walker(node, contain_mutable_functions_walker,
context);
}
/*****************************************************************************
* Check clauses for volatile functions
*****************************************************************************/
/*
* contain_volatile_functions
* Recursively search for volatile functions within a clause.
*
* Returns true if any volatile function (or operator implemented by a
* volatile function) is found. This test prevents, for example,
* invalid conversions of volatile expressions into indexscan quals.
*
* We will recursively look into Query nodes (i.e., SubLink sub-selects)
* but not into SubPlans. This is a bit odd, but intentional. If we are
* looking at a SubLink, we are probably deciding whether a query tree
* transformation is safe, and a contained sub-select should affect that;
* for example, duplicating a sub-select containing a volatile function
* would be bad. However, once we've got to the stage of having SubPlans,
* subsequent planning need not consider volatility within those, since
* the executor won't change its evaluation rules for a SubPlan based on
* volatility.
*/
bool
contain_volatile_functions(Node *clause)
{
return contain_volatile_functions_walker(clause, NULL);
}
bool
contain_volatile_functions_not_nextval(Node *clause)
{
return contain_volatile_functions_not_nextval_walker(clause, NULL);
}
/*
* General purpose code for checking expression volatility.
*
* Special purpose code for use in COPY is almost identical to this,
* so any changes here may also be needed in other contain_volatile...
* functions.
*/
static bool
contain_volatile_functions_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, FuncExpr))
{
FuncExpr *expr = (FuncExpr *) node;
if (func_volatile(expr->funcid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, OpExpr))
{
OpExpr *expr = (OpExpr *) node;
set_opfuncid(expr);
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, DistinctExpr))
{
DistinctExpr *expr = (DistinctExpr *) node;
set_opfuncid((OpExpr *) expr); /* rely on struct equivalence */
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, NullIfExpr))
{
NullIfExpr *expr = (NullIfExpr *) node;
set_opfuncid((OpExpr *) expr); /* rely on struct equivalence */
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
set_sa_opfuncid(expr);
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, CoerceViaIO))
{
CoerceViaIO *expr = (CoerceViaIO *) node;
Oid iofunc;
Oid typioparam;
bool typisvarlena;
/* check the result type's input function */
getTypeInputInfo(expr->resulttype,
&iofunc, &typioparam);
if (func_volatile(iofunc) == PROVOLATILE_VOLATILE)
return true;
/* check the input type's output function */
getTypeOutputInfo(exprType((Node *) expr->arg),
&iofunc, &typisvarlena);
if (func_volatile(iofunc) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, ArrayCoerceExpr))
{
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
if (OidIsValid(expr->elemfuncid) &&
func_volatile(expr->elemfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, RowCompareExpr))
{
/* RowCompare probably can't have volatile ops, but check anyway */
RowCompareExpr *rcexpr = (RowCompareExpr *) node;
ListCell *opid;
foreach(opid, rcexpr->opnos)
{
if (op_volatile(lfirst_oid(opid)) == PROVOLATILE_VOLATILE)
return true;
}
/* else fall through to check args */
}
else if (IsA(node, Query))
{
/* Recurse into subselects */
return query_tree_walker((Query *) node,
contain_volatile_functions_walker,
context, 0);
}
return expression_tree_walker(node, contain_volatile_functions_walker,
context);
}
/*
* Special purpose version of contain_volatile_functions for use in COPY
*/
static bool
contain_volatile_functions_not_nextval_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, FuncExpr))
{
FuncExpr *expr = (FuncExpr *) node;
/*
* For this case only, we want to ignore the volatility of the
* nextval() function, since some callers want this.
*/
if (expr->funcid != F_NEXTVAL_OID &&
func_volatile(expr->funcid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, OpExpr))
{
OpExpr *expr = (OpExpr *) node;
set_opfuncid(expr);
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, DistinctExpr))
{
DistinctExpr *expr = (DistinctExpr *) node;
set_opfuncid((OpExpr *) expr); /* rely on struct equivalence */
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, NullIfExpr))
{
NullIfExpr *expr = (NullIfExpr *) node;
set_opfuncid((OpExpr *) expr); /* rely on struct equivalence */
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
set_sa_opfuncid(expr);
if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, CoerceViaIO))
{
CoerceViaIO *expr = (CoerceViaIO *) node;
Oid iofunc;
Oid typioparam;
bool typisvarlena;
/* check the result type's input function */
getTypeInputInfo(expr->resulttype,
&iofunc, &typioparam);
if (func_volatile(iofunc) == PROVOLATILE_VOLATILE)
return true;
/* check the input type's output function */
getTypeOutputInfo(exprType((Node *) expr->arg),
&iofunc, &typisvarlena);
if (func_volatile(iofunc) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, ArrayCoerceExpr))
{
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
if (OidIsValid(expr->elemfuncid) &&
func_volatile(expr->elemfuncid) == PROVOLATILE_VOLATILE)
return true;
/* else fall through to check args */
}
else if (IsA(node, RowCompareExpr))
{
/* RowCompare probably can't have volatile ops, but check anyway */
RowCompareExpr *rcexpr = (RowCompareExpr *) node;
ListCell *opid;
foreach(opid, rcexpr->opnos)
{
if (op_volatile(lfirst_oid(opid)) == PROVOLATILE_VOLATILE)
return true;
}
/* else fall through to check args */
}
return expression_tree_walker(node, contain_volatile_functions_not_nextval_walker,
context);
}
/*****************************************************************************
* Check clauses for nonstrict functions
*****************************************************************************/
/*
* contain_nonstrict_functions
* Recursively search for nonstrict functions within a clause.
*
* Returns true if any nonstrict construct is found --- ie, anything that
* could produce non-NULL output with a NULL input.
*
* The idea here is that the caller has verified that the expression contains
* one or more Var or Param nodes (as appropriate for the caller's need), and
* now wishes to prove that the expression result will be NULL if any of these
* inputs is NULL. If we return false, then the proof succeeded.
*/
bool
contain_nonstrict_functions(Node *clause)
{
return contain_nonstrict_functions_walker(clause, NULL);
}
static bool
contain_nonstrict_functions_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (IsA(node, Aggref))
{
/* an aggregate could return non-null with null input */
return true;
}
if (IsA(node, WindowFunc))
{
/* a window function could return non-null with null input */
return true;
}
if (IsA(node, ArrayRef))
{
/* array assignment is nonstrict, but subscripting is strict */
if (((ArrayRef *) node)->refassgnexpr != NULL)
return true;
/* else fall through to check args */
}
if (IsA(node, FuncExpr))
{
FuncExpr *expr = (FuncExpr *) node;
if (!func_strict(expr->funcid))
return true;
/* else fall through to check args */
}
if (IsA(node, OpExpr))
{
OpExpr *expr = (OpExpr *) node;
set_opfuncid(expr);
if (!func_strict(expr->opfuncid))
return true;
/* else fall through to check args */
}
if (IsA(node, DistinctExpr))
{
/* IS DISTINCT FROM is inherently non-strict */
return true;
}
if (IsA(node, NullIfExpr))
return true;
if (IsA(node, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
if (!is_strict_saop(expr, false))
return true;
/* else fall through to check args */
}
if (IsA(node, BoolExpr))
{
BoolExpr *expr = (BoolExpr *) node;
switch (expr->boolop)
{
case AND_EXPR:
case OR_EXPR:
/* AND, OR are inherently non-strict */
return true;
default:
break;
}
}
if (IsA(node, SubLink))
{
/* In some cases a sublink might be strict, but in general not */
return true;
}
if (IsA(node, SubPlan))
return true;
if (IsA(node, AlternativeSubPlan))
return true;
/* ArrayCoerceExpr is strict at the array level, regardless of elemfunc */
if (IsA(node, FieldStore))
return true;
if (IsA(node, CaseExpr))
return true;
if (IsA(node, ArrayExpr))
return true;
if (IsA(node, RowExpr))
return true;
if (IsA(node, RowCompareExpr))
return true;
if (IsA(node, CoalesceExpr))
return true;
if (IsA(node, MinMaxExpr))
return true;
if (IsA(node, XmlExpr))
return true;
if (IsA(node, NullTest))
return true;
if (IsA(node, BooleanTest))
return true;
return expression_tree_walker(node, contain_nonstrict_functions_walker,
context);
}
/*****************************************************************************
* Check clauses for Vars passed to non-leakproof functions
*****************************************************************************/
/*
* contain_leaked_vars
* Recursively scan a clause to discover whether it contains any Var
* nodes (of the current query level) that are passed as arguments to
* leaky functions.
*
* Returns true if the clause contains any non-leakproof functions that are
* passed Var nodes of the current query level, and which might therefore leak
* data. Qualifiers from outside a security_barrier view that might leak data
* in this way should not be pushed down into the view in case the contents of
* tuples intended to be filtered out by the view are revealed by the leaky
* functions.
*/
bool
contain_leaked_vars(Node *clause)
{
return contain_leaked_vars_walker(clause, NULL);
}
static bool
contain_leaked_vars_walker(Node *node, void *context)
{
if (node == NULL)
return false;
switch (nodeTag(node))
{
case T_Var:
case T_Const:
case T_Param:
case T_ArrayExpr:
case T_NamedArgExpr:
case T_BoolExpr:
case T_RelabelType:
case T_CaseExpr:
case T_CaseTestExpr:
case T_RowExpr:
case T_MinMaxExpr:
case T_NullTest:
case T_BooleanTest:
case T_List:
/*
* We know these node types don't contain function calls; but
* something further down in the node tree might.
*/
break;
case T_FuncExpr:
{
FuncExpr *expr = (FuncExpr *) node;
if (!get_func_leakproof(expr->funcid) &&
contain_var_clause((Node *) expr->args))
return true;
}
break;
case T_OpExpr:
case T_DistinctExpr: /* struct-equivalent to OpExpr */
case T_NullIfExpr: /* struct-equivalent to OpExpr */
{
OpExpr *expr = (OpExpr *) node;
set_opfuncid(expr);
if (!get_func_leakproof(expr->opfuncid) &&
contain_var_clause((Node *) expr->args))
return true;
}
break;
case T_ScalarArrayOpExpr:
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
set_sa_opfuncid(expr);
if (!get_func_leakproof(expr->opfuncid) &&
contain_var_clause((Node *) expr->args))
return true;
}
break;
case T_CoerceViaIO:
{
CoerceViaIO *expr = (CoerceViaIO *) node;
Oid funcid;
Oid ioparam;
bool leakproof;
bool varlena;
/*
* Data may be leaked if either the input or the output
* function is leaky.
*/
getTypeInputInfo(exprType((Node *) expr->arg),
&funcid, &ioparam);
leakproof = get_func_leakproof(funcid);
/*
* If the input function is leakproof, then check the output
* function.
*/
if (leakproof)
{
getTypeOutputInfo(expr->resulttype, &funcid, &varlena);
leakproof = get_func_leakproof(funcid);
}
if (!leakproof &&
contain_var_clause((Node *) expr->arg))
return true;
}
break;
case T_ArrayCoerceExpr:
{
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
Oid funcid;
Oid ioparam;
bool leakproof;
bool varlena;
/*
* Data may be leaked if either the input or the output
* function is leaky.
*/
getTypeInputInfo(exprType((Node *) expr->arg),
&funcid, &ioparam);
leakproof = get_func_leakproof(funcid);
/*
* If the input function is leakproof, then check the output
* function.
*/
if (leakproof)
{
getTypeOutputInfo(expr->resulttype, &funcid, &varlena);
leakproof = get_func_leakproof(funcid);
}
if (!leakproof &&
contain_var_clause((Node *) expr->arg))
return true;
}
break;
case T_RowCompareExpr:
{
RowCompareExpr *rcexpr = (RowCompareExpr *) node;
ListCell *opid;
ListCell *larg;
ListCell *rarg;
/*
* Check the comparison function and arguments passed to it
* for each pair of row elements.
*/
forthree(opid, rcexpr->opnos,
larg, rcexpr->largs,
rarg, rcexpr->rargs)
{
Oid funcid = get_opcode(lfirst_oid(opid));
if (!get_func_leakproof(funcid) &&
(contain_var_clause((Node *) lfirst(larg)) ||
contain_var_clause((Node *) lfirst(rarg))))
return true;
}
}
break;
case T_CurrentOfExpr:
/*
* WHERE CURRENT OF doesn't contain function calls. Moreover, it
* is important that this can be pushed down into a
* security_barrier view, since the planner must always generate
* a TID scan when CURRENT OF is present -- c.f. cost_tidscan.
*/
return false;
default:
/*
* If we don't recognize the node tag, assume it might be leaky.
* This prevents an unexpected security hole if someone adds a new
* node type that can call a function.
*/
return true;
}
return expression_tree_walker(node, contain_leaked_vars_walker,
context);
}
/*
* find_nonnullable_rels
* Determine which base rels are forced nonnullable by given clause.
*
* Returns the set of all Relids that are referenced in the clause in such
* a way that the clause cannot possibly return TRUE if any of these Relids
* is an all-NULL row. (It is OK to err on the side of conservatism; hence
* the analysis here is simplistic.)
*
* The semantics here are subtly different from contain_nonstrict_functions:
* that function is concerned with NULL results from arbitrary expressions,
* but here we assume that the input is a Boolean expression, and wish to
* see if NULL inputs will provably cause a FALSE-or-NULL result. We expect
* the expression to have been AND/OR flattened and converted to implicit-AND
* format.
*
* Note: this function is largely duplicative of find_nonnullable_vars().
* The reason not to simplify this function into a thin wrapper around
* find_nonnullable_vars() is that the tested conditions really are different:
* a clause like "t1.v1 IS NOT NULL OR t1.v2 IS NOT NULL" does not prove
* that either v1 or v2 can't be NULL, but it does prove that the t1 row
* as a whole can't be all-NULL.
*
* top_level is TRUE while scanning top-level AND/OR structure; here, showing
* the result is either FALSE or NULL is good enough. top_level is FALSE when
* we have descended below a NOT or a strict function: now we must be able to
* prove that the subexpression goes to NULL.
*
* We don't use expression_tree_walker here because we don't want to descend
* through very many kinds of nodes; only the ones we can be sure are strict.
*/
Relids
find_nonnullable_rels(Node *clause)
{
return find_nonnullable_rels_walker(clause, true);
}
static Relids
find_nonnullable_rels_walker(Node *node, bool top_level)
{
Relids result = NULL;
ListCell *l;
if (node == NULL)
return NULL;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup == 0)
result = bms_make_singleton(var->varno);
}
else if (IsA(node, List))
{
/*
* At top level, we are examining an implicit-AND list: if any of the
* arms produces FALSE-or-NULL then the result is FALSE-or-NULL. If
* not at top level, we are examining the arguments of a strict
* function: if any of them produce NULL then the result of the
* function must be NULL. So in both cases, the set of nonnullable
* rels is the union of those found in the arms, and we pass down the
* top_level flag unmodified.
*/
foreach(l, (List *) node)
{
result = bms_join(result,
find_nonnullable_rels_walker(lfirst(l),
top_level));
}
}
else if (IsA(node, FuncExpr))
{
FuncExpr *expr = (FuncExpr *) node;
if (func_strict(expr->funcid))
result = find_nonnullable_rels_walker((Node *) expr->args, false);
}
else if (IsA(node, OpExpr))
{
OpExpr *expr = (OpExpr *) node;
set_opfuncid(expr);
if (func_strict(expr->opfuncid))
result = find_nonnullable_rels_walker((Node *) expr->args, false);
}
else if (IsA(node, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
if (is_strict_saop(expr, true))
result = find_nonnullable_rels_walker((Node *) expr->args, false);
}
else if (IsA(node, BoolExpr))
{
BoolExpr *expr = (BoolExpr *) node;
switch (expr->boolop)
{
case AND_EXPR:
/* At top level we can just recurse (to the List case) */
if (top_level)
{
result = find_nonnullable_rels_walker((Node *) expr->args,
top_level);
break;
}
/*
* Below top level, even if one arm produces NULL, the result
* could be FALSE (hence not NULL). However, if *all* the
* arms produce NULL then the result is NULL, so we can take
* the intersection of the sets of nonnullable rels, just as
* for OR. Fall through to share code.
*/
/* FALL THRU */
case OR_EXPR:
/*
* OR is strict if all of its arms are, so we can take the
* intersection of the sets of nonnullable rels for each arm.
* This works for both values of top_level.
*/
foreach(l, expr->args)
{
Relids subresult;
subresult = find_nonnullable_rels_walker(lfirst(l),
top_level);
if (result == NULL) /* first subresult? */
result = subresult;
else
result = bms_int_members(result, subresult);
/*
* If the intersection is empty, we can stop looking. This
* also justifies the test for first-subresult above.
*/
if (bms_is_empty(result))
break;
}
break;
case NOT_EXPR:
/* NOT will return null if its arg is null */
result = find_nonnullable_rels_walker((Node *) expr->args,
false);
break;
default:
elog(ERROR, "unrecognized boolop: %d", (int) expr->boolop);
break;
}
}
else if (IsA(node, RelabelType))
{
RelabelType *expr = (RelabelType *) node;
result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, CoerceViaIO))
{
/* not clear this is useful, but it can't hurt */
CoerceViaIO *expr = (CoerceViaIO *) node;
result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, ArrayCoerceExpr))
{
/* ArrayCoerceExpr is strict at the array level */
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, ConvertRowtypeExpr))
{
/* not clear this is useful, but it can't hurt */
ConvertRowtypeExpr *expr = (ConvertRowtypeExpr *) node;
result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, CollateExpr))
{
CollateExpr *expr = (CollateExpr *) node;
result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, NullTest))
{
/* IS NOT NULL can be considered strict, but only at top level */
NullTest *expr = (NullTest *) node;
if (top_level && expr->nulltesttype == IS_NOT_NULL && !expr->argisrow)
result = find_nonnullable_rels_walker((Node *) expr->arg, false);
}
else if (IsA(node, BooleanTest))
{
/* Boolean tests that reject NULL are strict at top level */
BooleanTest *expr = (BooleanTest *) node;
if (top_level &&
(expr->booltesttype == IS_TRUE ||
expr->booltesttype == IS_FALSE ||
expr->booltesttype == IS_NOT_UNKNOWN))
result = find_nonnullable_rels_walker((Node *) expr->arg, false);
}
else if (IsA(node, PlaceHolderVar))
{
PlaceHolderVar *phv = (PlaceHolderVar *) node;
result = find_nonnullable_rels_walker((Node *) phv->phexpr, top_level);
}
return result;
}
/*
* find_nonnullable_vars
* Determine which Vars are forced nonnullable by given clause.
*
* Returns a list of all level-zero Vars that are referenced in the clause in
* such a way that the clause cannot possibly return TRUE if any of these Vars
* is NULL. (It is OK to err on the side of conservatism; hence the analysis
* here is simplistic.)
*
* The semantics here are subtly different from contain_nonstrict_functions:
* that function is concerned with NULL results from arbitrary expressions,
* but here we assume that the input is a Boolean expression, and wish to
* see if NULL inputs will provably cause a FALSE-or-NULL result. We expect
* the expression to have been AND/OR flattened and converted to implicit-AND
* format.
*
* The result is a palloc'd List, but we have not copied the member Var nodes.
* Also, we don't bother trying to eliminate duplicate entries.
*
* top_level is TRUE while scanning top-level AND/OR structure; here, showing
* the result is either FALSE or NULL is good enough. top_level is FALSE when
* we have descended below a NOT or a strict function: now we must be able to
* prove that the subexpression goes to NULL.
*
* We don't use expression_tree_walker here because we don't want to descend
* through very many kinds of nodes; only the ones we can be sure are strict.
*/
List *
find_nonnullable_vars(Node *clause)
{
return find_nonnullable_vars_walker(clause, true);
}
static List *
find_nonnullable_vars_walker(Node *node, bool top_level)
{
List *result = NIL;
ListCell *l;
if (node == NULL)
return NIL;
if (IsA(node, Var))
{
Var *var = (Var *) node;
if (var->varlevelsup == 0)
result = list_make1(var);
}
else if (IsA(node, List))
{
/*
* At top level, we are examining an implicit-AND list: if any of the
* arms produces FALSE-or-NULL then the result is FALSE-or-NULL. If
* not at top level, we are examining the arguments of a strict
* function: if any of them produce NULL then the result of the
* function must be NULL. So in both cases, the set of nonnullable
* vars is the union of those found in the arms, and we pass down the
* top_level flag unmodified.
*/
foreach(l, (List *) node)
{
result = list_concat(result,
find_nonnullable_vars_walker(lfirst(l),
top_level));
}
}
else if (IsA(node, FuncExpr))
{
FuncExpr *expr = (FuncExpr *) node;
if (func_strict(expr->funcid))
result = find_nonnullable_vars_walker((Node *) expr->args, false);
}
else if (IsA(node, OpExpr))
{
OpExpr *expr = (OpExpr *) node;
set_opfuncid(expr);
if (func_strict(expr->opfuncid))
result = find_nonnullable_vars_walker((Node *) expr->args, false);
}
else if (IsA(node, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
if (is_strict_saop(expr, true))
result = find_nonnullable_vars_walker((Node *) expr->args, false);
}
else if (IsA(node, BoolExpr))
{
BoolExpr *expr = (BoolExpr *) node;
switch (expr->boolop)
{
case AND_EXPR:
/* At top level we can just recurse (to the List case) */
if (top_level)
{
result = find_nonnullable_vars_walker((Node *) expr->args,
top_level);
break;
}
/*
* Below top level, even if one arm produces NULL, the result
* could be FALSE (hence not NULL). However, if *all* the
* arms produce NULL then the result is NULL, so we can take
* the intersection of the sets of nonnullable vars, just as
* for OR. Fall through to share code.
*/
/* FALL THRU */
case OR_EXPR:
/*
* OR is strict if all of its arms are, so we can take the
* intersection of the sets of nonnullable vars for each arm.
* This works for both values of top_level.
*/
foreach(l, expr->args)
{
List *subresult;
subresult = find_nonnullable_vars_walker(lfirst(l),
top_level);
if (result == NIL) /* first subresult? */
result = subresult;
else
result = list_intersection(result, subresult);
/*
* If the intersection is empty, we can stop looking. This
* also justifies the test for first-subresult above.
*/
if (result == NIL)
break;
}
break;
case NOT_EXPR:
/* NOT will return null if its arg is null */
result = find_nonnullable_vars_walker((Node *) expr->args,
false);
break;
default:
elog(ERROR, "unrecognized boolop: %d", (int) expr->boolop);
break;
}
}
else if (IsA(node, RelabelType))
{
RelabelType *expr = (RelabelType *) node;
result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, CoerceViaIO))
{
/* not clear this is useful, but it can't hurt */
CoerceViaIO *expr = (CoerceViaIO *) node;
result = find_nonnullable_vars_walker((Node *) expr->arg, false);
}
else if (IsA(node, ArrayCoerceExpr))
{
/* ArrayCoerceExpr is strict at the array level */
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, ConvertRowtypeExpr))
{
/* not clear this is useful, but it can't hurt */
ConvertRowtypeExpr *expr = (ConvertRowtypeExpr *) node;
result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, CollateExpr))
{
CollateExpr *expr = (CollateExpr *) node;
result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
}
else if (IsA(node, NullTest))
{
/* IS NOT NULL can be considered strict, but only at top level */
NullTest *expr = (NullTest *) node;
if (top_level && expr->nulltesttype == IS_NOT_NULL && !expr->argisrow)
result = find_nonnullable_vars_walker((Node *) expr->arg, false);
}
else if (IsA(node, BooleanTest))
{
/* Boolean tests that reject NULL are strict at top level */
BooleanTest *expr = (BooleanTest *) node;
if (top_level &&
(expr->booltesttype == IS_TRUE ||
expr->booltesttype == IS_FALSE ||
expr->booltesttype == IS_NOT_UNKNOWN))
result = find_nonnullable_vars_walker((Node *) expr->arg, false);
}
else if (IsA(node, PlaceHolderVar))
{
PlaceHolderVar *phv = (PlaceHolderVar *) node;
result = find_nonnullable_vars_walker((Node *) phv->phexpr, top_level);
}
return result;
}
/*
* find_forced_null_vars
* Determine which Vars must be NULL for the given clause to return TRUE.
*
* This is the complement of find_nonnullable_vars: find the level-zero Vars
* that must be NULL for the clause to return TRUE. (It is OK to err on the
* side of conservatism; hence the analysis here is simplistic. In fact,
* we only detect simple "var IS NULL" tests at the top level.)
*
* The result is a palloc'd List, but we have not copied the member Var nodes.
* Also, we don't bother trying to eliminate duplicate entries.
*/
List *
find_forced_null_vars(Node *node)
{
List *result = NIL;
Var *var;
ListCell *l;
if (node == NULL)
return NIL;
/* Check single-clause cases using subroutine */
var = find_forced_null_var(node);
if (var)
{
result = list_make1(var);
}
/* Otherwise, handle AND-conditions */
else if (IsA(node, List))
{
/*
* At top level, we are examining an implicit-AND list: if any of the
* arms produces FALSE-or-NULL then the result is FALSE-or-NULL.
*/
foreach(l, (List *) node)
{
result = list_concat(result,
find_forced_null_vars(lfirst(l)));
}
}
else if (IsA(node, BoolExpr))
{
BoolExpr *expr = (BoolExpr *) node;
/*
* We don't bother considering the OR case, because it's fairly
* unlikely anyone would write "v1 IS NULL OR v1 IS NULL". Likewise,
* the NOT case isn't worth expending code on.
*/
if (expr->boolop == AND_EXPR)
{
/* At top level we can just recurse (to the List case) */
result = find_forced_null_vars((Node *) expr->args);
}
}
return result;
}
/*
* find_forced_null_var
* Return the Var forced null by the given clause, or NULL if it's
* not an IS NULL-type clause. For success, the clause must enforce
* *only* nullness of the particular Var, not any other conditions.
*
* This is just the single-clause case of find_forced_null_vars(), without
* any allowance for AND conditions. It's used by initsplan.c on individual
* qual clauses. The reason for not just applying find_forced_null_vars()
* is that if an AND of an IS NULL clause with something else were to somehow
* survive AND/OR flattening, initsplan.c might get fooled into discarding
* the whole clause when only the IS NULL part of it had been proved redundant.
*/
Var *
find_forced_null_var(Node *node)
{
if (node == NULL)
return NULL;
if (IsA(node, NullTest))
{
/* check for var IS NULL */
NullTest *expr = (NullTest *) node;
if (expr->nulltesttype == IS_NULL && !expr->argisrow)
{
Var *var = (Var *) expr->arg;
if (var && IsA(var, Var) &&
var->varlevelsup == 0)
return var;
}
}
else if (IsA(node, BooleanTest))
{
/* var IS UNKNOWN is equivalent to var IS NULL */
BooleanTest *expr = (BooleanTest *) node;
if (expr->booltesttype == IS_UNKNOWN)
{
Var *var = (Var *) expr->arg;
if (var && IsA(var, Var) &&
var->varlevelsup == 0)
return var;
}
}
return NULL;
}
/*
* Can we treat a ScalarArrayOpExpr as strict?
*
* If "falseOK" is true, then a "false" result can be considered strict,
* else we need to guarantee an actual NULL result for NULL input.
*
* "foo op ALL array" is strict if the op is strict *and* we can prove
* that the array input isn't an empty array. We can check that
* for the cases of an array constant and an ARRAY[] construct.
*
* "foo op ANY array" is strict in the falseOK sense if the op is strict.
* If not falseOK, the test is the same as for "foo op ALL array".
*/
static bool
is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK)
{
Node *rightop;
/* The contained operator must be strict. */
set_sa_opfuncid(expr);
if (!func_strict(expr->opfuncid))
return false;
/* If ANY and falseOK, that's all we need to check. */
if (expr->useOr && falseOK)
return true;
/* Else, we have to see if the array is provably non-empty. */
Assert(list_length(expr->args) == 2);
rightop = (Node *) lsecond(expr->args);
if (rightop && IsA(rightop, Const))
{
Datum arraydatum = ((Const *) rightop)->constvalue;
bool arrayisnull = ((Const *) rightop)->constisnull;
ArrayType *arrayval;
int nitems;
if (arrayisnull)
return false;
arrayval = DatumGetArrayTypeP(arraydatum);
nitems = ArrayGetNItems(ARR_NDIM(arrayval), ARR_DIMS(arrayval));
if (nitems > 0)
return true;
}
else if (rightop && IsA(rightop, ArrayExpr))
{
ArrayExpr *arrayexpr = (ArrayExpr *) rightop;
if (arrayexpr->elements != NIL && !arrayexpr->multidims)
return true;
}
return false;
}
/*****************************************************************************
* Check for "pseudo-constant" clauses
*****************************************************************************/
/*
* is_pseudo_constant_clause
* Detect whether an expression is "pseudo constant", ie, it contains no
* variables of the current query level and no uses of volatile functions.
* Such an expr is not necessarily a true constant: it can still contain
* Params and outer-level Vars, not to mention functions whose results
* may vary from one statement to the next. However, the expr's value
* will be constant over any one scan of the current query, so it can be
* used as, eg, an indexscan key.
*
* CAUTION: this function omits to test for one very important class of
* not-constant expressions, namely aggregates (Aggrefs). In current usage
* this is only applied to WHERE clauses and so a check for Aggrefs would be
* a waste of cycles; but be sure to also check contain_agg_clause() if you
* want to know about pseudo-constness in other contexts. The same goes
* for window functions (WindowFuncs).
*/
bool
is_pseudo_constant_clause(Node *clause)
{
/*
* We could implement this check in one recursive scan. But since the
* check for volatile functions is both moderately expensive and unlikely
* to fail, it seems better to look for Vars first and only check for
* volatile functions if we find no Vars.
*/
if (!contain_var_clause(clause) &&
!contain_volatile_functions(clause))
return true;
return false;
}
/*
* is_pseudo_constant_clause_relids
* Same as above, except caller already has available the var membership
* of the expression; this lets us avoid the contain_var_clause() scan.
*/
bool
is_pseudo_constant_clause_relids(Node *clause, Relids relids)
{
if (bms_is_empty(relids) &&
!contain_volatile_functions(clause))
return true;
return false;
}
/*****************************************************************************
* *
* General clause-manipulating routines *
* *
*****************************************************************************/
/*
* NumRelids
* (formerly clause_relids)
*
* Returns the number of different relations referenced in 'clause'.
*/
int
NumRelids(Node *clause)
{
Relids varnos = pull_varnos(clause);
int result = bms_num_members(varnos);
bms_free(varnos);
return result;
}
/*
* CommuteOpExpr: commute a binary operator clause
*
* XXX the clause is destructively modified!
*/
void
CommuteOpExpr(OpExpr *clause)
{
Oid opoid;
Node *temp;
/* Sanity checks: caller is at fault if these fail */
if (!is_opclause(clause) ||
list_length(clause->args) != 2)
elog(ERROR, "cannot commute non-binary-operator clause");
opoid = get_commutator(clause->opno);
if (!OidIsValid(opoid))
elog(ERROR, "could not find commutator for operator %u",
clause->opno);
/*
* modify the clause in-place!
*/
clause->opno = opoid;
clause->opfuncid = InvalidOid;
/* opresulttype, opretset, opcollid, inputcollid need not change */
temp = linitial(clause->args);
linitial(clause->args) = lsecond(clause->args);
lsecond(clause->args) = temp;
}
/*
* CommuteRowCompareExpr: commute a RowCompareExpr clause
*
* XXX the clause is destructively modified!
*/
void
CommuteRowCompareExpr(RowCompareExpr *clause)
{
List *newops;
List *temp;
ListCell *l;
/* Sanity checks: caller is at fault if these fail */
if (!IsA(clause, RowCompareExpr))
elog(ERROR, "expected a RowCompareExpr");
/* Build list of commuted operators */
newops = NIL;
foreach(l, clause->opnos)
{
Oid opoid = lfirst_oid(l);
opoid = get_commutator(opoid);
if (!OidIsValid(opoid))
elog(ERROR, "could not find commutator for operator %u",
lfirst_oid(l));
newops = lappend_oid(newops, opoid);
}
/*
* modify the clause in-place!
*/
switch (clause->rctype)
{
case ROWCOMPARE_LT:
clause->rctype = ROWCOMPARE_GT;
break;
case ROWCOMPARE_LE:
clause->rctype = ROWCOMPARE_GE;
break;
case ROWCOMPARE_GE:
clause->rctype = ROWCOMPARE_LE;
break;
case ROWCOMPARE_GT:
clause->rctype = ROWCOMPARE_LT;
break;
default:
elog(ERROR, "unexpected RowCompare type: %d",
(int) clause->rctype);
break;
}
clause->opnos = newops;
/*
* Note: we need not change the opfamilies list; we assume any btree
* opfamily containing an operator will also contain its commutator.
* Collations don't change either.
*/
temp = clause->largs;
clause->largs = clause->rargs;
clause->rargs = temp;
}
/*
* Helper for eval_const_expressions: check that datatype of an attribute
* is still what it was when the expression was parsed. This is needed to
* guard against improper simplification after ALTER COLUMN TYPE. (XXX we
* may well need to make similar checks elsewhere?)
*/
static bool
rowtype_field_matches(Oid rowtypeid, int fieldnum,
Oid expectedtype, int32 expectedtypmod,
Oid expectedcollation)
{
TupleDesc tupdesc;
Form_pg_attribute attr;
/* No issue for RECORD, since there is no way to ALTER such a type */
if (rowtypeid == RECORDOID)
return true;
tupdesc = lookup_rowtype_tupdesc(rowtypeid, -1);
if (fieldnum <= 0 || fieldnum > tupdesc->natts)
{
ReleaseTupleDesc(tupdesc);
return false;
}
attr = tupdesc->attrs[fieldnum - 1];
if (attr->attisdropped ||
attr->atttypid != expectedtype ||
attr->atttypmod != expectedtypmod ||
attr->attcollation != expectedcollation)
{
ReleaseTupleDesc(tupdesc);
return false;
}
ReleaseTupleDesc(tupdesc);
return true;
}
/*--------------------
* eval_const_expressions
*
* Reduce any recognizably constant subexpressions of the given
* expression tree, for example "2 + 2" => "4". More interestingly,
* we can reduce certain boolean expressions even when they contain
* non-constant subexpressions: "x OR true" => "true" no matter what
* the subexpression x is. (XXX We assume that no such subexpression
* will have important side-effects, which is not necessarily a good
* assumption in the presence of user-defined functions; do we need a
* pg_proc flag that prevents discarding the execution of a function?)
*
* We do understand that certain functions may deliver non-constant
* results even with constant inputs, "nextval()" being the classic
* example. Functions that are not marked "immutable" in pg_proc
* will not be pre-evaluated here, although we will reduce their
* arguments as far as possible.
*
* Whenever a function is eliminated from the expression by means of
* constant-expression evaluation or inlining, we add the function to
* root->glob->invalItems. This ensures the plan is known to depend on
* such functions, even though they aren't referenced anymore.
*
* We assume that the tree has already been type-checked and contains
* only operators and functions that are reasonable to try to execute.
*
* NOTE: "root" can be passed as NULL if the caller never wants to do any
* Param substitutions nor receive info about inlined functions.
*
* NOTE: the planner assumes that this will always flatten nested AND and
* OR clauses into N-argument form. See comments in prepqual.c.
*
* NOTE: another critical effect is that any function calls that require
* default arguments will be expanded, and named-argument calls will be
* converted to positional notation. The executor won't handle either.
*--------------------
*/
Node *
eval_const_expressions(PlannerInfo *root, Node *node)
{
eval_const_expressions_context context;
if (root)
context.boundParams = root->glob->boundParams; /* bound Params */
else
context.boundParams = NULL;
context.root = root; /* for inlined-function dependencies */
context.active_fns = NIL; /* nothing being recursively simplified */
context.case_val = NULL; /* no CASE being examined */
context.estimate = false; /* safe transformations only */
return eval_const_expressions_mutator(node, &context);
}
/*--------------------
* estimate_expression_value
*
* This function attempts to estimate the value of an expression for
* planning purposes. It is in essence a more aggressive version of
* eval_const_expressions(): we will perform constant reductions that are
* not necessarily 100% safe, but are reasonable for estimation purposes.
*
* Currently the extra steps that are taken in this mode are:
* 1. Substitute values for Params, where a bound Param value has been made
* available by the caller of planner(), even if the Param isn't marked
* constant. This effectively means that we plan using the first supplied
* value of the Param.
* 2. Fold stable, as well as immutable, functions to constants.
* 3. Reduce PlaceHolderVar nodes to their contained expressions.
*--------------------
*/
Node *
estimate_expression_value(PlannerInfo *root, Node *node)
{
eval_const_expressions_context context;
context.boundParams = root->glob->boundParams; /* bound Params */
/* we do not need to mark the plan as depending on inlined functions */
context.root = NULL;
context.active_fns = NIL; /* nothing being recursively simplified */
context.case_val = NULL; /* no CASE being examined */
context.estimate = true; /* unsafe transformations OK */
return eval_const_expressions_mutator(node, &context);
}
static Node *
eval_const_expressions_mutator(Node *node,
eval_const_expressions_context *context)
{
if (node == NULL)
return NULL;
switch (nodeTag(node))
{
case T_Param:
{
Param *param = (Param *) node;
/* Look to see if we've been given a value for this Param */
if (param->paramkind == PARAM_EXTERN &&
context->boundParams != NULL &&
param->paramid > 0 &&
param->paramid <= context->boundParams->numParams)
{
ParamExternData *prm = &context->boundParams->params[param->paramid - 1];
if (OidIsValid(prm->ptype))
{
/* OK to substitute parameter value? */
if (context->estimate ||
(prm->pflags & PARAM_FLAG_CONST))
{
/*
* Return a Const representing the param value.
* Must copy pass-by-ref datatypes, since the
* Param might be in a memory context
* shorter-lived than our output plan should be.
*/
int16 typLen;
bool typByVal;
Datum pval;
Assert(prm->ptype == param->paramtype);
get_typlenbyval(param->paramtype,
&typLen, &typByVal);
if (prm->isnull || typByVal)
pval = prm->value;
else
pval = datumCopy(prm->value, typByVal, typLen);
return (Node *) makeConst(param->paramtype,
param->paramtypmod,
param->paramcollid,
(int) typLen,
pval,
prm->isnull,
typByVal);
}
}
}
/*
* Not replaceable, so just copy the Param (no need to
* recurse)
*/
return (Node *) copyObject(param);
}
case T_WindowFunc:
{
WindowFunc *expr = (WindowFunc *) node;
Oid funcid = expr->winfnoid;
List *args;
Expr *aggfilter;
HeapTuple func_tuple;
WindowFunc *newexpr;
/*
* We can't really simplify a WindowFunc node, but we mustn't
* just fall through to the default processing, because we
* have to apply expand_function_arguments to its argument
* list. That takes care of inserting default arguments and
* expanding named-argument notation.
*/
func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
if (!HeapTupleIsValid(func_tuple))
elog(ERROR, "cache lookup failed for function %u", funcid);
args = expand_function_arguments(expr->args, expr->wintype,
func_tuple);
ReleaseSysCache(func_tuple);
/* Now, recursively simplify the args (which are a List) */
args = (List *)
expression_tree_mutator((Node *) args,
eval_const_expressions_mutator,
(void *) context);
/* ... and the filter expression, which isn't */
aggfilter = (Expr *)
eval_const_expressions_mutator((Node *) expr->aggfilter,
context);
/* And build the replacement WindowFunc node */
newexpr = makeNode(WindowFunc);
newexpr->winfnoid = expr->winfnoid;
newexpr->wintype = expr->wintype;
newexpr->wincollid = expr->wincollid;
newexpr->inputcollid = expr->inputcollid;
newexpr->args = args;
newexpr->aggfilter = aggfilter;
newexpr->winref = expr->winref;
newexpr->winstar = expr->winstar;
newexpr->winagg = expr->winagg;
newexpr->location = expr->location;
return (Node *) newexpr;
}
case T_FuncExpr:
{
FuncExpr *expr = (FuncExpr *) node;
List *args = expr->args;
Expr *simple;
FuncExpr *newexpr;
/*
* Code for op/func reduction is pretty bulky, so split it out
* as a separate function. Note: exprTypmod normally returns
* -1 for a FuncExpr, but not when the node is recognizably a
* length coercion; we want to preserve the typmod in the
* eventual Const if so.
*/
simple = simplify_function(expr->funcid,
expr->funcresulttype,
exprTypmod(node),
expr->funccollid,
expr->inputcollid,
&args,
expr->funcvariadic,
true,
true,
context);
if (simple) /* successfully simplified it */
return (Node *) simple;
/*
* The expression cannot be simplified any further, so build
* and return a replacement FuncExpr node using the
* possibly-simplified arguments. Note that we have also
* converted the argument list to positional notation.
*/
newexpr = makeNode(FuncExpr);
newexpr->funcid = expr->funcid;
newexpr->funcresulttype = expr->funcresulttype;
newexpr->funcretset = expr->funcretset;
newexpr->funcvariadic = expr->funcvariadic;
newexpr->funcformat = expr->funcformat;
newexpr->funccollid = expr->funccollid;
newexpr->inputcollid = expr->inputcollid;
newexpr->args = args;
newexpr->location = expr->location;
return (Node *) newexpr;
}
case T_OpExpr:
{
OpExpr *expr = (OpExpr *) node;
List *args = expr->args;
Expr *simple;
OpExpr *newexpr;
/*
* Need to get OID of underlying function. Okay to scribble
* on input to this extent.
*/
set_opfuncid(expr);
/*
* Code for op/func reduction is pretty bulky, so split it out
* as a separate function.
*/
simple = simplify_function(expr->opfuncid,
expr->opresulttype, -1,
expr->opcollid,
expr->inputcollid,
&args,
false,
true,
true,
context);
if (simple) /* successfully simplified it */
return (Node *) simple;
/*
* If the operator is boolean equality or inequality, we know
* how to simplify cases involving one constant and one
* non-constant argument.
*/
if (expr->opno == BooleanEqualOperator ||
expr->opno == BooleanNotEqualOperator)
{
simple = (Expr *) simplify_boolean_equality(expr->opno,
args);
if (simple) /* successfully simplified it */
return (Node *) simple;
}
/*
* The expression cannot be simplified any further, so build
* and return a replacement OpExpr node using the
* possibly-simplified arguments.
*/
newexpr = makeNode(OpExpr);
newexpr->opno = expr->opno;
newexpr->opfuncid = expr->opfuncid;
newexpr->opresulttype = expr->opresulttype;
newexpr->opretset = expr->opretset;
newexpr->opcollid = expr->opcollid;
newexpr->inputcollid = expr->inputcollid;
newexpr->args = args;
newexpr->location = expr->location;
return (Node *) newexpr;
}
case T_DistinctExpr:
{
DistinctExpr *expr = (DistinctExpr *) node;
List *args;
ListCell *arg;
bool has_null_input = false;
bool all_null_input = true;
bool has_nonconst_input = false;
Expr *simple;
DistinctExpr *newexpr;
/*
* Reduce constants in the DistinctExpr's arguments. We know
* args is either NIL or a List node, so we can call
* expression_tree_mutator directly rather than recursing to
* self.
*/
args = (List *) expression_tree_mutator((Node *) expr->args,
eval_const_expressions_mutator,
(void *) context);
/*
* We must do our own check for NULLs because DistinctExpr has
* different results for NULL input than the underlying
* operator does.
*/
foreach(arg, args)
{
if (IsA(lfirst(arg), Const))
{
has_null_input |= ((Const *) lfirst(arg))->constisnull;
all_null_input &= ((Const *) lfirst(arg))->constisnull;
}
else
has_nonconst_input = true;
}
/* all constants? then can optimize this out */
if (!has_nonconst_input)
{
/* all nulls? then not distinct */
if (all_null_input)
return makeBoolConst(false, false);
/* one null? then distinct */
if (has_null_input)
return makeBoolConst(true, false);
/* otherwise try to evaluate the '=' operator */
/* (NOT okay to try to inline it, though!) */
/*
* Need to get OID of underlying function. Okay to
* scribble on input to this extent.
*/
set_opfuncid((OpExpr *) expr); /* rely on struct
* equivalence */
/*
* Code for op/func reduction is pretty bulky, so split it
* out as a separate function.
*/
simple = simplify_function(expr->opfuncid,
expr->opresulttype, -1,
expr->opcollid,
expr->inputcollid,
&args,
false,
false,
false,
context);
if (simple) /* successfully simplified it */
{
/*
* Since the underlying operator is "=", must negate
* its result
*/
Const *csimple = (Const *) simple;
Assert(IsA(csimple, Const));
csimple->constvalue =
BoolGetDatum(!DatumGetBool(csimple->constvalue));
return (Node *) csimple;
}
}
/*
* The expression cannot be simplified any further, so build
* and return a replacement DistinctExpr node using the
* possibly-simplified arguments.
*/
newexpr = makeNode(DistinctExpr);
newexpr->opno = expr->opno;
newexpr->opfuncid = expr->opfuncid;
newexpr->opresulttype = expr->opresulttype;
newexpr->opretset = expr->opretset;
newexpr->opcollid = expr->opcollid;
newexpr->inputcollid = expr->inputcollid;
newexpr->args = args;
newexpr->location = expr->location;
return (Node *) newexpr;
}
case T_BoolExpr:
{
BoolExpr *expr = (BoolExpr *) node;
switch (expr->boolop)
{
case OR_EXPR:
{
List *newargs;
bool haveNull = false;
bool forceTrue = false;
newargs = simplify_or_arguments(expr->args,
context,
&haveNull,
&forceTrue);
if (forceTrue)
return makeBoolConst(true, false);
if (haveNull)
newargs = lappend(newargs,
makeBoolConst(false, true));
/* If all the inputs are FALSE, result is FALSE */
if (newargs == NIL)
return makeBoolConst(false, false);
/*
* If only one nonconst-or-NULL input, it's the
* result
*/
if (list_length(newargs) == 1)
return (Node *) linitial(newargs);
/* Else we still need an OR node */
return (Node *) make_orclause(newargs);
}
case AND_EXPR:
{
List *newargs;
bool haveNull = false;
bool forceFalse = false;
newargs = simplify_and_arguments(expr->args,
context,
&haveNull,
&forceFalse);
if (forceFalse)
return makeBoolConst(false, false);
if (haveNull)
newargs = lappend(newargs,
makeBoolConst(false, true));
/* If all the inputs are TRUE, result is TRUE */
if (newargs == NIL)
return makeBoolConst(true, false);
/*
* If only one nonconst-or-NULL input, it's the
* result
*/
if (list_length(newargs) == 1)
return (Node *) linitial(newargs);
/* Else we still need an AND node */
return (Node *) make_andclause(newargs);
}
case NOT_EXPR:
{
Node *arg;
Assert(list_length(expr->args) == 1);
arg = eval_const_expressions_mutator(linitial(expr->args),
context);
/*
* Use negate_clause() to see if we can simplify
* away the NOT.
*/
return negate_clause(arg);
}
default:
elog(ERROR, "unrecognized boolop: %d",
(int) expr->boolop);
break;
}
break;
}
case T_SubPlan:
case T_AlternativeSubPlan:
/*
* Return a SubPlan unchanged --- too late to do anything with it.
*
* XXX should we ereport() here instead? Probably this routine
* should never be invoked after SubPlan creation.
*/
return node;
case T_RelabelType:
{
/*
* If we can simplify the input to a constant, then we don't
* need the RelabelType node anymore: just change the type
* field of the Const node. Otherwise, must copy the
* RelabelType node.
*/
RelabelType *relabel = (RelabelType *) node;
Node *arg;
arg = eval_const_expressions_mutator((Node *) relabel->arg,
context);
/*
* If we find stacked RelabelTypes (eg, from foo :: int ::
* oid) we can discard all but the top one.
*/
while (arg && IsA(arg, RelabelType))
arg = (Node *) ((RelabelType *) arg)->arg;
if (arg && IsA(arg, Const))
{
Const *con = (Const *) arg;
con->consttype = relabel->resulttype;
con->consttypmod = relabel->resulttypmod;
con->constcollid = relabel->resultcollid;
return (Node *) con;
}
else
{
RelabelType *newrelabel = makeNode(RelabelType);
newrelabel->arg = (Expr *) arg;
newrelabel->resulttype = relabel->resulttype;
newrelabel->resulttypmod = relabel->resulttypmod;
newrelabel->resultcollid = relabel->resultcollid;
newrelabel->relabelformat = relabel->relabelformat;
newrelabel->location = relabel->location;
return (Node *) newrelabel;
}
}
case T_CoerceViaIO:
{
CoerceViaIO *expr = (CoerceViaIO *) node;
List *args;
Oid outfunc;
bool outtypisvarlena;
Oid infunc;
Oid intypioparam;
Expr *simple;
CoerceViaIO *newexpr;
/* Make a List so we can use simplify_function */
args = list_make1(expr->arg);
/*
* CoerceViaIO represents calling the source type's output
* function then the result type's input function. So, try to
* simplify it as though it were a stack of two such function
* calls. First we need to know what the functions are.
*
* Note that the coercion functions are assumed not to care
* about input collation, so we just pass InvalidOid for that.
*/
getTypeOutputInfo(exprType((Node *) expr->arg),
&outfunc, &outtypisvarlena);
getTypeInputInfo(expr->resulttype,
&infunc, &intypioparam);
simple = simplify_function(outfunc,
CSTRINGOID, -1,
InvalidOid,
InvalidOid,
&args,
false,
true,
true,
context);
if (simple) /* successfully simplified output fn */
{
/*
* Input functions may want 1 to 3 arguments. We always
* supply all three, trusting that nothing downstream will
* complain.
*/
args = list_make3(simple,
makeConst(OIDOID,
-1,
InvalidOid,
sizeof(Oid),
ObjectIdGetDatum(intypioparam),
false,
true),
makeConst(INT4OID,
-1,
InvalidOid,
sizeof(int32),
Int32GetDatum(-1),
false,
true));
simple = simplify_function(infunc,
expr->resulttype, -1,
expr->resultcollid,
InvalidOid,
&args,
false,
false,
true,
context);
if (simple) /* successfully simplified input fn */
return (Node *) simple;
}
/*
* The expression cannot be simplified any further, so build
* and return a replacement CoerceViaIO node using the
* possibly-simplified argument.
*/
newexpr = makeNode(CoerceViaIO);
newexpr->arg = (Expr *) linitial(args);
newexpr->resulttype = expr->resulttype;
newexpr->resultcollid = expr->resultcollid;
newexpr->coerceformat = expr->coerceformat;
newexpr->location = expr->location;
return (Node *) newexpr;
}
case T_ArrayCoerceExpr:
{
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
Expr *arg;
ArrayCoerceExpr *newexpr;
/*
* Reduce constants in the ArrayCoerceExpr's argument, then
* build a new ArrayCoerceExpr.
*/
arg = (Expr *) eval_const_expressions_mutator((Node *) expr->arg,
context);
newexpr = makeNode(ArrayCoerceExpr);
newexpr->arg = arg;
newexpr->elemfuncid = expr->elemfuncid;
newexpr->resulttype = expr->resulttype;
newexpr->resulttypmod = expr->resulttypmod;
newexpr->resultcollid = expr->resultcollid;
newexpr->isExplicit = expr->isExplicit;
newexpr->coerceformat = expr->coerceformat;
newexpr->location = expr->location;
/*
* If constant argument and it's a binary-coercible or
* immutable conversion, we can simplify it to a constant.
*/
if (arg && IsA(arg, Const) &&
(!OidIsValid(newexpr->elemfuncid) ||
func_volatile(newexpr->elemfuncid) == PROVOLATILE_IMMUTABLE))
return (Node *) evaluate_expr((Expr *) newexpr,
newexpr->resulttype,
newexpr->resulttypmod,
newexpr->resultcollid);
/* Else we must return the partially-simplified node */
return (Node *) newexpr;
}
case T_CollateExpr:
{
/*
* If we can simplify the input to a constant, then we don't
* need the CollateExpr node at all: just change the
* constcollid field of the Const node. Otherwise, replace
* the CollateExpr with a RelabelType. (We do that so as to
* improve uniformity of expression representation and thus
* simplify comparison of expressions.)
*/
CollateExpr *collate = (CollateExpr *) node;
Node *arg;
arg = eval_const_expressions_mutator((Node *) collate->arg,
context);
if (arg && IsA(arg, Const))
{
Const *con = (Const *) arg;
con->constcollid = collate->collOid;
return (Node *) con;
}
else if (collate->collOid == exprCollation(arg))
{
/* Don't need a RelabelType either... */
return arg;
}
else
{
RelabelType *relabel = makeNode(RelabelType);
relabel->resulttype = exprType(arg);
relabel->resulttypmod = exprTypmod(arg);
relabel->resultcollid = collate->collOid;
relabel->relabelformat = COERCE_IMPLICIT_CAST;
relabel->location = collate->location;
/* Don't create stacked RelabelTypes */
while (arg && IsA(arg, RelabelType))
arg = (Node *) ((RelabelType *) arg)->arg;
relabel->arg = (Expr *) arg;
return (Node *) relabel;
}
}
case T_CaseExpr:
{
/*----------
* CASE expressions can be simplified if there are constant
* condition clauses:
* FALSE (or NULL): drop the alternative
* TRUE: drop all remaining alternatives
* If the first non-FALSE alternative is a constant TRUE,
* we can simplify the entire CASE to that alternative's
* expression. If there are no non-FALSE alternatives,
* we simplify the entire CASE to the default result (ELSE).
*
* If we have a simple-form CASE with constant test
* expression, we substitute the constant value for contained
* CaseTestExpr placeholder nodes, so that we have the
* opportunity to reduce constant test conditions. For
* example this allows
* CASE 0 WHEN 0 THEN 1 ELSE 1/0 END
* to reduce to 1 rather than drawing a divide-by-0 error.
* Note that when the test expression is constant, we don't
* have to include it in the resulting CASE; for example
* CASE 0 WHEN x THEN y ELSE z END
* is transformed by the parser to
* CASE 0 WHEN CaseTestExpr = x THEN y ELSE z END
* which we can simplify to
* CASE WHEN 0 = x THEN y ELSE z END
* It is not necessary for the executor to evaluate the "arg"
* expression when executing the CASE, since any contained
* CaseTestExprs that might have referred to it will have been
* replaced by the constant.
*----------
*/
CaseExpr *caseexpr = (CaseExpr *) node;
CaseExpr *newcase;
Node *save_case_val;
Node *newarg;
List *newargs;
bool const_true_cond;
Node *defresult = NULL;
ListCell *arg;
/* Simplify the test expression, if any */
newarg = eval_const_expressions_mutator((Node *) caseexpr->arg,
context);
/* Set up for contained CaseTestExpr nodes */
save_case_val = context->case_val;
if (newarg && IsA(newarg, Const))
{
context->case_val = newarg;
newarg = NULL; /* not needed anymore, see above */
}
else
context->case_val = NULL;
/* Simplify the WHEN clauses */
newargs = NIL;
const_true_cond = false;
foreach(arg, caseexpr->args)
{
CaseWhen *oldcasewhen = (CaseWhen *) lfirst(arg);
Node *casecond;
Node *caseresult;
Assert(IsA(oldcasewhen, CaseWhen));
/* Simplify this alternative's test condition */
casecond = eval_const_expressions_mutator((Node *) oldcasewhen->expr,
context);
/*
* If the test condition is constant FALSE (or NULL), then
* drop this WHEN clause completely, without processing
* the result.
*/
if (casecond && IsA(casecond, Const))
{
Const *const_input = (Const *) casecond;
if (const_input->constisnull ||
!DatumGetBool(const_input->constvalue))
continue; /* drop alternative with FALSE cond */
/* Else it's constant TRUE */
const_true_cond = true;
}
/* Simplify this alternative's result value */
caseresult = eval_const_expressions_mutator((Node *) oldcasewhen->result,
context);
/* If non-constant test condition, emit a new WHEN node */
if (!const_true_cond)
{
CaseWhen *newcasewhen = makeNode(CaseWhen);
newcasewhen->expr = (Expr *) casecond;
newcasewhen->result = (Expr *) caseresult;
newcasewhen->location = oldcasewhen->location;
newargs = lappend(newargs, newcasewhen);
continue;
}
/*
* Found a TRUE condition, so none of the remaining
* alternatives can be reached. We treat the result as
* the default result.
*/
defresult = caseresult;
break;
}
/* Simplify the default result, unless we replaced it above */
if (!const_true_cond)
defresult = eval_const_expressions_mutator((Node *) caseexpr->defresult,
context);
context->case_val = save_case_val;
/*
* If no non-FALSE alternatives, CASE reduces to the default
* result
*/
if (newargs == NIL)
return defresult;
/* Otherwise we need a new CASE node */
newcase = makeNode(CaseExpr);
newcase->casetype = caseexpr->casetype;
newcase->casecollid = caseexpr->casecollid;
newcase->arg = (Expr *) newarg;
newcase->args = newargs;
newcase->defresult = (Expr *) defresult;
newcase->location = caseexpr->location;
return (Node *) newcase;
}
case T_CaseTestExpr:
{
/*
* If we know a constant test value for the current CASE
* construct, substitute it for the placeholder. Else just
* return the placeholder as-is.
*/
if (context->case_val)
return copyObject(context->case_val);
else
return copyObject(node);
}
case T_ArrayExpr:
{
ArrayExpr *arrayexpr = (ArrayExpr *) node;
ArrayExpr *newarray;
bool all_const = true;
List *newelems;
ListCell *element;
newelems = NIL;
foreach(element, arrayexpr->elements)
{
Node *e;
e = eval_const_expressions_mutator((Node *) lfirst(element),
context);
if (!IsA(e, Const))
all_const = false;
newelems = lappend(newelems, e);
}
newarray = makeNode(ArrayExpr);
newarray->array_typeid = arrayexpr->array_typeid;
newarray->array_collid = arrayexpr->array_collid;
newarray->element_typeid = arrayexpr->element_typeid;
newarray->elements = newelems;
newarray->multidims = arrayexpr->multidims;
newarray->location = arrayexpr->location;
if (all_const)
return (Node *) evaluate_expr((Expr *) newarray,
newarray->array_typeid,
exprTypmod(node),
newarray->array_collid);
return (Node *) newarray;
}
case T_CoalesceExpr:
{
CoalesceExpr *coalesceexpr = (CoalesceExpr *) node;
CoalesceExpr *newcoalesce;
List *newargs;
ListCell *arg;
newargs = NIL;
foreach(arg, coalesceexpr->args)
{
Node *e;
e = eval_const_expressions_mutator((Node *) lfirst(arg),
context);
/*
* We can remove null constants from the list. For a
* non-null constant, if it has not been preceded by any
* other non-null-constant expressions then it is the
* result. Otherwise, it's the next argument, but we can
* drop following arguments since they will never be
* reached.
*/
if (IsA(e, Const))
{
if (((Const *) e)->constisnull)
continue; /* drop null constant */
if (newargs == NIL)
return e; /* first expr */
newargs = lappend(newargs, e);
break;
}
newargs = lappend(newargs, e);
}
/*
* If all the arguments were constant null, the result is just
* null
*/
if (newargs == NIL)
return (Node *) makeNullConst(coalesceexpr->coalescetype,
-1,
coalesceexpr->coalescecollid);
newcoalesce = makeNode(CoalesceExpr);
newcoalesce->coalescetype = coalesceexpr->coalescetype;
newcoalesce->coalescecollid = coalesceexpr->coalescecollid;
newcoalesce->args = newargs;
newcoalesce->location = coalesceexpr->location;
return (Node *) newcoalesce;
}
case T_FieldSelect:
{
/*
* We can optimize field selection from a whole-row Var into a
* simple Var. (This case won't be generated directly by the
* parser, because ParseComplexProjection short-circuits it.
* But it can arise while simplifying functions.) Also, we
* can optimize field selection from a RowExpr construct.
*
* However, replacing a whole-row Var in this way has a
* pitfall: if we've already built the reltargetlist for the
* source relation, then the whole-row Var is scheduled to be
* produced by the relation scan, but the simple Var probably
* isn't, which will lead to a failure in setrefs.c. This is
* not a problem when handling simple single-level queries, in
* which expression simplification always happens first. It
* is a risk for lateral references from subqueries, though.
* To avoid such failures, don't optimize uplevel references.
*
* We must also check that the declared type of the field is
* still the same as when the FieldSelect was created --- this
* can change if someone did ALTER COLUMN TYPE on the rowtype.
*/
FieldSelect *fselect = (FieldSelect *) node;
FieldSelect *newfselect;
Node *arg;
arg = eval_const_expressions_mutator((Node *) fselect->arg,
context);
if (arg && IsA(arg, Var) &&
((Var *) arg)->varattno == InvalidAttrNumber &&
((Var *) arg)->varlevelsup == 0)
{
if (rowtype_field_matches(((Var *) arg)->vartype,
fselect->fieldnum,
fselect->resulttype,
fselect->resulttypmod,
fselect->resultcollid))
return (Node *) makeVar(((Var *) arg)->varno,
fselect->fieldnum,
fselect->resulttype,
fselect->resulttypmod,
fselect->resultcollid,
((Var *) arg)->varlevelsup);
}
if (arg && IsA(arg, RowExpr))
{
RowExpr *rowexpr = (RowExpr *) arg;
if (fselect->fieldnum > 0 &&
fselect->fieldnum <= list_length(rowexpr->args))
{
Node *fld = (Node *) list_nth(rowexpr->args,
fselect->fieldnum - 1);
if (rowtype_field_matches(rowexpr->row_typeid,
fselect->fieldnum,
fselect->resulttype,
fselect->resulttypmod,
fselect->resultcollid) &&
fselect->resulttype == exprType(fld) &&
fselect->resulttypmod == exprTypmod(fld) &&
fselect->resultcollid == exprCollation(fld))
return fld;
}
}
newfselect = makeNode(FieldSelect);
newfselect->arg = (Expr *) arg;
newfselect->fieldnum = fselect->fieldnum;
newfselect->resulttype = fselect->resulttype;
newfselect->resulttypmod = fselect->resulttypmod;
newfselect->resultcollid = fselect->resultcollid;
return (Node *) newfselect;
}
case T_NullTest:
{
NullTest *ntest = (NullTest *) node;
NullTest *newntest;
Node *arg;
arg = eval_const_expressions_mutator((Node *) ntest->arg,
context);
if (ntest->argisrow && arg && IsA(arg, RowExpr))
{
/*
* We break ROW(...) IS [NOT] NULL into separate tests on
* its component fields. This form is usually more
* efficient to evaluate, as well as being more amenable
* to optimization.
*/
RowExpr *rarg = (RowExpr *) arg;
List *newargs = NIL;
ListCell *l;
foreach(l, rarg->args)
{
Node *relem = (Node *) lfirst(l);
/*
* A constant field refutes the whole NullTest if it's
* of the wrong nullness; else we can discard it.
*/
if (relem && IsA(relem, Const))
{
Const *carg = (Const *) relem;
if (carg->constisnull ?
(ntest->nulltesttype == IS_NOT_NULL) :
(ntest->nulltesttype == IS_NULL))
return makeBoolConst(false, false);
continue;
}
/*
* Else, make a scalar (argisrow == false) NullTest
* for this field. Scalar semantics are required
* because IS [NOT] NULL doesn't recurse; see comments
* in ExecEvalNullTest().
*/
newntest = makeNode(NullTest);
newntest->arg = (Expr *) relem;
newntest->nulltesttype = ntest->nulltesttype;
newntest->argisrow = false;
newntest->location = ntest->location;
newargs = lappend(newargs, newntest);
}
/* If all the inputs were constants, result is TRUE */
if (newargs == NIL)
return makeBoolConst(true, false);
/* If only one nonconst input, it's the result */
if (list_length(newargs) == 1)
return (Node *) linitial(newargs);
/* Else we need an AND node */
return (Node *) make_andclause(newargs);
}
if (!ntest->argisrow && arg && IsA(arg, Const))
{
Const *carg = (Const *) arg;
bool result;
switch (ntest->nulltesttype)
{
case IS_NULL:
result = carg->constisnull;
break;
case IS_NOT_NULL:
result = !carg->constisnull;
break;
default:
elog(ERROR, "unrecognized nulltesttype: %d",
(int) ntest->nulltesttype);
result = false; /* keep compiler quiet */
break;
}
return makeBoolConst(result, false);
}
newntest = makeNode(NullTest);
newntest->arg = (Expr *) arg;
newntest->nulltesttype = ntest->nulltesttype;
newntest->argisrow = ntest->argisrow;
newntest->location = ntest->location;
return (Node *) newntest;
}
case T_BooleanTest:
{
BooleanTest *btest = (BooleanTest *) node;
BooleanTest *newbtest;
Node *arg;
arg = eval_const_expressions_mutator((Node *) btest->arg,
context);
if (arg && IsA(arg, Const))
{
Const *carg = (Const *) arg;
bool result;
switch (btest->booltesttype)
{
case IS_TRUE:
result = (!carg->constisnull &&
DatumGetBool(carg->constvalue));
break;
case IS_NOT_TRUE:
result = (carg->constisnull ||
!DatumGetBool(carg->constvalue));
break;
case IS_FALSE:
result = (!carg->constisnull &&
!DatumGetBool(carg->constvalue));
break;
case IS_NOT_FALSE:
result = (carg->constisnull ||
DatumGetBool(carg->constvalue));
break;
case IS_UNKNOWN:
result = carg->constisnull;
break;
case IS_NOT_UNKNOWN:
result = !carg->constisnull;
break;
default:
elog(ERROR, "unrecognized booltesttype: %d",
(int) btest->booltesttype);
result = false; /* keep compiler quiet */
break;
}
return makeBoolConst(result, false);
}
newbtest = makeNode(BooleanTest);
newbtest->arg = (Expr *) arg;
newbtest->booltesttype = btest->booltesttype;
newbtest->location = btest->location;
return (Node *) newbtest;
}
case T_PlaceHolderVar:
/*
* In estimation mode, just strip the PlaceHolderVar node
* altogether; this amounts to estimating that the contained value
* won't be forced to null by an outer join. In regular mode we
* just use the default behavior (ie, simplify the expression but
* leave the PlaceHolderVar node intact).
*/
if (context->estimate)
{
PlaceHolderVar *phv = (PlaceHolderVar *) node;
return eval_const_expressions_mutator((Node *) phv->phexpr,
context);
}
break;
default:
break;
}
/*
* For any node type not handled above, we recurse using
* expression_tree_mutator, which will copy the node unchanged but try to
* simplify its arguments (if any) using this routine. For example: we
* cannot eliminate an ArrayRef node, but we might be able to simplify
* constant expressions in its subscripts.
*/
return expression_tree_mutator(node, eval_const_expressions_mutator,
(void *) context);
}
/*
* Subroutine for eval_const_expressions: process arguments of an OR clause
*
* This includes flattening of nested ORs as well as recursion to
* eval_const_expressions to simplify the OR arguments.
*
* After simplification, OR arguments are handled as follows:
* non constant: keep
* FALSE: drop (does not affect result)
* TRUE: force result to TRUE
* NULL: keep only one
* We must keep one NULL input because ExecEvalOr returns NULL when no input
* is TRUE and at least one is NULL. We don't actually include the NULL
* here, that's supposed to be done by the caller.
*
* The output arguments *haveNull and *forceTrue must be initialized FALSE
* by the caller. They will be set TRUE if a null constant or true constant,
* respectively, is detected anywhere in the argument list.
*/
static List *
simplify_or_arguments(List *args,
eval_const_expressions_context *context,
bool *haveNull, bool *forceTrue)
{
List *newargs = NIL;
List *unprocessed_args;
/*
* We want to ensure that any OR immediately beneath another OR gets
* flattened into a single OR-list, so as to simplify later reasoning.
*
* To avoid stack overflow from recursion of eval_const_expressions, we
* resort to some tenseness here: we keep a list of not-yet-processed
* inputs, and handle flattening of nested ORs by prepending to the to-do
* list instead of recursing. Now that the parser generates N-argument
* ORs from simple lists, this complexity is probably less necessary than
* it once was, but we might as well keep the logic.
*/
unprocessed_args = list_copy(args);
while (unprocessed_args)
{
Node *arg = (Node *) linitial(unprocessed_args);
unprocessed_args = list_delete_first(unprocessed_args);
/* flatten nested ORs as per above comment */
if (or_clause(arg))
{
List *subargs = list_copy(((BoolExpr *) arg)->args);
/* overly tense code to avoid leaking unused list header */
if (!unprocessed_args)
unprocessed_args = subargs;
else
{
List *oldhdr = unprocessed_args;
unprocessed_args = list_concat(subargs, unprocessed_args);
pfree(oldhdr);
}
continue;
}
/* If it's not an OR, simplify it */
arg = eval_const_expressions_mutator(arg, context);
/*
* It is unlikely but not impossible for simplification of a non-OR
* clause to produce an OR. Recheck, but don't be too tense about it
* since it's not a mainstream case. In particular we don't worry
* about const-simplifying the input twice.
*/
if (or_clause(arg))
{
List *subargs = list_copy(((BoolExpr *) arg)->args);
unprocessed_args = list_concat(subargs, unprocessed_args);
continue;
}
/*
* OK, we have a const-simplified non-OR argument. Process it per
* comments above.
*/
if (IsA(arg, Const))
{
Const *const_input = (Const *) arg;
if (const_input->constisnull)
*haveNull = true;
else if (DatumGetBool(const_input->constvalue))
{
*forceTrue = true;
/*
* Once we detect a TRUE result we can just exit the loop
* immediately. However, if we ever add a notion of
* non-removable functions, we'd need to keep scanning.
*/
return NIL;
}
/* otherwise, we can drop the constant-false input */
continue;
}
/* else emit the simplified arg into the result list */
newargs = lappend(newargs, arg);
}
return newargs;
}
/*
* Subroutine for eval_const_expressions: process arguments of an AND clause
*
* This includes flattening of nested ANDs as well as recursion to
* eval_const_expressions to simplify the AND arguments.
*
* After simplification, AND arguments are handled as follows:
* non constant: keep
* TRUE: drop (does not affect result)
* FALSE: force result to FALSE
* NULL: keep only one
* We must keep one NULL input because ExecEvalAnd returns NULL when no input
* is FALSE and at least one is NULL. We don't actually include the NULL
* here, that's supposed to be done by the caller.
*
* The output arguments *haveNull and *forceFalse must be initialized FALSE
* by the caller. They will be set TRUE if a null constant or false constant,
* respectively, is detected anywhere in the argument list.
*/
static List *
simplify_and_arguments(List *args,
eval_const_expressions_context *context,
bool *haveNull, bool *forceFalse)
{
List *newargs = NIL;
List *unprocessed_args;
/* See comments in simplify_or_arguments */
unprocessed_args = list_copy(args);
while (unprocessed_args)
{
Node *arg = (Node *) linitial(unprocessed_args);
unprocessed_args = list_delete_first(unprocessed_args);
/* flatten nested ANDs as per above comment */
if (and_clause(arg))
{
List *subargs = list_copy(((BoolExpr *) arg)->args);
/* overly tense code to avoid leaking unused list header */
if (!unprocessed_args)
unprocessed_args = subargs;
else
{
List *oldhdr = unprocessed_args;
unprocessed_args = list_concat(subargs, unprocessed_args);
pfree(oldhdr);
}
continue;
}
/* If it's not an AND, simplify it */
arg = eval_const_expressions_mutator(arg, context);
/*
* It is unlikely but not impossible for simplification of a non-AND
* clause to produce an AND. Recheck, but don't be too tense about it
* since it's not a mainstream case. In particular we don't worry
* about const-simplifying the input twice.
*/
if (and_clause(arg))
{
List *subargs = list_copy(((BoolExpr *) arg)->args);
unprocessed_args = list_concat(subargs, unprocessed_args);
continue;
}
/*
* OK, we have a const-simplified non-AND argument. Process it per
* comments above.
*/
if (IsA(arg, Const))
{
Const *const_input = (Const *) arg;
if (const_input->constisnull)
*haveNull = true;
else if (!DatumGetBool(const_input->constvalue))
{
*forceFalse = true;
/*
* Once we detect a FALSE result we can just exit the loop
* immediately. However, if we ever add a notion of
* non-removable functions, we'd need to keep scanning.
*/
return NIL;
}
/* otherwise, we can drop the constant-true input */
continue;
}
/* else emit the simplified arg into the result list */
newargs = lappend(newargs, arg);
}
return newargs;
}
/*
* Subroutine for eval_const_expressions: try to simplify boolean equality
* or inequality condition
*
* Inputs are the operator OID and the simplified arguments to the operator.
* Returns a simplified expression if successful, or NULL if cannot
* simplify the expression.
*
* The idea here is to reduce "x = true" to "x" and "x = false" to "NOT x",
* or similarly "x <> true" to "NOT x" and "x <> false" to "x".
* This is only marginally useful in itself, but doing it in constant folding
* ensures that we will recognize these forms as being equivalent in, for
* example, partial index matching.
*
* We come here only if simplify_function has failed; therefore we cannot
* see two constant inputs, nor a constant-NULL input.
*/
static Node *
simplify_boolean_equality(Oid opno, List *args)
{
Node *leftop;
Node *rightop;
Assert(list_length(args) == 2);
leftop = linitial(args);
rightop = lsecond(args);
if (leftop && IsA(leftop, Const))
{
Assert(!((Const *) leftop)->constisnull);
if (opno == BooleanEqualOperator)
{
if (DatumGetBool(((Const *) leftop)->constvalue))
return rightop; /* true = foo */
else
return negate_clause(rightop); /* false = foo */
}
else
{
if (DatumGetBool(((Const *) leftop)->constvalue))
return negate_clause(rightop); /* true <> foo */
else
return rightop; /* false <> foo */
}
}
if (rightop && IsA(rightop, Const))
{
Assert(!((Const *) rightop)->constisnull);
if (opno == BooleanEqualOperator)
{
if (DatumGetBool(((Const *) rightop)->constvalue))
return leftop; /* foo = true */
else
return negate_clause(leftop); /* foo = false */
}
else
{
if (DatumGetBool(((Const *) rightop)->constvalue))
return negate_clause(leftop); /* foo <> true */
else
return leftop; /* foo <> false */
}
}
return NULL;
}
/*
* Subroutine for eval_const_expressions: try to simplify a function call
* (which might originally have been an operator; we don't care)
*
* Inputs are the function OID, actual result type OID (which is needed for
* polymorphic functions), result typmod, result collation, the input
* collation to use for the function, the original argument list (not
* const-simplified yet, unless process_args is false), and some flags;
* also the context data for eval_const_expressions.
*
* Returns a simplified expression if successful, or NULL if cannot
* simplify the function call.
*
* This function is also responsible for converting named-notation argument
* lists into positional notation and/or adding any needed default argument
* expressions; which is a bit grotty, but it avoids extra fetches of the
* function's pg_proc tuple. For this reason, the args list is
* pass-by-reference. Conversion and const-simplification of the args list
* will be done even if simplification of the function call itself is not
* possible.
*/
static Expr *
simplify_function(Oid funcid, Oid result_type, int32 result_typmod,
Oid result_collid, Oid input_collid, List **args_p,
bool funcvariadic, bool process_args, bool allow_non_const,
eval_const_expressions_context *context)
{
List *args = *args_p;
HeapTuple func_tuple;
Form_pg_proc func_form;
Expr *newexpr;
/*
* We have three strategies for simplification: execute the function to
* deliver a constant result, use a transform function to generate a
* substitute node tree, or expand in-line the body of the function
* definition (which only works for simple SQL-language functions, but
* that is a common case). Each case needs access to the function's
* pg_proc tuple, so fetch it just once.
*
* Note: the allow_non_const flag suppresses both the second and third
* strategies; so if !allow_non_const, simplify_function can only return a
* Const or NULL. Argument-list rewriting happens anyway, though.
*/
func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
if (!HeapTupleIsValid(func_tuple))
elog(ERROR, "cache lookup failed for function %u", funcid);
func_form = (Form_pg_proc) GETSTRUCT(func_tuple);
/*
* Process the function arguments, unless the caller did it already.
*
* Here we must deal with named or defaulted arguments, and then
* recursively apply eval_const_expressions to the whole argument list.
*/
if (process_args)
{
args = expand_function_arguments(args, result_type, func_tuple);
args = (List *) expression_tree_mutator((Node *) args,
eval_const_expressions_mutator,
(void *) context);
/* Argument processing done, give it back to the caller */
*args_p = args;
}
/* Now attempt simplification of the function call proper. */
newexpr = evaluate_function(funcid, result_type, result_typmod,
result_collid, input_collid,
args, funcvariadic,
func_tuple, context);
if (!newexpr && allow_non_const && OidIsValid(func_form->protransform))
{
/*
* Build a dummy FuncExpr node containing the simplified arg list. We
* use this approach to present a uniform interface to the transform
* function regardless of how the function is actually being invoked.
*/
FuncExpr fexpr;
fexpr.xpr.type = T_FuncExpr;
fexpr.funcid = funcid;
fexpr.funcresulttype = result_type;
fexpr.funcretset = func_form->proretset;
fexpr.funcvariadic = funcvariadic;
fexpr.funcformat = COERCE_EXPLICIT_CALL;
fexpr.funccollid = result_collid;
fexpr.inputcollid = input_collid;
fexpr.args = args;
fexpr.location = -1;
newexpr = (Expr *)
DatumGetPointer(OidFunctionCall1(func_form->protransform,
PointerGetDatum(&fexpr)));
}
if (!newexpr && allow_non_const)
newexpr = inline_function(funcid, result_type, result_collid,
input_collid, args, funcvariadic,
func_tuple, context);
ReleaseSysCache(func_tuple);
return newexpr;
}
/*
* expand_function_arguments: convert named-notation args to positional args
* and/or insert default args, as needed
*
* If we need to change anything, the input argument list is copied, not
* modified.
*
* Note: this gets applied to operator argument lists too, even though the
* cases it handles should never occur there. This should be OK since it
* will fall through very quickly if there's nothing to do.
*/
static List *
expand_function_arguments(List *args, Oid result_type, HeapTuple func_tuple)
{
Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
bool has_named_args = false;
ListCell *lc;
/* Do we have any named arguments? */
foreach(lc, args)
{
Node *arg = (Node *) lfirst(lc);
if (IsA(arg, NamedArgExpr))
{
has_named_args = true;
break;
}
}
/* If so, we must apply reorder_function_arguments */
if (has_named_args)
{
args = reorder_function_arguments(args, func_tuple);
/* Recheck argument types and add casts if needed */
recheck_cast_function_args(args, result_type, func_tuple);
}
else if (list_length(args) < funcform->pronargs)
{
/* No named args, but we seem to be short some defaults */
args = add_function_defaults(args, func_tuple);
/* Recheck argument types and add casts if needed */
recheck_cast_function_args(args, result_type, func_tuple);
}
return args;
}
/*
* reorder_function_arguments: convert named-notation args to positional args
*
* This function also inserts default argument values as needed, since it's
* impossible to form a truly valid positional call without that.
*/
static List *
reorder_function_arguments(List *args, HeapTuple func_tuple)
{
Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
int pronargs = funcform->pronargs;
int nargsprovided = list_length(args);
Node *argarray[FUNC_MAX_ARGS];
ListCell *lc;
int i;
Assert(nargsprovided <= pronargs);
if (pronargs > FUNC_MAX_ARGS)
elog(ERROR, "too many function arguments");
MemSet(argarray, 0, pronargs * sizeof(Node *));
/* Deconstruct the argument list into an array indexed by argnumber */
i = 0;
foreach(lc, args)
{
Node *arg = (Node *) lfirst(lc);
if (!IsA(arg, NamedArgExpr))
{
/* positional argument, assumed to precede all named args */
Assert(argarray[i] == NULL);
argarray[i++] = arg;
}
else
{
NamedArgExpr *na = (NamedArgExpr *) arg;
Assert(argarray[na->argnumber] == NULL);
argarray[na->argnumber] = (Node *) na->arg;
}
}
/*
* Fetch default expressions, if needed, and insert into array at proper
* locations (they aren't necessarily consecutive or all used)
*/
if (nargsprovided < pronargs)
{
List *defaults = fetch_function_defaults(func_tuple);
i = pronargs - funcform->pronargdefaults;
foreach(lc, defaults)
{
if (argarray[i] == NULL)
argarray[i] = (Node *) lfirst(lc);
i++;
}
}
/* Now reconstruct the args list in proper order */
args = NIL;
for (i = 0; i < pronargs; i++)
{
Assert(argarray[i] != NULL);
args = lappend(args, argarray[i]);
}
return args;
}
/*
* add_function_defaults: add missing function arguments from its defaults
*
* This is used only when the argument list was positional to begin with,
* and so we know we just need to add defaults at the end.
*/
static List *
add_function_defaults(List *args, HeapTuple func_tuple)
{
Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
int nargsprovided = list_length(args);
List *defaults;
int ndelete;
/* Get all the default expressions from the pg_proc tuple */
defaults = fetch_function_defaults(func_tuple);
/* Delete any unused defaults from the list */
ndelete = nargsprovided + list_length(defaults) - funcform->pronargs;
if (ndelete < 0)
elog(ERROR, "not enough default arguments");
while (ndelete-- > 0)
defaults = list_delete_first(defaults);
/* And form the combined argument list, not modifying the input list */
return list_concat(list_copy(args), defaults);
}
/*
* fetch_function_defaults: get function's default arguments as expression list
*/
static List *
fetch_function_defaults(HeapTuple func_tuple)
{
List *defaults;
Datum proargdefaults;
bool isnull;
char *str;
/* The error cases here shouldn't happen, but check anyway */
proargdefaults = SysCacheGetAttr(PROCOID, func_tuple,
Anum_pg_proc_proargdefaults,
&isnull);
if (isnull)
elog(ERROR, "not enough default arguments");
str = TextDatumGetCString(proargdefaults);
defaults = (List *) stringToNode(str);
Assert(IsA(defaults, List));
pfree(str);
return defaults;
}
/*
* recheck_cast_function_args: recheck function args and typecast as needed
* after adding defaults.
*
* It is possible for some of the defaulted arguments to be polymorphic;
* therefore we can't assume that the default expressions have the correct
* data types already. We have to re-resolve polymorphics and do coercion
* just like the parser did.
*
* This should be a no-op if there are no polymorphic arguments,
* but we do it anyway to be sure.
*
* Note: if any casts are needed, the args list is modified in-place;
* caller should have already copied the list structure.
*/
static void
recheck_cast_function_args(List *args, Oid result_type, HeapTuple func_tuple)
{
Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
int nargs;
Oid actual_arg_types[FUNC_MAX_ARGS];
Oid declared_arg_types[FUNC_MAX_ARGS];
Oid rettype;
ListCell *lc;
if (list_length(args) > FUNC_MAX_ARGS)
elog(ERROR, "too many function arguments");
nargs = 0;
foreach(lc, args)
{
actual_arg_types[nargs++] = exprType((Node *) lfirst(lc));
}
Assert(nargs == funcform->pronargs);
memcpy(declared_arg_types, funcform->proargtypes.values,
funcform->pronargs * sizeof(Oid));
rettype = enforce_generic_type_consistency(actual_arg_types,
declared_arg_types,
nargs,
funcform->prorettype,
false);
/* let's just check we got the same answer as the parser did ... */
if (rettype != result_type)
elog(ERROR, "function's resolved result type changed during planning");
/* perform any necessary typecasting of arguments */
make_fn_arguments(NULL, args, actual_arg_types, declared_arg_types);
}
/*
* evaluate_function: try to pre-evaluate a function call
*
* We can do this if the function is strict and has any constant-null inputs
* (just return a null constant), or if the function is immutable and has all
* constant inputs (call it and return the result as a Const node). In
* estimation mode we are willing to pre-evaluate stable functions too.
*
* Returns a simplified expression if successful, or NULL if cannot
* simplify the function.
*/
static Expr *
evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
Oid result_collid, Oid input_collid, List *args,
bool funcvariadic,
HeapTuple func_tuple,
eval_const_expressions_context *context)
{
Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
bool has_nonconst_input = false;
bool has_null_input = false;
ListCell *arg;
FuncExpr *newexpr;
/*
* Can't simplify if it returns a set.
*/
if (funcform->proretset)
return NULL;
/*
* Can't simplify if it returns RECORD. The immediate problem is that it
* will be needing an expected tupdesc which we can't supply here.
*
* In the case where it has OUT parameters, it could get by without an
* expected tupdesc, but we still have issues: get_expr_result_type()
* doesn't know how to extract type info from a RECORD constant, and in
* the case of a NULL function result there doesn't seem to be any clean
* way to fix that. In view of the likelihood of there being still other
* gotchas, seems best to leave the function call unreduced.
*/
if (funcform->prorettype == RECORDOID)
return NULL;
/*
* Check for constant inputs and especially constant-NULL inputs.
*/
foreach(arg, args)
{
if (IsA(lfirst(arg), Const))
has_null_input |= ((Const *) lfirst(arg))->constisnull;
else
has_nonconst_input = true;
}
/*
* If the function is strict and has a constant-NULL input, it will never
* be called at all, so we can replace the call by a NULL constant, even
* if there are other inputs that aren't constant, and even if the
* function is not otherwise immutable.
*/
if (funcform->proisstrict && has_null_input)
return (Expr *) makeNullConst(result_type, result_typmod,
result_collid);
/*
* Otherwise, can simplify only if all inputs are constants. (For a
* non-strict function, constant NULL inputs are treated the same as
* constant non-NULL inputs.)
*/
if (has_nonconst_input)
return NULL;
/*
* Ordinarily we are only allowed to simplify immutable functions. But for
* purposes of estimation, we consider it okay to simplify functions that
* are merely stable; the risk that the result might change from planning
* time to execution time is worth taking in preference to not being able
* to estimate the value at all.
*/
if (funcform->provolatile == PROVOLATILE_IMMUTABLE)
/* okay */ ;
else if (context->estimate && funcform->provolatile == PROVOLATILE_STABLE)
/* okay */ ;
else
return NULL;
/*
* OK, looks like we can simplify this operator/function.
*
* Build a new FuncExpr node containing the already-simplified arguments.
*/
newexpr = makeNode(FuncExpr);
newexpr->funcid = funcid;
newexpr->funcresulttype = result_type;
newexpr->funcretset = false;
newexpr->funcvariadic = funcvariadic;
newexpr->funcformat = COERCE_EXPLICIT_CALL; /* doesn't matter */
newexpr->funccollid = result_collid; /* doesn't matter */
newexpr->inputcollid = input_collid;
newexpr->args = args;
newexpr->location = -1;
return evaluate_expr((Expr *) newexpr, result_type, result_typmod,
result_collid);
}
/*
* inline_function: try to expand a function call inline
*
* If the function is a sufficiently simple SQL-language function
* (just "SELECT expression"), then we can inline it and avoid the rather
* high per-call overhead of SQL functions. Furthermore, this can expose
* opportunities for constant-folding within the function expression.
*
* We have to beware of some special cases however. A directly or
* indirectly recursive function would cause us to recurse forever,
* so we keep track of which functions we are already expanding and
* do not re-expand them. Also, if a parameter is used more than once
* in the SQL-function body, we require it not to contain any volatile
* functions (volatiles might deliver inconsistent answers) nor to be
* unreasonably expensive to evaluate. The expensiveness check not only
* prevents us from doing multiple evaluations of an expensive parameter
* at runtime, but is a safety value to limit growth of an expression due
* to repeated inlining.
*
* We must also beware of changing the volatility or strictness status of
* functions by inlining them.
*
* Also, at the moment we can't inline functions returning RECORD. This
* doesn't work in the general case because it discards information such
* as OUT-parameter declarations.
*
* Returns a simplified expression if successful, or NULL if cannot
* simplify the function.
*/
static Expr *
inline_function(Oid funcid, Oid result_type, Oid result_collid,
Oid input_collid, List *args,
bool funcvariadic,
HeapTuple func_tuple,
eval_const_expressions_context *context)
{
Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
char *src;
Datum tmp;
bool isNull;
bool modifyTargetList;
MemoryContext oldcxt;
MemoryContext mycxt;
inline_error_callback_arg callback_arg;
ErrorContextCallback sqlerrcontext;
FuncExpr *fexpr;
SQLFunctionParseInfoPtr pinfo;
ParseState *pstate;
List *raw_parsetree_list;
Query *querytree;
Node *newexpr;
int *usecounts;
ListCell *arg;
int i;
/*
* Forget it if the function is not SQL-language or has other showstopper
* properties. (The nargs check is just paranoia.)
*/
if (funcform->prolang != SQLlanguageId ||
funcform->prosecdef ||
funcform->proretset ||
funcform->prorettype == RECORDOID ||
!heap_attisnull(func_tuple, Anum_pg_proc_proconfig) ||
funcform->pronargs != list_length(args))
return NULL;
/* Check for recursive function, and give up trying to expand if so */
if (list_member_oid(context->active_fns, funcid))
return NULL;
/* Check permission to call function (fail later, if not) */
if (pg_proc_aclcheck(funcid, GetUserId(), ACL_EXECUTE) != ACLCHECK_OK)
return NULL;
/* Check whether a plugin wants to hook function entry/exit */
if (FmgrHookIsNeeded(funcid))
return NULL;
/*
* Make a temporary memory context, so that we don't leak all the stuff
* that parsing might create.
*/
mycxt = AllocSetContextCreate(CurrentMemoryContext,
"inline_function",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
oldcxt = MemoryContextSwitchTo(mycxt);
/* Fetch the function body */
tmp = SysCacheGetAttr(PROCOID,
func_tuple,
Anum_pg_proc_prosrc,
&isNull);
if (isNull)
elog(ERROR, "null prosrc for function %u", funcid);
src = TextDatumGetCString(tmp);
/*
* Setup error traceback support for ereport(). This is so that we can
* finger the function that bad information came from.
*/
callback_arg.proname = NameStr(funcform->proname);
callback_arg.prosrc = src;
sqlerrcontext.callback = sql_inline_error_callback;
sqlerrcontext.arg = (void *) &callback_arg;
sqlerrcontext.previous = error_context_stack;
error_context_stack = &sqlerrcontext;
/*
* Set up to handle parameters while parsing the function body. We need a
* dummy FuncExpr node containing the already-simplified arguments to pass
* to prepare_sql_fn_parse_info. (It is really only needed if there are
* some polymorphic arguments, but for simplicity we always build it.)
*/
fexpr = makeNode(FuncExpr);
fexpr->funcid = funcid;
fexpr->funcresulttype = result_type;
fexpr->funcretset = false;
fexpr->funcvariadic = funcvariadic;
fexpr->funcformat = COERCE_EXPLICIT_CALL; /* doesn't matter */
fexpr->funccollid = result_collid; /* doesn't matter */
fexpr->inputcollid = input_collid;
fexpr->args = args;
fexpr->location = -1;
pinfo = prepare_sql_fn_parse_info(func_tuple,
(Node *) fexpr,
input_collid);
/*
* We just do parsing and parse analysis, not rewriting, because rewriting
* will not affect table-free-SELECT-only queries, which is all that we
* care about. Also, we can punt as soon as we detect more than one
* command in the function body.
*/
raw_parsetree_list = pg_parse_query(src);
if (list_length(raw_parsetree_list) != 1)
goto fail;
pstate = make_parsestate(NULL);
pstate->p_sourcetext = src;
sql_fn_parser_setup(pstate, pinfo);
querytree = transformTopLevelStmt(pstate, linitial(raw_parsetree_list));
free_parsestate(pstate);
/*
* The single command must be a simple "SELECT expression".
*/
if (!IsA(querytree, Query) ||
querytree->commandType != CMD_SELECT ||
querytree->utilityStmt ||
querytree->hasAggs ||
querytree->hasWindowFuncs ||
querytree->hasSubLinks ||
querytree->cteList ||
querytree->rtable ||
querytree->jointree->fromlist ||
querytree->jointree->quals ||
querytree->groupClause ||
querytree->groupingSets ||
querytree->havingQual ||
querytree->windowClause ||
querytree->distinctClause ||
querytree->sortClause ||
querytree->limitOffset ||
querytree->limitCount ||
querytree->setOperations ||
list_length(querytree->targetList) != 1)
goto fail;
/*
* Make sure the function (still) returns what it's declared to. This
* will raise an error if wrong, but that's okay since the function would
* fail at runtime anyway. Note that check_sql_fn_retval will also insert
* a RelabelType if needed to make the tlist expression match the declared
* type of the function.
*
* Note: we do not try this until we have verified that no rewriting was
* needed; that's probably not important, but let's be careful.
*/
if (check_sql_fn_retval(funcid, result_type, list_make1(querytree),
&modifyTargetList, NULL))
goto fail; /* reject whole-tuple-result cases */
/* Now we can grab the tlist expression */
newexpr = (Node *) ((TargetEntry *) linitial(querytree->targetList))->expr;
/* Assert that check_sql_fn_retval did the right thing */
Assert(exprType(newexpr) == result_type);
/* It couldn't have made any dangerous tlist changes, either */
Assert(!modifyTargetList);
/*
* Additional validity checks on the expression. It mustn't return a set,
* and it mustn't be more volatile than the surrounding function (this is
* to avoid breaking hacks that involve pretending a function is immutable
* when it really ain't). If the surrounding function is declared strict,
* then the expression must contain only strict constructs and must use
* all of the function parameters (this is overkill, but an exact analysis
* is hard).
*/
if (expression_returns_set(newexpr))
goto fail;
if (funcform->provolatile == PROVOLATILE_IMMUTABLE &&
contain_mutable_functions(newexpr))
goto fail;
else if (funcform->provolatile == PROVOLATILE_STABLE &&
contain_volatile_functions(newexpr))
goto fail;
if (funcform->proisstrict &&
contain_nonstrict_functions(newexpr))
goto fail;
/*
* We may be able to do it; there are still checks on parameter usage to
* make, but those are most easily done in combination with the actual
* substitution of the inputs. So start building expression with inputs
* substituted.
*/
usecounts = (int *) palloc0(funcform->pronargs * sizeof(int));
newexpr = substitute_actual_parameters(newexpr, funcform->pronargs,
args, usecounts);
/* Now check for parameter usage */
i = 0;
foreach(arg, args)
{
Node *param = lfirst(arg);
if (usecounts[i] == 0)
{
/* Param not used at all: uncool if func is strict */
if (funcform->proisstrict)
goto fail;
}
else if (usecounts[i] != 1)
{
/* Param used multiple times: uncool if expensive or volatile */
QualCost eval_cost;
/*
* We define "expensive" as "contains any subplan or more than 10
* operators". Note that the subplan search has to be done
* explicitly, since cost_qual_eval() will barf on unplanned
* subselects.
*/
if (contain_subplans(param))
goto fail;
cost_qual_eval(&eval_cost, list_make1(param), NULL);
if (eval_cost.startup + eval_cost.per_tuple >
10 * cpu_operator_cost)
goto fail;
/*
* Check volatility last since this is more expensive than the
* above tests
*/
if (contain_volatile_functions(param))
goto fail;
}
i++;
}
/*
* Whew --- we can make the substitution. Copy the modified expression
* out of the temporary memory context, and clean up.
*/
MemoryContextSwitchTo(oldcxt);
newexpr = copyObject(newexpr);
MemoryContextDelete(mycxt);
/*
* If the result is of a collatable type, force the result to expose the
* correct collation. In most cases this does not matter, but it's
* possible that the function result is used directly as a sort key or in
* other places where we expect exprCollation() to tell the truth.
*/
if (OidIsValid(result_collid))
{
Oid exprcoll = exprCollation(newexpr);
if (OidIsValid(exprcoll) && exprcoll != result_collid)
{
CollateExpr *newnode = makeNode(CollateExpr);
newnode->arg = (Expr *) newexpr;
newnode->collOid = result_collid;
newnode->location = -1;
newexpr = (Node *) newnode;
}
}
/*
* Since there is now no trace of the function in the plan tree, we must
* explicitly record the plan's dependency on the function.
*/
if (context->root)
record_plan_function_dependency(context->root, funcid);
/*
* Recursively try to simplify the modified expression. Here we must add
* the current function to the context list of active functions.
*/
context->active_fns = lcons_oid(funcid, context->active_fns);
newexpr = eval_const_expressions_mutator(newexpr, context);
context->active_fns = list_delete_first(context->active_fns);
error_context_stack = sqlerrcontext.previous;
return (Expr *) newexpr;
/* Here if func is not inlinable: release temp memory and return NULL */
fail:
MemoryContextSwitchTo(oldcxt);
MemoryContextDelete(mycxt);
error_context_stack = sqlerrcontext.previous;
return NULL;
}
/*
* Replace Param nodes by appropriate actual parameters
*/
static Node *
substitute_actual_parameters(Node *expr, int nargs, List *args,
int *usecounts)
{
substitute_actual_parameters_context context;
context.nargs = nargs;
context.args = args;
context.usecounts = usecounts;
return substitute_actual_parameters_mutator(expr, &context);
}
static Node *
substitute_actual_parameters_mutator(Node *node,
substitute_actual_parameters_context *context)
{
if (node == NULL)
return NULL;
if (IsA(node, Param))
{
Param *param = (Param *) node;
if (param->paramkind != PARAM_EXTERN)
elog(ERROR, "unexpected paramkind: %d", (int) param->paramkind);
if (param->paramid <= 0 || param->paramid > context->nargs)
elog(ERROR, "invalid paramid: %d", param->paramid);
/* Count usage of parameter */
context->usecounts[param->paramid - 1]++;
/* Select the appropriate actual arg and replace the Param with it */
/* We don't need to copy at this time (it'll get done later) */
return list_nth(context->args, param->paramid - 1);
}
return expression_tree_mutator(node, substitute_actual_parameters_mutator,
(void *) context);
}
/*
* error context callback to let us supply a call-stack traceback
*/
static void
sql_inline_error_callback(void *arg)
{
inline_error_callback_arg *callback_arg = (inline_error_callback_arg *) arg;
int syntaxerrposition;
/* If it's a syntax error, convert to internal syntax error report */
syntaxerrposition = geterrposition();
if (syntaxerrposition > 0)
{
errposition(0);
internalerrposition(syntaxerrposition);
internalerrquery(callback_arg->prosrc);
}
errcontext("SQL function \"%s\" during inlining", callback_arg->proname);
}
/*
* evaluate_expr: pre-evaluate a constant expression
*
* We use the executor's routine ExecEvalExpr() to avoid duplication of
* code and ensure we get the same result as the executor would get.
*/
static Expr *
evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod,
Oid result_collation)
{
EState *estate;
ExprState *exprstate;
MemoryContext oldcontext;
Datum const_val;
bool const_is_null;
int16 resultTypLen;
bool resultTypByVal;
/*
* To use the executor, we need an EState.
*/
estate = CreateExecutorState();
/* We can use the estate's working context to avoid memory leaks. */
oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
/* Make sure any opfuncids are filled in. */
fix_opfuncids((Node *) expr);
/*
* Prepare expr for execution. (Note: we can't use ExecPrepareExpr
* because it'd result in recursively invoking eval_const_expressions.)
*/
exprstate = ExecInitExpr(expr, NULL);
/*
* And evaluate it.
*
* It is OK to use a default econtext because none of the ExecEvalExpr()
* code used in this situation will use econtext. That might seem
* fortuitous, but it's not so unreasonable --- a constant expression does
* not depend on context, by definition, n'est ce pas?
*/
const_val = ExecEvalExprSwitchContext(exprstate,
GetPerTupleExprContext(estate),
&const_is_null, NULL);
/* Get info needed about result datatype */
get_typlenbyval(result_type, &resultTypLen, &resultTypByVal);
/* Get back to outer memory context */
MemoryContextSwitchTo(oldcontext);
/*
* Must copy result out of sub-context used by expression eval.
*
* Also, if it's varlena, forcibly detoast it. This protects us against
* storing TOAST pointers into plans that might outlive the referenced
* data. (makeConst would handle detoasting anyway, but it's worth a few
* extra lines here so that we can do the copy and detoast in one step.)
*/
if (!const_is_null)
{
if (resultTypLen == -1)
const_val = PointerGetDatum(PG_DETOAST_DATUM_COPY(const_val));
else
const_val = datumCopy(const_val, resultTypByVal, resultTypLen);
}
/* Release all the junk we just created */
FreeExecutorState(estate);
/*
* Make the constant result node.
*/
return (Expr *) makeConst(result_type, result_typmod, result_collation,
resultTypLen,
const_val, const_is_null,
resultTypByVal);
}
/*
* inline_set_returning_function
* Attempt to "inline" a set-returning function in the FROM clause.
*
* "rte" is an RTE_FUNCTION rangetable entry. If it represents a call of a
* set-returning SQL function that can safely be inlined, expand the function
* and return the substitute Query structure. Otherwise, return NULL.
*
* This has a good deal of similarity to inline_function(), but that's
* for the non-set-returning case, and there are enough differences to
* justify separate functions.
*/
Query *
inline_set_returning_function(PlannerInfo *root, RangeTblEntry *rte)
{
RangeTblFunction *rtfunc;
FuncExpr *fexpr;
Oid func_oid;
HeapTuple func_tuple;
Form_pg_proc funcform;
char *src;
Datum tmp;
bool isNull;
bool modifyTargetList;
MemoryContext oldcxt;
MemoryContext mycxt;
List *saveInvalItems;
inline_error_callback_arg callback_arg;
ErrorContextCallback sqlerrcontext;
SQLFunctionParseInfoPtr pinfo;
List *raw_parsetree_list;
List *querytree_list;
Query *querytree;
Assert(rte->rtekind == RTE_FUNCTION);
/*
* It doesn't make a lot of sense for a SQL SRF to refer to itself in its
* own FROM clause, since that must cause infinite recursion at runtime.
* It will cause this code to recurse too, so check for stack overflow.
* (There's no need to do more.)
*/
check_stack_depth();
/* Fail if the RTE has ORDINALITY - we don't implement that here. */
if (rte->funcordinality)
return NULL;
/* Fail if RTE isn't a single, simple FuncExpr */
if (list_length(rte->functions) != 1)
return NULL;
rtfunc = (RangeTblFunction *) linitial(rte->functions);
if (!IsA(rtfunc->funcexpr, FuncExpr))
return NULL;
fexpr = (FuncExpr *) rtfunc->funcexpr;
func_oid = fexpr->funcid;
/*
* The function must be declared to return a set, else inlining would
* change the results if the contained SELECT didn't return exactly one
* row.
*/
if (!fexpr->funcretset)
return NULL;
/*
* Refuse to inline if the arguments contain any volatile functions or
* sub-selects. Volatile functions are rejected because inlining may
* result in the arguments being evaluated multiple times, risking a
* change in behavior. Sub-selects are rejected partly for implementation
* reasons (pushing them down another level might change their behavior)
* and partly because they're likely to be expensive and so multiple
* evaluation would be bad.
*/
if (contain_volatile_functions((Node *) fexpr->args) ||
contain_subplans((Node *) fexpr->args))
return NULL;
/* Check permission to call function (fail later, if not) */
if (pg_proc_aclcheck(func_oid, GetUserId(), ACL_EXECUTE) != ACLCHECK_OK)
return NULL;
/* Check whether a plugin wants to hook function entry/exit */
if (FmgrHookIsNeeded(func_oid))
return NULL;
/*
* OK, let's take a look at the function's pg_proc entry.
*/
func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(func_oid));
if (!HeapTupleIsValid(func_tuple))
elog(ERROR, "cache lookup failed for function %u", func_oid);
funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
/*
* Forget it if the function is not SQL-language or has other showstopper
* properties. In particular it mustn't be declared STRICT, since we
* couldn't enforce that. It also mustn't be VOLATILE, because that is
* supposed to cause it to be executed with its own snapshot, rather than
* sharing the snapshot of the calling query. (Rechecking proretset is
* just paranoia.)
*/
if (funcform->prolang != SQLlanguageId ||
funcform->proisstrict ||
funcform->provolatile == PROVOLATILE_VOLATILE ||
funcform->prosecdef ||
!funcform->proretset ||
!heap_attisnull(func_tuple, Anum_pg_proc_proconfig))
{
ReleaseSysCache(func_tuple);
return NULL;
}
/*
* Make a temporary memory context, so that we don't leak all the stuff
* that parsing might create.
*/
mycxt = AllocSetContextCreate(CurrentMemoryContext,
"inline_set_returning_function",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
oldcxt = MemoryContextSwitchTo(mycxt);
/*
* When we call eval_const_expressions below, it might try to add items to
* root->glob->invalItems. Since it is running in the temp context, those
* items will be in that context, and will need to be copied out if we're
* successful. Temporarily reset the list so that we can keep those items
* separate from the pre-existing list contents.
*/
saveInvalItems = root->glob->invalItems;
root->glob->invalItems = NIL;
/* Fetch the function body */
tmp = SysCacheGetAttr(PROCOID,
func_tuple,
Anum_pg_proc_prosrc,
&isNull);
if (isNull)
elog(ERROR, "null prosrc for function %u", func_oid);
src = TextDatumGetCString(tmp);
/*
* Setup error traceback support for ereport(). This is so that we can
* finger the function that bad information came from.
*/
callback_arg.proname = NameStr(funcform->proname);
callback_arg.prosrc = src;
sqlerrcontext.callback = sql_inline_error_callback;
sqlerrcontext.arg = (void *) &callback_arg;
sqlerrcontext.previous = error_context_stack;
error_context_stack = &sqlerrcontext;
/*
* Run eval_const_expressions on the function call. This is necessary to
* ensure that named-argument notation is converted to positional notation
* and any default arguments are inserted. It's a bit of overkill for the
* arguments, since they'll get processed again later, but no harm will be
* done.
*/
fexpr = (FuncExpr *) eval_const_expressions(root, (Node *) fexpr);
/* It should still be a call of the same function, but let's check */
if (!IsA(fexpr, FuncExpr) ||
fexpr->funcid != func_oid)
goto fail;
/* Arg list length should now match the function */
if (list_length(fexpr->args) != funcform->pronargs)
goto fail;
/*
* Set up to handle parameters while parsing the function body. We can
* use the FuncExpr just created as the input for
* prepare_sql_fn_parse_info.
*/
pinfo = prepare_sql_fn_parse_info(func_tuple,
(Node *) fexpr,
fexpr->inputcollid);
/*
* Parse, analyze, and rewrite (unlike inline_function(), we can't skip
* rewriting here). We can fail as soon as we find more than one query,
* though.
*/
raw_parsetree_list = pg_parse_query(src);
if (list_length(raw_parsetree_list) != 1)
goto fail;
querytree_list = pg_analyze_and_rewrite_params(linitial(raw_parsetree_list),
src,
(ParserSetupHook) sql_fn_parser_setup,
pinfo);
if (list_length(querytree_list) != 1)
goto fail;
querytree = linitial(querytree_list);
/*
* The single command must be a plain SELECT.
*/
if (!IsA(querytree, Query) ||
querytree->commandType != CMD_SELECT ||
querytree->utilityStmt)
goto fail;
/*
* Make sure the function (still) returns what it's declared to. This
* will raise an error if wrong, but that's okay since the function would
* fail at runtime anyway. Note that check_sql_fn_retval will also insert
* RelabelType(s) and/or NULL columns if needed to make the tlist
* expression(s) match the declared type of the function.
*
* If the function returns a composite type, don't inline unless the check
* shows it's returning a whole tuple result; otherwise what it's
* returning is a single composite column which is not what we need.
*/
if (!check_sql_fn_retval(func_oid, fexpr->funcresulttype,
querytree_list,
&modifyTargetList, NULL) &&
(get_typtype(fexpr->funcresulttype) == TYPTYPE_COMPOSITE ||
fexpr->funcresulttype == RECORDOID))
goto fail; /* reject not-whole-tuple-result cases */
/*
* If we had to modify the tlist to make it match, and the statement is
* one in which changing the tlist contents could change semantics, we
* have to punt and not inline.
*/
if (modifyTargetList)
goto fail;
/*
* If it returns RECORD, we have to check against the column type list
* provided in the RTE; check_sql_fn_retval can't do that. (If no match,
* we just fail to inline, rather than complaining; see notes for
* tlist_matches_coltypelist.) We don't have to do this for functions
* with declared OUT parameters, even though their funcresulttype is
* RECORDOID, so check get_func_result_type too.
*/
if (fexpr->funcresulttype == RECORDOID &&
get_func_result_type(func_oid, NULL, NULL) == TYPEFUNC_RECORD &&
!tlist_matches_coltypelist(querytree->targetList,
rtfunc->funccoltypes))
goto fail;
/*
* Looks good --- substitute parameters into the query.
*/
querytree = substitute_actual_srf_parameters(querytree,
funcform->pronargs,
fexpr->args);
/*
* Copy the modified query out of the temporary memory context, and clean
* up.
*/
MemoryContextSwitchTo(oldcxt);
querytree = copyObject(querytree);
/* copy up any new invalItems, too */
root->glob->invalItems = list_concat(saveInvalItems,
copyObject(root->glob->invalItems));
MemoryContextDelete(mycxt);
error_context_stack = sqlerrcontext.previous;
ReleaseSysCache(func_tuple);
/*
* We don't have to fix collations here because the upper query is already
* parsed, ie, the collations in the RTE are what count.
*/
/*
* Since there is now no trace of the function in the plan tree, we must
* explicitly record the plan's dependency on the function.
*/
record_plan_function_dependency(root, func_oid);
return querytree;
/* Here if func is not inlinable: release temp memory and return NULL */
fail:
MemoryContextSwitchTo(oldcxt);
root->glob->invalItems = saveInvalItems;
MemoryContextDelete(mycxt);
error_context_stack = sqlerrcontext.previous;
ReleaseSysCache(func_tuple);
return NULL;
}
/*
* Replace Param nodes by appropriate actual parameters
*
* This is just enough different from substitute_actual_parameters()
* that it needs its own code.
*/
static Query *
substitute_actual_srf_parameters(Query *expr, int nargs, List *args)
{
substitute_actual_srf_parameters_context context;
context.nargs = nargs;
context.args = args;
context.sublevels_up = 1;
return query_tree_mutator(expr,
substitute_actual_srf_parameters_mutator,
&context,
0);
}
static Node *
substitute_actual_srf_parameters_mutator(Node *node,
substitute_actual_srf_parameters_context *context)
{
Node *result;
if (node == NULL)
return NULL;
if (IsA(node, Query))
{
context->sublevels_up++;
result = (Node *) query_tree_mutator((Query *) node,
substitute_actual_srf_parameters_mutator,
(void *) context,
0);
context->sublevels_up--;
return result;
}
if (IsA(node, Param))
{
Param *param = (Param *) node;
if (param->paramkind == PARAM_EXTERN)
{
if (param->paramid <= 0 || param->paramid > context->nargs)
elog(ERROR, "invalid paramid: %d", param->paramid);
/*
* Since the parameter is being inserted into a subquery, we must
* adjust levels.
*/
result = copyObject(list_nth(context->args, param->paramid - 1));
IncrementVarSublevelsUp(result, context->sublevels_up, 0);
return result;
}
}
return expression_tree_mutator(node,
substitute_actual_srf_parameters_mutator,
(void *) context);
}
/*
* Check whether a SELECT targetlist emits the specified column types,
* to see if it's safe to inline a function returning record.
*
* We insist on exact match here. The executor allows binary-coercible
* cases too, but we don't have a way to preserve the correct column types
* in the correct places if we inline the function in such a case.
*
* Note that we only check type OIDs not typmods; this agrees with what the
* executor would do at runtime, and attributing a specific typmod to a
* function result is largely wishful thinking anyway.
*/
static bool
tlist_matches_coltypelist(List *tlist, List *coltypelist)
{
ListCell *tlistitem;
ListCell *clistitem;
clistitem = list_head(coltypelist);
foreach(tlistitem, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(tlistitem);
Oid coltype;
if (tle->resjunk)
continue; /* ignore junk columns */
if (clistitem == NULL)
return false; /* too many tlist items */
coltype = lfirst_oid(clistitem);
clistitem = lnext(clistitem);
if (exprType((Node *) tle->expr) != coltype)
return false; /* column type mismatch */
}
if (clistitem != NULL)
return false; /* too few tlist items */
return true;
}
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