database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-05-11 05:41:32 +03:00
Code
postgres/src/backend/optimizer/util/clauses.c
Joe Conway b26e3d660d Make RLS work with UPDATE ... WHERE CURRENT OF 
UPDATE ... WHERE CURRENT OF would not work in conjunction with
RLS. Arrange to allow the CURRENT OF expression to be pushed down.
Issue noted by Peter Geoghegan. Patch by Dean Rasheed. Back patch
to 9.5 where RLS was introduced.
2015-07-24 12:55:30 -07:00

5076 lines
149 KiB
C
Raw Blame History

/*-------------------------------------------------------------------------
*
* 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 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 */
}
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 (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;
Assert(ntest->argisrow);
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;
}
newntest = makeNode(NullTest);
newntest->arg = (Expr *) relem;
newntest->nulltesttype = ntest->nulltesttype;
newntest->argisrow = type_is_rowtype(exprType(relem));
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.
*/
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;
}
View Git Blame Copy Permalink