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postgres/src/backend/executor/nodeSubplan.c
Bruce Momjian b6b71b85bc Pgindent run for 8.0.
2004-08-29 05:07:03 +00:00

1101 lines
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/*-------------------------------------------------------------------------
*
* nodeSubplan.c
* routines to support subselects
*
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeSubplan.c,v 1.65 2004/08/29 05:06:42 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecSubPlan - process a subselect
* ExecInitSubPlan - initialize a subselect
* ExecEndSubPlan - shut down a subselect
*/
#include "postgres.h"
#include "access/heapam.h"
#include "executor/executor.h"
#include "executor/nodeSubplan.h"
#include "nodes/makefuncs.h"
#include "parser/parse_expr.h"
#include "utils/array.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
static Datum ExecHashSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull);
static Datum ExecScanSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull);
static void buildSubPlanHash(SubPlanState *node);
static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot);
static bool tupleAllNulls(HeapTuple tuple);
/* ----------------------------------------------------------------
* ExecSubPlan
* ----------------------------------------------------------------
*/
Datum
ExecSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
/* Set default values for result flags: non-null, not a set result */
*isNull = false;
if (isDone)
*isDone = ExprSingleResult;
if (subplan->setParam != NIL)
elog(ERROR, "cannot set parent params from subquery");
if (subplan->useHashTable)
return ExecHashSubPlan(node, econtext, isNull);
else
return ExecScanSubPlan(node, econtext, isNull);
}
/*
* ExecHashSubPlan: store subselect result in an in-memory hash table
*/
static Datum
ExecHashSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
ExprContext *innerecontext = node->innerecontext;
TupleTableSlot *slot;
HeapTuple tup;
/* Shouldn't have any direct correlation Vars */
if (subplan->parParam != NIL || node->args != NIL)
elog(ERROR, "hashed subplan with direct correlation not supported");
/*
* If first time through or we need to rescan the subplan, build the
* hash table.
*/
if (node->hashtable == NULL || planstate->chgParam != NULL)
buildSubPlanHash(node);
/*
* The result for an empty subplan is always FALSE; no need to
* evaluate lefthand side.
*/
*isNull = false;
if (!node->havehashrows && !node->havenullrows)
return BoolGetDatum(false);
/*
* Evaluate lefthand expressions and form a projection tuple. First we
* have to set the econtext to use (hack alert!).
*/
node->projLeft->pi_exprContext = econtext;
slot = ExecProject(node->projLeft, NULL);
tup = slot->val;
/*
* Note: because we are typically called in a per-tuple context, we
* have to explicitly clear the projected tuple before returning.
* Otherwise, we'll have a double-free situation: the per-tuple
* context will probably be reset before we're called again, and then
* the tuple slot will think it still needs to free the tuple.
*/
/*
* Since the hashtable routines will use innerecontext's per-tuple
* memory as working memory, be sure to reset it for each tuple.
*/
ResetExprContext(innerecontext);
/*
* If the LHS is all non-null, probe for an exact match in the main
* hash table. If we find one, the result is TRUE. Otherwise, scan
* the partly-null table to see if there are any rows that aren't
* provably unequal to the LHS; if so, the result is UNKNOWN. (We
* skip that part if we don't care about UNKNOWN.) Otherwise, the
* result is FALSE.
*
* Note: the reason we can avoid a full scan of the main hash table is
* that the combining operators are assumed never to yield NULL when
* both inputs are non-null. If they were to do so, we might need to
* produce UNKNOWN instead of FALSE because of an UNKNOWN result in
* comparing the LHS to some main-table entry --- which is a
* comparison we will not even make, unless there's a chance match of
* hash keys.
*/
if (HeapTupleNoNulls(tup))
{
if (node->havehashrows &&
LookupTupleHashEntry(node->hashtable, slot, NULL) != NULL)
{
ExecClearTuple(slot);
return BoolGetDatum(true);
}
if (node->havenullrows &&
findPartialMatch(node->hashnulls, slot))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
ExecClearTuple(slot);
return BoolGetDatum(false);
}
/*
* When the LHS is partly or wholly NULL, we can never return TRUE. If
* we don't care about UNKNOWN, just return FALSE. Otherwise, if the
* LHS is wholly NULL, immediately return UNKNOWN. (Since the
* combining operators are strict, the result could only be FALSE if
* the sub-select were empty, but we already handled that case.)
* Otherwise, we must scan both the main and partly-null tables to see
* if there are any rows that aren't provably unequal to the LHS; if
* so, the result is UNKNOWN. Otherwise, the result is FALSE.
*/
if (node->hashnulls == NULL)
{
ExecClearTuple(slot);
return BoolGetDatum(false);
}
if (tupleAllNulls(tup))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
/* Scan partly-null table first, since more likely to get a match */
if (node->havenullrows &&
findPartialMatch(node->hashnulls, slot))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
if (node->havehashrows &&
findPartialMatch(node->hashtable, slot))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
ExecClearTuple(slot);
return BoolGetDatum(false);
}
/*
* ExecScanSubPlan: default case where we have to rescan subplan each time
*/
static Datum
ExecScanSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
SubLinkType subLinkType = subplan->subLinkType;
bool useOr = subplan->useOr;
MemoryContext oldcontext;
TupleTableSlot *slot;
Datum result;
bool found = false; /* TRUE if got at least one subplan tuple */
ListCell *pvar;
ListCell *l;
ArrayBuildState *astate = NULL;
/*
* We are probably in a short-lived expression-evaluation context.
* Switch to the child plan's per-query context for manipulating its
* chgParam, calling ExecProcNode on it, etc.
*/
oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
/*
* Set Params of this plan from parent plan correlation values. (Any
* calculation we have to do is done in the parent econtext, since the
* Param values don't need to have per-query lifetime.)
*/
Assert(list_length(subplan->parParam) == list_length(node->args));
forboth(l, subplan->parParam, pvar, node->args)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
econtext,
&(prm->isnull),
NULL);
planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
}
ExecReScan(planstate, NULL);
/*
* For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the
* result is boolean as are the results of the combining operators. We
* combine results within a tuple (if there are multiple columns)
* using OR semantics if "useOr" is true, AND semantics if not. We
* then combine results across tuples (if the subplan produces more
* than one) using OR semantics for ANY_SUBLINK or AND semantics for
* ALL_SUBLINK. (MULTIEXPR_SUBLINK doesn't allow multiple tuples from
* the subplan.) NULL results from the combining operators are handled
* according to the usual SQL semantics for OR and AND. The result
* for no input tuples is FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK,
* NULL for MULTIEXPR_SUBLINK.
*
* For EXPR_SUBLINK we require the subplan to produce no more than one
* tuple, else an error is raised. For ARRAY_SUBLINK we allow the
* subplan to produce more than one tuple. In either case, if zero
* tuples are produced, we return NULL. Assuming we get a tuple, we
* just use its first column (there can be only one non-junk column in
* this case).
*/
result = BoolGetDatum(subLinkType == ALL_SUBLINK);
*isNull = false;
for (slot = ExecProcNode(planstate);
!TupIsNull(slot);
slot = ExecProcNode(planstate))
{
HeapTuple tup = slot->val;
TupleDesc tdesc = slot->ttc_tupleDescriptor;
Datum rowresult = BoolGetDatum(!useOr);
bool rownull = false;
int col = 1;
ListCell *plst;
if (subLinkType == EXISTS_SUBLINK)
{
found = true;
result = BoolGetDatum(true);
break;
}
if (subLinkType == EXPR_SUBLINK)
{
/* cannot allow multiple input tuples for EXPR sublink */
if (found)
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("more than one row returned by a subquery used as an expression")));
found = true;
/*
* We need to copy the subplan's tuple in case the result is
* of pass-by-ref type --- our return value will point into
* this copied tuple! Can't use the subplan's instance of the
* tuple since it won't still be valid after next
* ExecProcNode() call. node->curTuple keeps track of the
* copied tuple for eventual freeing.
*/
MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
tup = heap_copytuple(tup);
if (node->curTuple)
heap_freetuple(node->curTuple);
node->curTuple = tup;
MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
result = heap_getattr(tup, col, tdesc, isNull);
/* keep scanning subplan to make sure there's only one tuple */
continue;
}
if (subLinkType == ARRAY_SUBLINK)
{
Datum dvalue;
bool disnull;
found = true;
/* stash away current value */
dvalue = heap_getattr(tup, 1, tdesc, &disnull);
astate = accumArrayResult(astate, dvalue, disnull,
tdesc->attrs[0]->atttypid,
oldcontext);
/* keep scanning subplan to collect all values */
continue;
}
/* cannot allow multiple input tuples for MULTIEXPR sublink either */
if (subLinkType == MULTIEXPR_SUBLINK && found)
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("more than one row returned by a subquery used as an expression")));
found = true;
/*
* For ALL, ANY, and MULTIEXPR sublinks, iterate over combining
* operators for columns of tuple.
*/
Assert(list_length(node->exprs) == list_length(subplan->paramIds));
forboth(l, node->exprs, plst, subplan->paramIds)
{
ExprState *exprstate = (ExprState *) lfirst(l);
int paramid = lfirst_int(plst);
ParamExecData *prmdata;
Datum expresult;
bool expnull;
/*
* Load up the Param representing this column of the
* sub-select.
*/
prmdata = &(econtext->ecxt_param_exec_vals[paramid]);
Assert(prmdata->execPlan == NULL);
prmdata->value = heap_getattr(tup, col, tdesc,
&(prmdata->isnull));
/*
* Now we can eval the combining operator for this column.
*/
expresult = ExecEvalExprSwitchContext(exprstate, econtext,
&expnull, NULL);
/*
* Combine the result into the row result as appropriate.
*/
if (col == 1)
{
rowresult = expresult;
rownull = expnull;
}
else if (useOr)
{
/* combine within row per OR semantics */
if (expnull)
rownull = true;
else if (DatumGetBool(expresult))
{
rowresult = BoolGetDatum(true);
rownull = false;
break; /* needn't look at any more columns */
}
}
else
{
/* combine within row per AND semantics */
if (expnull)
rownull = true;
else if (!DatumGetBool(expresult))
{
rowresult = BoolGetDatum(false);
rownull = false;
break; /* needn't look at any more columns */
}
}
col++;
}
if (subLinkType == ANY_SUBLINK)
{
/* combine across rows per OR semantics */
if (rownull)
*isNull = true;
else if (DatumGetBool(rowresult))
{
result = BoolGetDatum(true);
*isNull = false;
break; /* needn't look at any more rows */
}
}
else if (subLinkType == ALL_SUBLINK)
{
/* combine across rows per AND semantics */
if (rownull)
*isNull = true;
else if (!DatumGetBool(rowresult))
{
result = BoolGetDatum(false);
*isNull = false;
break; /* needn't look at any more rows */
}
}
else
{
/* must be MULTIEXPR_SUBLINK */
result = rowresult;
*isNull = rownull;
}
}
if (!found)
{
/*
* deal with empty subplan result. result/isNull were previously
* initialized correctly for all sublink types except EXPR, ARRAY,
* and MULTIEXPR; for those, return NULL.
*/
if (subLinkType == EXPR_SUBLINK ||
subLinkType == ARRAY_SUBLINK ||
subLinkType == MULTIEXPR_SUBLINK)
{
result = (Datum) 0;
*isNull = true;
}
}
else if (subLinkType == ARRAY_SUBLINK)
{
Assert(astate != NULL);
/* We return the result in the caller's context */
result = makeArrayResult(astate, oldcontext);
}
MemoryContextSwitchTo(oldcontext);
return result;
}
/*
* buildSubPlanHash: load hash table by scanning subplan output.
*/
static void
buildSubPlanHash(SubPlanState *node)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
int ncols = list_length(node->exprs);
ExprContext *innerecontext = node->innerecontext;
MemoryContext tempcxt = innerecontext->ecxt_per_tuple_memory;
MemoryContext oldcontext;
int nbuckets;
TupleTableSlot *slot;
Assert(subplan->subLinkType == ANY_SUBLINK);
Assert(!subplan->useOr);
/*
* If we already had any hash tables, destroy 'em; then create empty
* hash table(s).
*
* If we need to distinguish accurately between FALSE and UNKNOWN (i.e.,
* NULL) results of the IN operation, then we have to store subplan
* output rows that are partly or wholly NULL. We store such rows in
* a separate hash table that we expect will be much smaller than the
* main table. (We can use hashing to eliminate partly-null rows that
* are not distinct. We keep them separate to minimize the cost of
* the inevitable full-table searches; see findPartialMatch.)
*
* If it's not necessary to distinguish FALSE and UNKNOWN, then we don't
* need to store subplan output rows that contain NULL.
*/
MemoryContextReset(node->tablecxt);
node->hashtable = NULL;
node->hashnulls = NULL;
node->havehashrows = false;
node->havenullrows = false;
nbuckets = (int) ceil(planstate->plan->plan_rows);
if (nbuckets < 1)
nbuckets = 1;
node->hashtable = BuildTupleHashTable(ncols,
node->keyColIdx,
node->eqfunctions,
node->hashfunctions,
nbuckets,
sizeof(TupleHashEntryData),
node->tablecxt,
tempcxt);
if (!subplan->unknownEqFalse)
{
if (ncols == 1)
nbuckets = 1; /* there can only be one entry */
else
{
nbuckets /= 16;
if (nbuckets < 1)
nbuckets = 1;
}
node->hashnulls = BuildTupleHashTable(ncols,
node->keyColIdx,
node->eqfunctions,
node->hashfunctions,
nbuckets,
sizeof(TupleHashEntryData),
node->tablecxt,
tempcxt);
}
/*
* We are probably in a short-lived expression-evaluation context.
* Switch to the child plan's per-query context for calling
* ExecProcNode.
*/
oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
/*
* Reset subplan to start.
*/
ExecReScan(planstate, NULL);
/*
* Scan the subplan and load the hash table(s). Note that when there
* are duplicate rows coming out of the sub-select, only one copy is
* stored.
*/
for (slot = ExecProcNode(planstate);
!TupIsNull(slot);
slot = ExecProcNode(planstate))
{
HeapTuple tup = slot->val;
TupleDesc tdesc = slot->ttc_tupleDescriptor;
int col = 1;
ListCell *plst;
bool isnew;
/*
* Load up the Params representing the raw sub-select outputs,
* then form the projection tuple to store in the hashtable.
*/
foreach(plst, subplan->paramIds)
{
int paramid = lfirst_int(plst);
ParamExecData *prmdata;
prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]);
Assert(prmdata->execPlan == NULL);
prmdata->value = heap_getattr(tup, col, tdesc,
&(prmdata->isnull));
col++;
}
slot = ExecProject(node->projRight, NULL);
tup = slot->val;
/*
* If result contains any nulls, store separately or not at all.
* (Since we know the projection tuple has no junk columns, we can
* just look at the overall hasnull info bit, instead of groveling
* through the columns.)
*/
if (HeapTupleNoNulls(tup))
{
(void) LookupTupleHashEntry(node->hashtable, slot, &isnew);
node->havehashrows = true;
}
else if (node->hashnulls)
{
(void) LookupTupleHashEntry(node->hashnulls, slot, &isnew);
node->havenullrows = true;
}
/*
* Reset innerecontext after each inner tuple to free any memory
* used in hash computation or comparison routines.
*/
ResetExprContext(innerecontext);
}
/*
* Since the projected tuples are in the sub-query's context and not
* the main context, we'd better clear the tuple slot before there's
* any chance of a reset of the sub-query's context. Else we will
* have the potential for a double free attempt.
*/
ExecClearTuple(node->projRight->pi_slot);
MemoryContextSwitchTo(oldcontext);
}
/*
* findPartialMatch: does the hashtable contain an entry that is not
* provably distinct from the tuple?
*
* We have to scan the whole hashtable; we can't usefully use hashkeys
* to guide probing, since we might get partial matches on tuples with
* hashkeys quite unrelated to what we'd get from the given tuple.
*/
static bool
findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot)
{
int numCols = hashtable->numCols;
AttrNumber *keyColIdx = hashtable->keyColIdx;
HeapTuple tuple = slot->val;
TupleDesc tupdesc = slot->ttc_tupleDescriptor;
TupleHashIterator hashiter;
TupleHashEntry entry;
ResetTupleHashIterator(hashtable, &hashiter);
while ((entry = ScanTupleHashTable(&hashiter)) != NULL)
{
if (!execTuplesUnequal(entry->firstTuple,
tuple,
tupdesc,
numCols, keyColIdx,
hashtable->eqfunctions,
hashtable->tempcxt))
return true;
}
return false;
}
/*
* tupleAllNulls: is the tuple completely NULL?
*/
static bool
tupleAllNulls(HeapTuple tuple)
{
int ncols = tuple->t_data->t_natts;
int i;
for (i = 1; i <= ncols; i++)
{
if (!heap_attisnull(tuple, i))
return false;
}
return true;
}
/* ----------------------------------------------------------------
* ExecInitSubPlan
* ----------------------------------------------------------------
*/
void
ExecInitSubPlan(SubPlanState *node, EState *estate)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
EState *sp_estate;
MemoryContext oldcontext;
/*
* Do access checking on the rangetable entries in the subquery.
*/
ExecCheckRTPerms(subplan->rtable);
/*
* initialize my state
*/
node->needShutdown = false;
node->curTuple = NULL;
node->projLeft = NULL;
node->projRight = NULL;
node->hashtable = NULL;
node->hashnulls = NULL;
node->tablecxt = NULL;
node->innerecontext = NULL;
node->keyColIdx = NULL;
node->eqfunctions = NULL;
node->hashfunctions = NULL;
/*
* create an EState for the subplan
*
* The subquery needs its own EState because it has its own rangetable.
* It shares our Param ID space, however. XXX if rangetable access
* were done differently, the subquery could share our EState, which
* would eliminate some thrashing about in this module...
*/
sp_estate = CreateExecutorState();
node->sub_estate = sp_estate;
oldcontext = MemoryContextSwitchTo(sp_estate->es_query_cxt);
sp_estate->es_range_table = subplan->rtable;
sp_estate->es_param_list_info = estate->es_param_list_info;
sp_estate->es_param_exec_vals = estate->es_param_exec_vals;
sp_estate->es_tupleTable =
ExecCreateTupleTable(ExecCountSlotsNode(subplan->plan) + 10);
sp_estate->es_snapshot = estate->es_snapshot;
sp_estate->es_crosscheck_snapshot = estate->es_crosscheck_snapshot;
sp_estate->es_instrument = estate->es_instrument;
/*
* Start up the subplan (this is a very cut-down form of InitPlan())
*/
node->planstate = ExecInitNode(subplan->plan, sp_estate);
node->needShutdown = true; /* now we need to shutdown the subplan */
MemoryContextSwitchTo(oldcontext);
/*
* If this plan is un-correlated or undirect correlated one and want
* to set params for parent plan then mark parameters as needing
* evaluation.
*
* Note that in the case of un-correlated subqueries we don't care about
* setting parent->chgParam here: indices take care about it, for
* others - it doesn't matter...
*/
if (subplan->setParam != NIL)
{
ListCell *lst;
foreach(lst, subplan->setParam)
{
int paramid = lfirst_int(lst);
ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
prm->execPlan = node;
}
}
/*
* If we are going to hash the subquery output, initialize relevant
* stuff. (We don't create the hashtable until needed, though.)
*/
if (subplan->useHashTable)
{
int ncols,
i;
TupleDesc tupDesc;
TupleTable tupTable;
TupleTableSlot *slot;
List *lefttlist,
*righttlist,
*leftptlist,
*rightptlist;
ListCell *lexpr;
/* We need a memory context to hold the hash table(s) */
node->tablecxt =
AllocSetContextCreate(CurrentMemoryContext,
"Subplan HashTable Context",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/* and a short-lived exprcontext for function evaluation */
node->innerecontext = CreateExprContext(estate);
/* Silly little array of column numbers 1..n */
ncols = list_length(node->exprs);
node->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
for (i = 0; i < ncols; i++)
node->keyColIdx[i] = i + 1;
/*
* We use ExecProject to evaluate the lefthand and righthand
* expression lists and form tuples. (You might think that we
* could use the sub-select's output tuples directly, but that is
* not the case if we had to insert any run-time coercions of the
* sub-select's output datatypes; anyway this avoids storing any
* resjunk columns that might be in the sub-select's output.) Run
* through the combining expressions to build tlists for the
* lefthand and righthand sides. We need both the ExprState list
* (for ExecProject) and the underlying parse Exprs (for
* ExecTypeFromTL).
*
* We also extract the combining operators themselves to initialize
* the equality and hashing functions for the hash tables.
*/
lefttlist = righttlist = NIL;
leftptlist = rightptlist = NIL;
node->eqfunctions = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
node->hashfunctions = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
i = 1;
foreach(lexpr, node->exprs)
{
FuncExprState *fstate = (FuncExprState *) lfirst(lexpr);
OpExpr *opexpr = (OpExpr *) fstate->xprstate.expr;
ExprState *exstate;
Expr *expr;
TargetEntry *tle;
GenericExprState *tlestate;
Oid hashfn;
Assert(IsA(fstate, FuncExprState));
Assert(IsA(opexpr, OpExpr));
Assert(list_length(fstate->args) == 2);
/* Process lefthand argument */
exstate = (ExprState *) linitial(fstate->args);
expr = exstate->expr;
tle = makeTargetEntry(makeResdom(i,
exprType((Node *) expr),
exprTypmod((Node *) expr),
NULL,
false),
expr);
tlestate = makeNode(GenericExprState);
tlestate->xprstate.expr = (Expr *) tle;
tlestate->xprstate.evalfunc = NULL;
tlestate->arg = exstate;
lefttlist = lappend(lefttlist, tlestate);
leftptlist = lappend(leftptlist, tle);
/* Process righthand argument */
exstate = (ExprState *) lsecond(fstate->args);
expr = exstate->expr;
tle = makeTargetEntry(makeResdom(i,
exprType((Node *) expr),
exprTypmod((Node *) expr),
NULL,
false),
expr);
tlestate = makeNode(GenericExprState);
tlestate->xprstate.expr = (Expr *) tle;
tlestate->xprstate.evalfunc = NULL;
tlestate->arg = exstate;
righttlist = lappend(righttlist, tlestate);
rightptlist = lappend(rightptlist, tle);
/* Lookup the combining function */
fmgr_info(opexpr->opfuncid, &node->eqfunctions[i - 1]);
node->eqfunctions[i - 1].fn_expr = (Node *) opexpr;
/* Lookup the associated hash function */
hashfn = get_op_hash_function(opexpr->opno);
if (!OidIsValid(hashfn))
elog(ERROR, "could not find hash function for hash operator %u",
opexpr->opno);
fmgr_info(hashfn, &node->hashfunctions[i - 1]);
i++;
}
/*
* Create a tupletable to hold these tuples. (Note: we never
* bother to free the tupletable explicitly; that's okay because
* it will never store raw disk tuples that might have associated
* buffer pins. The only resource involved is memory, which will
* be cleaned up by freeing the query context.)
*/
tupTable = ExecCreateTupleTable(2);
/*
* Construct tupdescs, slots and projection nodes for left and
* right sides. The lefthand expressions will be evaluated in the
* parent plan node's exprcontext, which we don't have access to
* here. Fortunately we can just pass NULL for now and fill it in
* later (hack alert!). The righthand expressions will be
* evaluated in our own innerecontext.
*/
tupDesc = ExecTypeFromTL(leftptlist, false);
slot = ExecAllocTableSlot(tupTable);
ExecSetSlotDescriptor(slot, tupDesc, true);
node->projLeft = ExecBuildProjectionInfo(lefttlist,
NULL,
slot);
tupDesc = ExecTypeFromTL(rightptlist, false);
slot = ExecAllocTableSlot(tupTable);
ExecSetSlotDescriptor(slot, tupDesc, true);
node->projRight = ExecBuildProjectionInfo(righttlist,
node->innerecontext,
slot);
}
}
/* ----------------------------------------------------------------
* ExecSetParamPlan
*
* Executes an InitPlan subplan and sets its output parameters.
*
* This is called from ExecEvalParam() when the value of a PARAM_EXEC
* parameter is requested and the param's execPlan field is set (indicating
* that the param has not yet been evaluated). This allows lazy evaluation
* of initplans: we don't run the subplan until/unless we need its output.
* Note that this routine MUST clear the execPlan fields of the plan's
* output parameters after evaluating them!
* ----------------------------------------------------------------
*/
void
ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
SubLinkType subLinkType = subplan->subLinkType;
MemoryContext oldcontext;
TupleTableSlot *slot;
ListCell *l;
bool found = false;
ArrayBuildState *astate = NULL;
/*
* Must switch to child query's per-query memory context.
*/
oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
if (subLinkType == ANY_SUBLINK ||
subLinkType == ALL_SUBLINK)
elog(ERROR, "ANY/ALL subselect unsupported as initplan");
if (planstate->chgParam != NULL)
ExecReScan(planstate, NULL);
for (slot = ExecProcNode(planstate);
!TupIsNull(slot);
slot = ExecProcNode(planstate))
{
HeapTuple tup = slot->val;
TupleDesc tdesc = slot->ttc_tupleDescriptor;
int i = 1;
if (subLinkType == EXISTS_SUBLINK)
{
/* There can be only one param... */
int paramid = linitial_int(subplan->setParam);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = BoolGetDatum(true);
prm->isnull = false;
found = true;
break;
}
if (subLinkType == ARRAY_SUBLINK)
{
Datum dvalue;
bool disnull;
found = true;
/* stash away current value */
dvalue = heap_getattr(tup, 1, tdesc, &disnull);
astate = accumArrayResult(astate, dvalue, disnull,
tdesc->attrs[0]->atttypid,
oldcontext);
/* keep scanning subplan to collect all values */
continue;
}
if (found &&
(subLinkType == EXPR_SUBLINK ||
subLinkType == MULTIEXPR_SUBLINK))
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("more than one row returned by a subquery used as an expression")));
found = true;
/*
* We need to copy the subplan's tuple into our own context, in
* case any of the params are pass-by-ref type --- the pointers
* stored in the param structs will point at this copied tuple!
* node->curTuple keeps track of the copied tuple for eventual
* freeing.
*/
MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
tup = heap_copytuple(tup);
if (node->curTuple)
heap_freetuple(node->curTuple);
node->curTuple = tup;
MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
/*
* Now set all the setParam params from the columns of the tuple
*/
foreach(l, subplan->setParam)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = heap_getattr(tup, i, tdesc, &(prm->isnull));
i++;
}
}
if (!found)
{
if (subLinkType == EXISTS_SUBLINK)
{
/* There can be only one param... */
int paramid = linitial_int(subplan->setParam);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = BoolGetDatum(false);
prm->isnull = false;
}
else
{
foreach(l, subplan->setParam)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = (Datum) 0;
prm->isnull = true;
}
}
}
else if (subLinkType == ARRAY_SUBLINK)
{
/* There can be only one param... */
int paramid = linitial_int(subplan->setParam);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
Assert(astate != NULL);
prm->execPlan = NULL;
/* We build the result in query context so it won't disappear */
prm->value = makeArrayResult(astate, econtext->ecxt_per_query_memory);
prm->isnull = false;
}
MemoryContextSwitchTo(oldcontext);
}
/* ----------------------------------------------------------------
* ExecEndSubPlan
* ----------------------------------------------------------------
*/
void
ExecEndSubPlan(SubPlanState *node)
{
if (node->needShutdown)
{
MemoryContext oldcontext;
oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
ExecEndPlan(node->planstate, node->sub_estate);
MemoryContextSwitchTo(oldcontext);
FreeExecutorState(node->sub_estate);
node->sub_estate = NULL;
node->planstate = NULL;
node->needShutdown = false;
}
}
/*
* Mark an initplan as needing recalculation
*/
void
ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
{
PlanState *planstate = node->planstate;
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
EState *estate = parent->state;
ListCell *l;
/* sanity checks */
if (subplan->parParam != NIL)
elog(ERROR, "direct correlated subquery unsupported as initplan");
if (subplan->setParam == NIL)
elog(ERROR, "setParam list of initplan is empty");
if (bms_is_empty(planstate->plan->extParam))
elog(ERROR, "extParam set of initplan is empty");
/*
* Don't actually re-scan: ExecSetParamPlan does it if needed.
*/
/*
* Mark this subplan's output parameters as needing recalculation
*/
foreach(l, subplan->setParam)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
prm->execPlan = node;
parent->chgParam = bms_add_member(parent->chgParam, paramid);
}
}
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