First cut at implementing IN (and NOT IN) via hashtables. There is

more to be done yet, but this is a good start.

1 files changed, 498 insertions, 10 deletions

diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index 40eca6749ec..d3f32913914 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSubplan.c,v 1.42 2003/01/10 21:08:08 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSubplan.c,v 1.43 2003/01/12 04:03:34 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,11 +22,24 @@
 #include "access/heapam.h"
 #include "executor/executor.h"
 #include "executor/nodeSubplan.h"
+#include "nodes/makefuncs.h"
+#include "parser/parse_expr.h"
 #include "tcop/pquery.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(node)
+ *		ExecSubPlan
  * ----------------------------------------------------------------
  */
 Datum
@@ -35,6 +48,155 @@ ExecSubPlan(SubPlanState *node,
 			bool *isNull)
 {
 	SubPlan	   *subplan = (SubPlan *) node->xprstate.expr;
+
+	if (subplan->setParam != NIL)
+		elog(ERROR, "ExecSubPlan: can't 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, "ExecHashSubPlan: 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 != NIL)
+		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;
@@ -52,9 +214,6 @@ ExecSubPlan(SubPlanState *node,
 	 */
 	oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
 
-	if (subplan->setParam != NIL)
-		elog(ERROR, "ExecSubPlan: can't set parent params from subquery");
-
 	/*
 	 * Set Params of this plan from parent plan correlation Vars
 	 */
@@ -267,6 +426,203 @@ ExecSubPlan(SubPlanState *node,
 	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 = 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,
+										  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,
+											  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;
+		List	   *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 = lfirsti(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(&hashiter);
+	while ((entry = ScanTupleHashTable(hashtable, &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
  * ----------------------------------------------------------------
@@ -289,8 +645,14 @@ ExecInitSubPlan(SubPlanState *node, EState *estate)
 	 */
 	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;
 
 	/*
 	 * create an EState for the subplan
@@ -343,6 +705,137 @@ ExecInitSubPlan(SubPlanState *node, EState *estate)
 		 * it, for others - it doesn't matter...
 		 */
 	}
+
+	/*
+	 * 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,
+				   *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 = 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 functions for the hash tables.
+		 */
+		lefttlist = righttlist = NIL;
+		leftptlist = rightptlist = NIL;
+		node->eqfunctions = (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;
+
+			Assert(IsA(fstate, FuncExprState));
+			Assert(IsA(opexpr, OpExpr));
+			Assert(length(fstate->args) == 2);
+
+			/* Process lefthand argument */
+			exstate = (ExprState *) lfirst(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->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->arg = exstate;
+			righttlist = lappend(righttlist, tlestate);
+			rightptlist = lappend(rightptlist, tle);
+
+			/* Lookup the combining function */
+			fmgr_info(opexpr->opfuncid, &node->eqfunctions[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);
+	}
 }
 
 /* ----------------------------------------------------------------
@@ -476,11 +969,6 @@ ExecEndSubPlan(SubPlanState *node)
 		node->planstate = NULL;
 		node->needShutdown = false;
 	}
-	if (node->curTuple)
-	{
-		heap_freetuple(node->curTuple);
-		node->curTuple = NULL;
-	}
 }
 
 void