Revert "Do execGrouping.c via expression eval machinery."

This reverts commit 773aec7aa98abd38d6d9435913bb8e14e392c274.

There's an unresolved issue in the reverted commit: It only creates
one comparator function, but in for the nodeSubplan.c case we need
more (c.f. FindTupleHashEntry vs LookupTupleHashEntry calls in
nodeSubplan.c).

This isn't too difficult to fix, but it's not entirely trivial
either. The fact that the issue only causes breakage on 32bit systems
shows that the current test coverage isn't that great.  To avoid
turning half the buildfarm red till those two issues are addressed,
revert.

1 files changed, 187 insertions, 49 deletions

diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index 4f604fb2861..8e8dbb1f205 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -52,33 +52,172 @@ static int	TupleHashTableMatch(struct tuplehash_hash *tb, const MinimalTuple tup
  *****************************************************************************/
 
 /*
- * execTuplesMatchPrepare
- *		Build expression that can be evaluated using ExecQual(), returning
- *		whether an ExprContext's inner/outer tuples are NOT DISTINCT
+ * execTuplesMatch
+ *		Return true if two tuples match in all the indicated fields.
+ *
+ * This actually implements SQL's notion of "not distinct".  Two nulls
+ * match, a null and a not-null don't match.
+ *
+ * slot1, slot2: the tuples to compare (must have same columns!)
+ * numCols: the number of attributes to be examined
+ * matchColIdx: array of attribute column numbers
+ * eqFunctions: array of fmgr lookup info for the equality functions to use
+ * evalContext: short-term memory context for executing the functions
+ *
+ * NB: evalContext is reset each time!
+ */
+bool
+execTuplesMatch(TupleTableSlot *slot1,
+				TupleTableSlot *slot2,
+				int numCols,
+				AttrNumber *matchColIdx,
+				FmgrInfo *eqfunctions,
+				MemoryContext evalContext)
+{
+	MemoryContext oldContext;
+	bool		result;
+	int			i;
+
+	/* Reset and switch into the temp context. */
+	MemoryContextReset(evalContext);
+	oldContext = MemoryContextSwitchTo(evalContext);
+
+	/*
+	 * We cannot report a match without checking all the fields, but we can
+	 * report a non-match as soon as we find unequal fields.  So, start
+	 * comparing at the last field (least significant sort key). That's the
+	 * most likely to be different if we are dealing with sorted input.
+	 */
+	result = true;
+
+	for (i = numCols; --i >= 0;)
+	{
+		AttrNumber	att = matchColIdx[i];
+		Datum		attr1,
+					attr2;
+		bool		isNull1,
+					isNull2;
+
+		attr1 = slot_getattr(slot1, att, &isNull1);
+
+		attr2 = slot_getattr(slot2, att, &isNull2);
+
+		if (isNull1 != isNull2)
+		{
+			result = false;		/* one null and one not; they aren't equal */
+			break;
+		}
+
+		if (isNull1)
+			continue;			/* both are null, treat as equal */
+
+		/* Apply the type-specific equality function */
+
+		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+										attr1, attr2)))
+		{
+			result = false;		/* they aren't equal */
+			break;
+		}
+	}
+
+	MemoryContextSwitchTo(oldContext);
+
+	return result;
+}
+
+/*
+ * execTuplesUnequal
+ *		Return true if two tuples are definitely unequal in the indicated
+ *		fields.
+ *
+ * Nulls are neither equal nor unequal to anything else.  A true result
+ * is obtained only if there are non-null fields that compare not-equal.
+ *
+ * Parameters are identical to execTuplesMatch.
  */
-ExprState *
-execTuplesMatchPrepare(TupleDesc desc,
-					   int numCols,
-					   AttrNumber *keyColIdx,
-					   Oid *eqOperators,
-					   PlanState *parent)
+bool
+execTuplesUnequal(TupleTableSlot *slot1,
+				  TupleTableSlot *slot2,
+				  int numCols,
+				  AttrNumber *matchColIdx,
+				  FmgrInfo *eqfunctions,
+				  MemoryContext evalContext)
 {
-	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
+	MemoryContext oldContext;
+	bool		result;
 	int			i;
-	ExprState  *expr;
 
-	if (numCols == 0)
-		return NULL;
+	/* Reset and switch into the temp context. */
+	MemoryContextReset(evalContext);
+	oldContext = MemoryContextSwitchTo(evalContext);
+
+	/*
+	 * We cannot report a match without checking all the fields, but we can
+	 * report a non-match as soon as we find unequal fields.  So, start
+	 * comparing at the last field (least significant sort key). That's the
+	 * most likely to be different if we are dealing with sorted input.
+	 */
+	result = false;
+
+	for (i = numCols; --i >= 0;)
+	{
+		AttrNumber	att = matchColIdx[i];
+		Datum		attr1,
+					attr2;
+		bool		isNull1,
+					isNull2;
+
+		attr1 = slot_getattr(slot1, att, &isNull1);
+
+		if (isNull1)
+			continue;			/* can't prove anything here */
+
+		attr2 = slot_getattr(slot2, att, &isNull2);
+
+		if (isNull2)
+			continue;			/* can't prove anything here */
+
+		/* Apply the type-specific equality function */
+
+		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+										attr1, attr2)))
+		{
+			result = true;		/* they are unequal */
+			break;
+		}
+	}
+
+	MemoryContextSwitchTo(oldContext);
+
+	return result;
+}
+
+
+/*
+ * execTuplesMatchPrepare
+ *		Look up the equality functions needed for execTuplesMatch or
+ *		execTuplesUnequal, given an array of equality operator OIDs.
+ *
+ * The result is a palloc'd array.
+ */
+FmgrInfo *
+execTuplesMatchPrepare(int numCols,
+					   Oid *eqOperators)
+{
+	FmgrInfo   *eqFunctions = (FmgrInfo *) palloc(numCols * sizeof(FmgrInfo));
+	int			i;
 
-	/* lookup equality functions */
 	for (i = 0; i < numCols; i++)
-		eqFunctions[i] = get_opcode(eqOperators[i]);
+	{
+		Oid			eq_opr = eqOperators[i];
+		Oid			eq_function;
 
-	/* build actual expression */
-	expr = ExecBuildGroupingEqual(desc, numCols, keyColIdx, eqFunctions,
-								  parent);
+		eq_function = get_opcode(eq_opr);
+		fmgr_info(eq_function, &eqFunctions[i]);
+	}
 
-	return expr;
+	return eqFunctions;
 }
 
 /*
@@ -149,9 +288,7 @@ execTuplesHashPrepare(int numCols,
  * storage that will live as long as the hashtable does.
  */
 TupleHashTable
-BuildTupleHashTable(PlanState *parent,
-					TupleDesc inputDesc,
-					int numCols, AttrNumber *keyColIdx,
+BuildTupleHashTable(int numCols, AttrNumber *keyColIdx,
 					FmgrInfo *eqfunctions,
 					FmgrInfo *hashfunctions,
 					long nbuckets, Size additionalsize,
@@ -160,9 +297,6 @@ BuildTupleHashTable(PlanState *parent,
 {
 	TupleHashTable hashtable;
 	Size		entrysize = sizeof(TupleHashEntryData) + additionalsize;
-	MemoryContext oldcontext;
-	Oid		   *eqoids = (Oid *) palloc(numCols * sizeof(Oid));
-	int			i;
 
 	Assert(nbuckets > 0);
 
@@ -199,26 +333,6 @@ BuildTupleHashTable(PlanState *parent,
 
 	hashtable->hashtab = tuplehash_create(tablecxt, nbuckets, hashtable);
 
-	oldcontext = MemoryContextSwitchTo(hashtable->tablecxt);
-
-	/*
-	 * We copy the input tuple descriptor just for safety --- we assume all
-	 * input tuples will have equivalent descriptors.
-	 */
-	hashtable->tableslot = MakeSingleTupleTableSlot(CreateTupleDescCopy(inputDesc));
-
-	/* build comparator for all columns */
-	for (i = 0; i < numCols; i++)
-		eqoids[i] = eqfunctions[i].fn_oid;
-	hashtable->eq_func = ExecBuildGroupingEqual(inputDesc,
-												numCols,
-												keyColIdx, eqoids,
-												parent);
-
-	MemoryContextSwitchTo(oldcontext);
-
-	hashtable->exprcontext = CreateExprContext(parent->state);
-
 	return hashtable;
 }
 
@@ -243,6 +357,22 @@ LookupTupleHashEntry(TupleHashTable hashtable, TupleTableSlot *slot,
 	bool		found;
 	MinimalTuple key;
 
+	/* If first time through, clone the input slot to make table slot */
+	if (hashtable->tableslot == NULL)
+	{
+		TupleDesc	tupdesc;
+
+		oldContext = MemoryContextSwitchTo(hashtable->tablecxt);
+
+		/*
+		 * We copy the input tuple descriptor just for safety --- we assume
+		 * all input tuples will have equivalent descriptors.
+		 */
+		tupdesc = CreateTupleDescCopy(slot->tts_tupleDescriptor);
+		hashtable->tableslot = MakeSingleTupleTableSlot(tupdesc);
+		MemoryContextSwitchTo(oldContext);
+	}
+
 	/* Need to run the hash functions in short-lived context */
 	oldContext = MemoryContextSwitchTo(hashtable->tempcxt);
 
@@ -394,6 +524,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
  * See whether two tuples (presumably of the same hash value) match
  *
  * As above, the passed pointers are pointers to TupleHashEntryData.
+ *
+ * Also, the caller must select an appropriate memory context for running
+ * the compare functions.  (dynahash.c doesn't change CurrentMemoryContext.)
  */
 static int
 TupleHashTableMatch(struct tuplehash_hash *tb, const MinimalTuple tuple1, const MinimalTuple tuple2)
@@ -401,7 +534,6 @@ TupleHashTableMatch(struct tuplehash_hash *tb, const MinimalTuple tuple1, const
 	TupleTableSlot *slot1;
 	TupleTableSlot *slot2;
 	TupleHashTable hashtable = (TupleHashTable) tb->private_data;
-	ExprContext *econtext = hashtable->exprcontext;
 
 	/*
 	 * We assume that simplehash.h will only ever call us with the first
@@ -416,7 +548,13 @@ TupleHashTableMatch(struct tuplehash_hash *tb, const MinimalTuple tuple1, const
 	slot2 = hashtable->inputslot;
 
 	/* For crosstype comparisons, the inputslot must be first */
-	econtext->ecxt_innertuple = slot1;
-	econtext->ecxt_outertuple = slot2;
-	return !ExecQualAndReset(hashtable->eq_func, econtext);
+	if (execTuplesMatch(slot2,
+						slot1,
+						hashtable->numCols,
+						hashtable->keyColIdx,
+						hashtable->cur_eq_funcs,
+						hashtable->tempcxt))
+		return 0;
+	else
+		return 1;
 }