Use a hash table to speed up NOT IN(values)

Similar to 50e17ad28, which allowed hash tables to be used for IN clauses
with a set of constants, here we add the same feature for NOT IN clauses.

NOT IN evaluates the same as: WHERE a <> v1 AND a <> v2 AND a <> v3.
Obviously, if we're using a hash table we must be exactly equivalent to
that and return the same result taking into account that either side of
the condition could contain a NULL.  This requires a little bit of
special handling to make work with the hash table version.

When processing NOT IN, the ScalarArrayOpExpr's operator will be the <>
operator.  To be able to build and lookup a hash table we must use the
<>'s negator operator.  The planner checks if that exists and is hashable
and sets the relevant fields in ScalarArrayOpExpr to instruct the executor
to use hashing.

Author: David Rowley, James Coleman
Reviewed-by: James Coleman, Zhihong Yu
Discussion: https://postgr.es/m/CAApHDvoF1mum_FRk6D621edcB6KSHBi2+GAgWmioj5AhOu2vwQ@mail.gmail.com

src/backend/executor/execExpr.c

@@ -1205,19 +1205,34 @@ ExecInitExprRec(Expr *node, ExprState *state,
 				AclResult	aclresult;
 				FmgrInfo   *hash_finfo;
 				FunctionCallInfo hash_fcinfo;
+				Oid			cmpfuncid;
+
+				/*
+				 * Select the correct comparison function.  When we do hashed
+				 * NOT IN clauses, the opfuncid will be the inequality
+				 * comparison function and negfuncid will be set to equality.
+				 * We need to use the equality function for hash probes.
+				 */
+				if (OidIsValid(opexpr->negfuncid))
+				{
+					Assert(OidIsValid(opexpr->hashfuncid));
+					cmpfuncid = opexpr->negfuncid;
+				}
+				else
+					cmpfuncid = opexpr->opfuncid;
 
 				Assert(list_length(opexpr->args) == 2);
 				scalararg = (Expr *) linitial(opexpr->args);
 				arrayarg = (Expr *) lsecond(opexpr->args);
 
 				/* Check permission to call function */
-				aclresult = pg_proc_aclcheck(opexpr->opfuncid,
+				aclresult = pg_proc_aclcheck(cmpfuncid,
 											 GetUserId(),
 											 ACL_EXECUTE);
 				if (aclresult != ACLCHECK_OK)
 					aclcheck_error(aclresult, OBJECT_FUNCTION,
-								   get_func_name(opexpr->opfuncid));
-				InvokeFunctionExecuteHook(opexpr->opfuncid);
+								   get_func_name(cmpfuncid));
+				InvokeFunctionExecuteHook(cmpfuncid);
 
 				if (OidIsValid(opexpr->hashfuncid))
 				{
@@ -1233,7 +1248,7 @@ ExecInitExprRec(Expr *node, ExprState *state,
 				/* Set up the primary fmgr lookup information */
 				finfo = palloc0(sizeof(FmgrInfo));
 				fcinfo = palloc0(SizeForFunctionCallInfo(2));
-				fmgr_info(opexpr->opfuncid, finfo);
+				fmgr_info(cmpfuncid, finfo);
 				fmgr_info_set_expr((Node *) node, finfo);
 				InitFunctionCallInfoData(*fcinfo, finfo, 2,
 										 opexpr->inputcollid, NULL, NULL);
@@ -1274,6 +1289,7 @@ ExecInitExprRec(Expr *node, ExprState *state,
 
 					/* And perform the operation */
 					scratch.opcode = EEOP_HASHED_SCALARARRAYOP;
+					scratch.d.hashedscalararrayop.inclause = opexpr->useOr;
 					scratch.d.hashedscalararrayop.finfo = finfo;
 					scratch.d.hashedscalararrayop.fcinfo_data = fcinfo;
 					scratch.d.hashedscalararrayop.fn_addr = finfo->fn_addr;

src/backend/executor/execExprInterp.c

@@ -3493,6 +3493,7 @@ ExecEvalHashedScalarArrayOp(ExprState *state, ExprEvalStep *op, ExprContext *eco
 {
 	ScalarArrayOpExprHashTable *elements_tab = op->d.hashedscalararrayop.elements_tab;
 	FunctionCallInfo fcinfo = op->d.hashedscalararrayop.fcinfo_data;
+	bool		inclause = op->d.hashedscalararrayop.inclause;
 	bool		strictfunc = op->d.hashedscalararrayop.finfo->fn_strict;
 	Datum		scalar = fcinfo->args[0].value;
 	bool		scalar_isnull = fcinfo->args[0].isnull;
@@ -3596,7 +3597,12 @@ ExecEvalHashedScalarArrayOp(ExprState *state, ExprEvalStep *op, ExprContext *eco
 	/* Check the hash to see if we have a match. */
 	hashfound = NULL != saophash_lookup(elements_tab->hashtab, scalar);
 
-	result = BoolGetDatum(hashfound);
+	/* the result depends on if the clause is an IN or NOT IN clause */
+	if (inclause)
+		result = BoolGetDatum(hashfound);	/* IN */
+	else
+		result = BoolGetDatum(!hashfound);	/* NOT IN */
+
 	resultnull = false;
 
 	/*
@@ -3605,7 +3611,7 @@ ExecEvalHashedScalarArrayOp(ExprState *state, ExprEvalStep *op, ExprContext *eco
 	 * hashtable, but instead marked if we found any when building the table
 	 * in has_nulls.
 	 */
-	if (!DatumGetBool(result) && op->d.hashedscalararrayop.has_nulls)
+	if (!hashfound && op->d.hashedscalararrayop.has_nulls)
 	{
 		if (strictfunc)
 		{
@@ -3633,6 +3639,13 @@ ExecEvalHashedScalarArrayOp(ExprState *state, ExprEvalStep *op, ExprContext *eco
 
 			result = op->d.hashedscalararrayop.fn_addr(fcinfo);
 			resultnull = fcinfo->isnull;
+
+			/*
+			 * Reverse the result for NOT IN clauses since the above function
+			 * is the equality function and we need not-equals.
+			 */
+			if (!inclause)
+				result = !result;
 		}
 	}
 

src/backend/nodes/copyfuncs.c

@@ -1718,6 +1718,7 @@ _copyScalarArrayOpExpr(const ScalarArrayOpExpr *from)
 	COPY_SCALAR_FIELD(opno);
 	COPY_SCALAR_FIELD(opfuncid);
 	COPY_SCALAR_FIELD(hashfuncid);
+	COPY_SCALAR_FIELD(negfuncid);
 	COPY_SCALAR_FIELD(useOr);
 	COPY_SCALAR_FIELD(inputcollid);
 	COPY_NODE_FIELD(args);

src/backend/nodes/equalfuncs.c

@@ -414,6 +414,12 @@ _equalScalarArrayOpExpr(const ScalarArrayOpExpr *a, const ScalarArrayOpExpr *b)
 		b->hashfuncid != 0)
 		return false;
 
+	/* Likewise for the negfuncid */
+	if (a->negfuncid != b->negfuncid &&
+		a->negfuncid != 0 &&
+		b->negfuncid != 0)
+		return false;
+
 	COMPARE_SCALAR_FIELD(useOr);
 	COMPARE_SCALAR_FIELD(inputcollid);
 	COMPARE_NODE_FIELD(args);

src/backend/nodes/outfuncs.c

@@ -1311,6 +1311,7 @@ _outScalarArrayOpExpr(StringInfo str, const ScalarArrayOpExpr *node)
 	WRITE_OID_FIELD(opno);
 	WRITE_OID_FIELD(opfuncid);
 	WRITE_OID_FIELD(hashfuncid);
+	WRITE_OID_FIELD(negfuncid);
 	WRITE_BOOL_FIELD(useOr);
 	WRITE_OID_FIELD(inputcollid);
 	WRITE_NODE_FIELD(args);

src/backend/nodes/readfuncs.c

@@ -832,6 +832,7 @@ _readScalarArrayOpExpr(void)
 	READ_OID_FIELD(opno);
 	READ_OID_FIELD(opfuncid);
 	READ_OID_FIELD(hashfuncid);
+	READ_OID_FIELD(negfuncid);
 	READ_BOOL_FIELD(useOr);
 	READ_OID_FIELD(inputcollid);
 	READ_NODE_FIELD(args);

src/backend/optimizer/plan/setrefs.c

@@ -1687,6 +1687,9 @@ fix_expr_common(PlannerInfo *root, Node *node)
 
 		if (!OidIsValid(saop->hashfuncid))
 			record_plan_function_dependency(root, saop->hashfuncid);
+
+		if (!OidIsValid(saop->negfuncid))
+			record_plan_function_dependency(root, saop->negfuncid);
 	}
 	else if (IsA(node, Const))
 	{

src/backend/optimizer/prep/prepqual.c

@@ -128,6 +128,7 @@ negate_clause(Node *node)
 					newopexpr->opno = negator;
 					newopexpr->opfuncid = InvalidOid;
 					newopexpr->hashfuncid = InvalidOid;
+					newopexpr->negfuncid = InvalidOid;
 					newopexpr->useOr = !saopexpr->useOr;
 					newopexpr->inputcollid = saopexpr->inputcollid;
 					newopexpr->args = saopexpr->args;

src/backend/optimizer/util/clauses.c

@@ -2140,27 +2140,71 @@ convert_saop_to_hashed_saop_walker(Node *node, void *context)
 		Oid			lefthashfunc;
 		Oid			righthashfunc;
 
-		if (saop->useOr && arrayarg && IsA(arrayarg, Const) &&
-			!((Const *) arrayarg)->constisnull &&
-			get_op_hash_functions(saop->opno, &lefthashfunc, &righthashfunc) &&
-			lefthashfunc == righthashfunc)
+		if (arrayarg && IsA(arrayarg, Const) &&
+			!((Const *) arrayarg)->constisnull)
 		{
-			Datum		arrdatum = ((Const *) arrayarg)->constvalue;
-			ArrayType  *arr = (ArrayType *) DatumGetPointer(arrdatum);
-			int			nitems;
-
-			/*
-			 * Only fill in the hash functions if the array looks large enough
-			 * for it to be worth hashing instead of doing a linear search.
-			 */
-			nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
-
-			if (nitems >= MIN_ARRAY_SIZE_FOR_HASHED_SAOP)
+			if (saop->useOr)
 			{
-				/* Looks good. Fill in the hash functions */
-				saop->hashfuncid = lefthashfunc;
+				if (get_op_hash_functions(saop->opno, &lefthashfunc, &righthashfunc) &&
+					lefthashfunc == righthashfunc)
+				{
+					Datum		arrdatum = ((Const *) arrayarg)->constvalue;
+					ArrayType  *arr = (ArrayType *) DatumGetPointer(arrdatum);
+					int			nitems;
+
+					/*
+					 * Only fill in the hash functions if the array looks
+					 * large enough for it to be worth hashing instead of
+					 * doing a linear search.
+					 */
+					nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
+
+					if (nitems >= MIN_ARRAY_SIZE_FOR_HASHED_SAOP)
+					{
+						/* Looks good. Fill in the hash functions */
+						saop->hashfuncid = lefthashfunc;
+					}
+					return true;
+				}
+			}
+			else				/* !saop->useOr */
+			{
+				Oid			negator = get_negator(saop->opno);
+
+				/*
+				 * Check if this is a NOT IN using an operator whose negator
+				 * is hashable.  If so we can still build a hash table and
+				 * just ensure the lookup items are not in the hash table.
+				 */
+				if (OidIsValid(negator) &&
+					get_op_hash_functions(negator, &lefthashfunc, &righthashfunc) &&
+					lefthashfunc == righthashfunc)
+				{
+					Datum		arrdatum = ((Const *) arrayarg)->constvalue;
+					ArrayType  *arr = (ArrayType *) DatumGetPointer(arrdatum);
+					int			nitems;
+
+					/*
+					 * Only fill in the hash functions if the array looks
+					 * large enough for it to be worth hashing instead of
+					 * doing a linear search.
+					 */
+					nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
+
+					if (nitems >= MIN_ARRAY_SIZE_FOR_HASHED_SAOP)
+					{
+						/* Looks good. Fill in the hash functions */
+						saop->hashfuncid = lefthashfunc;
+
+						/*
+						 * Also set the negfuncid.  The executor will need
+						 * that to perform hashtable lookups.
+						 */
+						saop->negfuncid = get_opcode(negator);
+					}
+					return true;
+				}
 			}
-			return true;
 		}
 	}
 

src/backend/parser/parse_oper.c

@@ -895,6 +895,7 @@ make_scalar_array_op(ParseState *pstate, List *opname,
 	result->opno = oprid(tup);
 	result->opfuncid = opform->oprcode;
 	result->hashfuncid = InvalidOid;
+	result->negfuncid = InvalidOid;
 	result->useOr = useOr;
 	/* inputcollid will be set by parse_collate.c */
 	result->args = args;

src/backend/partitioning/partbounds.c

@@ -3878,6 +3878,7 @@ make_partition_op_expr(PartitionKey key, int keynum,
 					saopexpr->opno = operoid;
 					saopexpr->opfuncid = get_opcode(operoid);
 					saopexpr->hashfuncid = InvalidOid;
+					saopexpr->negfuncid = InvalidOid;
 					saopexpr->useOr = true;
 					saopexpr->inputcollid = key->partcollation[keynum];
 					saopexpr->args = list_make2(arg1, arrexpr);