[#25268] YSQL: Simplify ExecLockRows code

Summary:
The `ExecLockRows` function has the code to check that row locks are not requested for YB and non-YB tables at same time. It is reasonable to move this code into initialization step of the  Lock Rows node to avoid wasting of CPU cycles on each row processing.
Jira: DB-14457

Test Plan: Jenkins

Reviewers: pjain

Reviewed By: pjain

Subscribers: yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D40632

src/postgres/src/backend/executor/nodeLockRows.c

@@ -59,26 +59,9 @@ ExecLockRows(PlanState *pstate)
 lnext:
 	slot = ExecProcNode(outerPlan);
 
-	int n_yb_relations = 0;
-	int n_relations = 0;
-	foreach(lc, node->lr_arowMarks)
+	if (node->yb_are_row_marks_for_yb_rels &&
+		XactIsoLevel == XACT_SERIALIZABLE)
 	{
-		ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(lc);
-		ExecRowMark *erm = aerm->rowmark;
-		if (IsYBBackedRelation(erm->relation))
-		{
-			n_yb_relations++;
-		}
-		n_relations++;
-	}
-
-	if (n_yb_relations > 0 && n_yb_relations != n_relations)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("Mixing Yugabyte relations and not Yugabyte relations with "
-						"row locks is not supported")));
-
-	if (n_yb_relations > 0 && XactIsoLevel == XACT_SERIALIZABLE) {
 		/*
 		 * For YB relations, we don't lock tuples using this node in SERIALIZABLE level. Instead we take
 		 * predicate locks by setting the row mark in read requests sent to txn participants.
@@ -211,7 +194,9 @@ ExecLockRows(PlanState *pstate)
 		if (!IsolationUsesXactSnapshot())
 			lockflags |= TUPLE_LOCK_FLAG_FIND_LAST_VERSION;
 
-		if (IsYBBackedRelation(erm->relation))
+		Assert(
+			IsYBBackedRelation(erm->relation) == node->yb_are_row_marks_for_yb_rels);
+		if (node->yb_are_row_marks_for_yb_rels)
 		{
 			test = YBCLockTuple(
 				erm->relation, datum, erm->markType, erm->waitPolicy, estate);
@@ -398,6 +383,8 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 	 */
 	lrstate->lr_arowMarks = NIL;
 	epq_arowmarks = NIL;
+	bool row_lock_for_yb_rel_found = false;
+	bool row_lock_for_non_yb_rel_found = false;
 	foreach(lc, node->rowMarks)
 	{
 		PlanRowMark *rc = lfirst_node(PlanRowMark, lc);
@@ -419,11 +406,26 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 		 * do an EPQ recheck.
 		 */
 		if (RowMarkRequiresRowShareLock(erm->markType))
+		{
+			if (IsYBBackedRelation(erm->relation))
+				row_lock_for_yb_rel_found = true;
+			else
+				row_lock_for_non_yb_rel_found = true;
+
 			lrstate->lr_arowMarks = lappend(lrstate->lr_arowMarks, aerm);
+		}
 		else
 			epq_arowmarks = lappend(epq_arowmarks, aerm);
 	}
 
+	if (row_lock_for_yb_rel_found && row_lock_for_non_yb_rel_found)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("Mixing Yugabyte relations and not Yugabyte "
+						"relations with row locks is not supported")));
+
+	lrstate->yb_are_row_marks_for_yb_rels = row_lock_for_yb_rel_found;
+
 	/* Now we have the info needed to set up EPQ state */
 	EvalPlanQualInit(&lrstate->lr_epqstate, estate,
 					 outerPlan, epq_arowmarks, node->epqParam);

src/postgres/src/include/nodes/execnodes.h

@@ -2998,6 +2998,9 @@ typedef struct LockRowsState
 	PlanState	ps;				/* its first field is NodeTag */
 	List	   *lr_arowMarks;	/* List of ExecAuxRowMarks */
 	EPQState	lr_epqstate;	/* for evaluating EvalPlanQual rechecks */
+
+	bool 		yb_are_row_marks_for_yb_rels; /* lr_arowMarks relates to YB
+											   * relations */
 } LockRowsState;
 
 /* ----------------