diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 2ca25d857d..d895ed29d1 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -841,8 +841,8 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 
 	/*
 	 * Allocate an array to store open Relations of each rangeTable item.  We
-	 * 0 fill this for now.  The Relations are only opened and stored here the
-	 * first time they're required during node initialization.
+	 * zero-fill this for now.  The Relations are only opened and stored here
+	 * the first time they're required during node initialization.
 	 */
 	estate->es_relations = (Relation *) palloc0(estate->es_range_table_size *
 												sizeof(Relation));
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index ab46fd425d..bd306d0389 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -994,8 +994,9 @@ ExecInitRangeTable(EState *estate, List *rangeTable)
 		if (rte->rtekind == RTE_RELATION && OidIsValid(rte->relid))
 		{
 			/*
-			 * The following asserts that no new lock needed to be taken,
-			 * meaning the upstream code already acquired the needed locks.
+			 * The following asserts that the necessary lock on the relation
+			 * has already been taken.  That can only however be true in the
+			 * parallel leader.
 			 */
 			Assert(rte->lockmode != NoLock);
 			if (!IsParallelWorker() &&
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index a9cfd1f67b..cbee07aeb8 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -1283,8 +1283,10 @@ addRangeTableEntryForRelation(ParseState *pstate,
 	Assert(pstate != NULL);
 
 #ifdef USE_ASSERT_CHECKING
-	if (lockmode != NoLock && !CheckRelationLockedByUs(RelationGetRelid(rel), lockmode))
-		elog(WARNING, "lock on \"%s\" is not held", RelationGetRelationName(rel));
+	if (lockmode != NoLock &&
+		!CheckRelationLockedByUs(RelationGetRelid(rel), lockmode))
+		elog(WARNING, "lock on \"%s\" is not held",
+			 RelationGetRelationName(rel));
 #endif
 
 	rte->rtekind = RTE_RELATION;
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index d844e323f0..2a265d591d 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -977,7 +977,10 @@ typedef struct RangeTblEntry
 	 */
 	Oid			relid;			/* OID of the relation */
 	char		relkind;		/* relation kind (see pg_class.relkind) */
-	LOCKMODE	lockmode;		/* lock level to obtain on the relation */
+	LOCKMODE	lockmode;		/* lock level to obtain on the relation; must
+								 * be non-zero for all plain relation RTEs
+								 * that will be passed to the executor via
+								 * PlannedStmt. */
 	struct TableSampleClause *tablesample;	/* sampling info, or NULL */
 
 	/*