diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index a2925ae4946..372eee20680 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -105,14 +105,12 @@ typedef enum NodeTag
  * - custom_query_jumble: Has custom implementation in queryjumblefuncs.c
  *   for the field of a node.  Also available as a node attribute.
  *
- * - query_jumble_ignore: Ignore the field for the query jumbling.  Note
- *   that typmod and collation information are usually irrelevant for the
- *   query jumbling.
+ * - query_jumble_ignore: Ignore the field for query jumbling.
  *
  * - query_jumble_squash: Squash multiple values during query jumbling.
  *
  * - query_jumble_location: Mark the field as a location to track.  This is
- *   only allowed for integer fields that include "location" in their name.
+ *   only used for fields of type ParseLoc, which otherwise are not jumbled.
  *
  * - read_as(VALUE): In nodeRead(), replace the field's value with VALUE.
  *
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index a1644322908..4133c404a6b 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -109,10 +109,13 @@ typedef uint64 AclMode;			/* a bitmask of privilege bits */
  *	  Planning converts a Query tree into a Plan tree headed by a PlannedStmt
  *	  node --- the Query structure is not used by the executor.
  *
- *	  All the fields ignored for the query jumbling are not semantically
- *	  significant (such as alias names), as is ignored anything that can
- *	  be deduced from child nodes (else we'd just be double-hashing that
- *	  piece of information).
+ *	  We ignore fields for query jumbling if they are not semantically
+ *	  significant (such as alias names).  We also ignore anything that can
+ *	  be deduced from other fields or child nodes, else we'd just be
+ *	  double-hashing that piece of information.  In some places query jumbling
+ *	  deliberately ignores fields that are semantically significant, such as
+ *	  Const values, because we have made a policy decision to combine queries
+ *	  that differ only in those respects.
  */
 typedef struct Query
 {
@@ -125,8 +128,8 @@ typedef struct Query
 
 	/*
 	 * query identifier (can be set by plugins); ignored for equal, as it
-	 * might not be set; also not stored.  This is the result of the query
-	 * jumble, hence ignored.
+	 * might not be set; also not stored.  This is the output of query
+	 * jumbling, hence it must be ignored as an input.
 	 *
 	 * We store this as a signed value as this is the form it's displayed to
 	 * users in places such as EXPLAIN and pg_stat_statements.  Primarily this
@@ -142,8 +145,7 @@ typedef struct Query
 
 	/*
 	 * rtable index of target relation for INSERT/UPDATE/DELETE/MERGE; 0 for
-	 * SELECT.  This is ignored in the query jumble as unrelated to the
-	 * compilation of the query ID.
+	 * SELECT.
 	 */
 	int			resultRelation pg_node_attr(query_jumble_ignore);
 
@@ -1818,7 +1820,7 @@ typedef struct CommonTableExpr
 
 	/*
 	 * Number of RTEs referencing this CTE (excluding internal
-	 * self-references), irrelevant for query jumbling.
+	 * self-references).
 	 */
 	int			cterefcount pg_node_attr(query_jumble_ignore);
 	/* list of output column names */
@@ -2359,7 +2361,7 @@ typedef struct SetOperationStmt
 	Node	   *rarg;			/* right child */
 	/* Eventually add fields for CORRESPONDING spec here */
 
-	/* Fields derived during parse analysis (irrelevant for query jumbling): */
+	/* Fields derived during parse analysis: */
 	/* OID list of output column type OIDs */
 	List	   *colTypes pg_node_attr(query_jumble_ignore);
 	/* integer list of output column typmods */
@@ -3735,8 +3737,6 @@ typedef struct InlineCodeBlock
  * list contains copies of the expressions for all output arguments, in the
  * order of the procedure's declared arguments.  (outargs is never evaluated,
  * but is useful to the caller as a reference for what to assign to.)
- * The transformed call state is not relevant in the query jumbling, only the
- * function call is.
  * ----------------------
  */
 typedef struct CallStmt