Rename apply_at to apply_agg_at for clarity

The field name "apply_at" in RelAggInfo was a bit ambiguous.  Rename
it to "apply_agg_at" to improve clarity and make its purpose clearer.

Per complaint from David Rowley, Robert Haas.

Suggested-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CA+TgmoZ0KR2_XCWHy17=HHcQ3p2Mamc9c6Dnnhf1J6wPYFD9ng@mail.gmail.com

src/backend/optimizer/path/allpaths.c

@@ -3449,7 +3449,7 @@ generate_grouped_paths(PlannerInfo *root, RelOptInfo *grouped_rel,
 	 * We push partial aggregation only to the lowest possible level in the
 	 * join tree that is deemed useful.
 	 */
-	if (!bms_equal(agg_info->apply_at, rel->relids) ||
+	if (!bms_equal(agg_info->apply_agg_at, rel->relids) ||
 		!agg_info->agg_useful)
 		return;
 

src/backend/optimizer/path/joinrels.c

@@ -922,7 +922,7 @@ make_grouped_join_rel(PlannerInfo *root, RelOptInfo *rel1,
 	RelOptInfo *grouped_rel2;
 	bool		rel1_empty;
 	bool		rel2_empty;
-	Relids		agg_apply_at;
+	Relids		apply_agg_at;
 
 	/*
 	 * If there are no aggregate expressions or grouping expressions, eager
@@ -979,9 +979,9 @@ make_grouped_join_rel(PlannerInfo *root, RelOptInfo *rel1,
 									   rel1_empty ? rel1 : grouped_rel1,
 									   rel2_empty ? rel2 : grouped_rel2,
 									   sjinfo, restrictlist);
-			agg_info->apply_at = rel1_empty ?
-				grouped_rel2->agg_info->apply_at :
-				grouped_rel1->agg_info->apply_at;
+			agg_info->apply_agg_at = rel1_empty ?
+				grouped_rel2->agg_info->apply_agg_at :
+				grouped_rel1->agg_info->apply_agg_at;
 		}
 		else
 		{
@@ -995,7 +995,7 @@ make_grouped_join_rel(PlannerInfo *root, RelOptInfo *rel1,
 			 * constructed by joining other input relations.
 			 */
 			grouped_rel->rows = agg_info->grouped_rows;
-			agg_info->apply_at = bms_copy(joinrel->relids);
+			agg_info->apply_agg_at = bms_copy(joinrel->relids);
 		}
 
 		grouped_rel->agg_info = agg_info;
@@ -1019,9 +1019,9 @@ make_grouped_join_rel(PlannerInfo *root, RelOptInfo *rel1,
 	 * Get the set of relids where partial aggregation is applied among the
 	 * given input relations.
 	 */
-	agg_apply_at = rel1_empty ?
-		grouped_rel2->agg_info->apply_at :
-		grouped_rel1->agg_info->apply_at;
+	apply_agg_at = rel1_empty ?
+		grouped_rel2->agg_info->apply_agg_at :
+		grouped_rel1->agg_info->apply_agg_at;
 
 	/*
 	 * If it's not the designated level, skip building grouped paths.
@@ -1037,16 +1037,16 @@ make_grouped_join_rel(PlannerInfo *root, RelOptInfo *rel1,
 	 * level and still valid for partial aggregation, we update the designated
 	 * level to (B C), and adjust the size estimates accordingly.
 	 */
-	if (!bms_equal(agg_apply_at, grouped_rel->agg_info->apply_at))
+	if (!bms_equal(apply_agg_at, grouped_rel->agg_info->apply_agg_at))
 	{
-		if (bms_is_subset(agg_apply_at, grouped_rel->agg_info->apply_at))
+		if (bms_is_subset(apply_agg_at, grouped_rel->agg_info->apply_agg_at))
 		{
 			/* Adjust the size estimates for the grouped join relation. */
 			set_joinrel_size_estimates(root, grouped_rel,
 									   rel1_empty ? rel1 : grouped_rel1,
 									   rel2_empty ? rel2 : grouped_rel2,
 									   sjinfo, restrictlist);
-			grouped_rel->agg_info->apply_at = agg_apply_at;
+			grouped_rel->agg_info->apply_agg_at = apply_agg_at;
 		}
 		else
 			return;

src/backend/optimizer/util/relnode.c

@@ -462,7 +462,7 @@ build_simple_grouped_rel(PlannerInfo *root, RelOptInfo *rel)
 		return NULL;
 
 	/* Track the set of relids at which partial aggregation is applied */
-	agg_info->apply_at = bms_copy(rel->relids);
+	agg_info->apply_agg_at = bms_copy(rel->relids);
 
 	/* build the grouped relation */
 	grouped_rel = build_grouped_rel(root, rel);
@@ -2692,7 +2692,7 @@ create_rel_agg_info(PlannerInfo *root, RelOptInfo *rel,
 											  rel,
 											  rel->top_parent);
 
-		agg_info->apply_at = NULL;	/* caller will change this later */
+		agg_info->apply_agg_at = NULL;	/* caller will change this later */
 
 		if (calculate_grouped_rows)
 		{
@@ -2759,7 +2759,7 @@ create_rel_agg_info(PlannerInfo *root, RelOptInfo *rel,
 	result->agg_input = agg_input;
 	result->group_clauses = group_clauses;
 	result->group_exprs = group_exprs;
-	result->apply_at = NULL;	/* caller will change this later */
+	result->apply_agg_at = NULL;	/* caller will change this later */
 
 	if (calculate_grouped_rows)
 	{

src/include/nodes/pathnodes.h

@@ -1178,8 +1178,8 @@ typedef struct RelOptInfo
  * "group_clauses" and "group_exprs" are lists of SortGroupClauses and the
  * corresponding grouping expressions.
  *
- * "apply_at" tracks the set of relids at which partial aggregation is applied
- * in the paths of this grouped relation.
+ * "apply_agg_at" tracks the set of relids at which partial aggregation is
+ * applied in the paths of this grouped relation.
  *
  * "grouped_rows" is the estimated number of result tuples of the grouped
  * relation.
@@ -1206,7 +1206,7 @@ typedef struct RelAggInfo
 	List	   *group_exprs;
 
 	/* the set of relids partial aggregation is applied at */
-	Relids		apply_at;
+	Relids		apply_agg_at;
 
 	/* estimated number of result tuples */
 	Cardinality grouped_rows;