Move heaprel struct field next to index rel field.

Commit 61b313e4 added a heaprel struct member to IndexVacuumInfo, but
placed it last.  Move the heaprel struct member next to the index struct
member to improve the code's readability.

Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WznG=TV6S9d3VA=y0vBHbXwnLs9_LLdiML=aNJuHeriwxg@mail.gmail.com

src/backend/access/heap/vacuumlazy.c

@@ -2711,13 +2711,13 @@ lazy_vacuum_one_index(Relation indrel, IndexBulkDeleteResult *istat,
 	LVSavedErrInfo saved_err_info;
 
 	ivinfo.index = indrel;
+	ivinfo.heaprel = vacrel->rel;
 	ivinfo.analyze_only = false;
 	ivinfo.report_progress = false;
 	ivinfo.estimated_count = true;
 	ivinfo.message_level = DEBUG2;
 	ivinfo.num_heap_tuples = reltuples;
 	ivinfo.strategy = vacrel->bstrategy;
-	ivinfo.heaprel = vacrel->rel;
 
 	/*
 	 * Update error traceback information.
@@ -2760,6 +2760,7 @@ lazy_cleanup_one_index(Relation indrel, IndexBulkDeleteResult *istat,
 	LVSavedErrInfo saved_err_info;
 
 	ivinfo.index = indrel;
+	ivinfo.heaprel = vacrel->rel;
 	ivinfo.analyze_only = false;
 	ivinfo.report_progress = false;
 	ivinfo.estimated_count = estimated_count;
@@ -2767,7 +2768,6 @@ lazy_cleanup_one_index(Relation indrel, IndexBulkDeleteResult *istat,
 
 	ivinfo.num_heap_tuples = reltuples;
 	ivinfo.strategy = vacrel->bstrategy;
-	ivinfo.heaprel = vacrel->rel;
 
 	/*
 	 * Update error traceback information.

src/backend/catalog/index.c

@@ -3358,13 +3358,13 @@ validate_index(Oid heapId, Oid indexId, Snapshot snapshot)
 	 * Scan the index and gather up all the TIDs into a tuplesort object.
 	 */
 	ivinfo.index = indexRelation;
+	ivinfo.heaprel = heapRelation;
 	ivinfo.analyze_only = false;
 	ivinfo.report_progress = true;
 	ivinfo.estimated_count = true;
 	ivinfo.message_level = DEBUG2;
 	ivinfo.num_heap_tuples = heapRelation->rd_rel->reltuples;
 	ivinfo.strategy = NULL;
-	ivinfo.heaprel = heapRelation;
 
 	/*
 	 * Encode TIDs as int8 values for the sort, rather than directly sorting

src/backend/commands/analyze.c

@@ -707,12 +707,12 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 			IndexVacuumInfo ivinfo;
 
 			ivinfo.index = Irel[ind];
+			ivinfo.heaprel = onerel;
 			ivinfo.analyze_only = true;
 			ivinfo.estimated_count = true;
 			ivinfo.message_level = elevel;
 			ivinfo.num_heap_tuples = onerel->rd_rel->reltuples;
 			ivinfo.strategy = vac_strategy;
-			ivinfo.heaprel = onerel;
 
 			stats = index_vacuum_cleanup(&ivinfo, NULL);
 

src/backend/commands/vacuumparallel.c

@@ -836,13 +836,13 @@ parallel_vacuum_process_one_index(ParallelVacuumState *pvs, Relation indrel,
 		istat = &(indstats->istat);
 
 	ivinfo.index = indrel;
+	ivinfo.heaprel = pvs->heaprel;
 	ivinfo.analyze_only = false;
 	ivinfo.report_progress = false;
 	ivinfo.message_level = DEBUG2;
 	ivinfo.estimated_count = pvs->shared->estimated_count;
 	ivinfo.num_heap_tuples = pvs->shared->reltuples;
 	ivinfo.strategy = pvs->bstrategy;
-	ivinfo.heaprel = pvs->heaprel;
 
 	/* Update error traceback information */
 	pvs->indname = pstrdup(RelationGetRelationName(indrel));

src/include/access/genam.h

@@ -44,13 +44,13 @@ typedef struct IndexBuildResult
 typedef struct IndexVacuumInfo
 {
 	Relation	index;			/* the index being vacuumed */
+	Relation	heaprel;		/* the heap relation the index belongs to */
 	bool		analyze_only;	/* ANALYZE (without any actual vacuum) */
 	bool		report_progress;	/* emit progress.h status reports */
 	bool		estimated_count;	/* num_heap_tuples is an estimate */
 	int			message_level;	/* ereport level for progress messages */
 	double		num_heap_tuples;	/* tuples remaining in heap */
 	BufferAccessStrategy strategy;	/* access strategy for reads */
-	Relation	heaprel;		/* the heap relation the index belongs to */
 } IndexVacuumInfo;
 
 /*