Remove some unnecessary tests of pgstat_track_counts.

We may as well make pgstat_count_heap_scan() and related macros just count
whenever rel->pgstat_info isn't null.  Testing pgstat_track_counts buys
nothing at all in the normal case where that flag is ON; and when it's OFF,
the pgstat_info link will be null, so it's still a useless test.

This change is unlikely to buy any noticeable performance improvement,
but a cycle shaved is a cycle earned; and my investigations earlier today
convinced me that we're down to the point where individual instructions in
the inner execution loops are starting to matter.

src/backend/postmaster/pgstat.c

@@ -1660,7 +1660,7 @@ pgstat_count_heap_insert(Relation rel)
 {
 	PgStat_TableStatus *pgstat_info = rel->pgstat_info;
 
-	if (pgstat_track_counts && pgstat_info != NULL)
+	if (pgstat_info != NULL)
 	{
 		/* We have to log the effect at the proper transactional level */
 		int			nest_level = GetCurrentTransactionNestLevel();
@@ -1681,7 +1681,7 @@ pgstat_count_heap_update(Relation rel, bool hot)
 {
 	PgStat_TableStatus *pgstat_info = rel->pgstat_info;
 
-	if (pgstat_track_counts && pgstat_info != NULL)
+	if (pgstat_info != NULL)
 	{
 		/* We have to log the effect at the proper transactional level */
 		int			nest_level = GetCurrentTransactionNestLevel();
@@ -1706,7 +1706,7 @@ pgstat_count_heap_delete(Relation rel)
 {
 	PgStat_TableStatus *pgstat_info = rel->pgstat_info;
 
-	if (pgstat_track_counts && pgstat_info != NULL)
+	if (pgstat_info != NULL)
 	{
 		/* We have to log the effect at the proper transactional level */
 		int			nest_level = GetCurrentTransactionNestLevel();
@@ -1732,7 +1732,7 @@ pgstat_update_heap_dead_tuples(Relation rel, int delta)
 {
 	PgStat_TableStatus *pgstat_info = rel->pgstat_info;
 
-	if (pgstat_track_counts && pgstat_info != NULL)
+	if (pgstat_info != NULL)
 		pgstat_info->t_counts.t_delta_dead_tuples -= delta;
 }
 

src/include/pgstat.h

@@ -705,37 +705,37 @@ extern void pgstat_initstats(Relation rel);
 
 #define pgstat_count_heap_scan(rel)									\
 	do {															\
-		if (pgstat_track_counts && (rel)->pgstat_info != NULL)		\
+		if ((rel)->pgstat_info != NULL)								\
 			(rel)->pgstat_info->t_counts.t_numscans++;				\
 	} while (0)
 #define pgstat_count_heap_getnext(rel)								\
 	do {															\
-		if (pgstat_track_counts && (rel)->pgstat_info != NULL)		\
+		if ((rel)->pgstat_info != NULL)								\
 			(rel)->pgstat_info->t_counts.t_tuples_returned++;		\
 	} while (0)
 #define pgstat_count_heap_fetch(rel)								\
 	do {															\
-		if (pgstat_track_counts && (rel)->pgstat_info != NULL)		\
+		if ((rel)->pgstat_info != NULL)								\
 			(rel)->pgstat_info->t_counts.t_tuples_fetched++;		\
 	} while (0)
 #define pgstat_count_index_scan(rel)								\
 	do {															\
-		if (pgstat_track_counts && (rel)->pgstat_info != NULL)		\
+		if ((rel)->pgstat_info != NULL)								\
 			(rel)->pgstat_info->t_counts.t_numscans++;				\
 	} while (0)
 #define pgstat_count_index_tuples(rel, n)							\
 	do {															\
-		if (pgstat_track_counts && (rel)->pgstat_info != NULL)		\
+		if ((rel)->pgstat_info != NULL)								\
 			(rel)->pgstat_info->t_counts.t_tuples_returned += (n);	\
 	} while (0)
 #define pgstat_count_buffer_read(rel)								\
 	do {															\
-		if (pgstat_track_counts && (rel)->pgstat_info != NULL)		\
+		if ((rel)->pgstat_info != NULL)								\
 			(rel)->pgstat_info->t_counts.t_blocks_fetched++;		\
 	} while (0)
 #define pgstat_count_buffer_hit(rel)								\
 	do {															\
-		if (pgstat_track_counts && (rel)->pgstat_info != NULL)		\
+		if ((rel)->pgstat_info != NULL)								\
 			(rel)->pgstat_info->t_counts.t_blocks_hit++;			\
 	} while (0)