Generate pg_stat_get_xact*() functions for relations using macros

This change replaces seven functions definitions by macros.

This is the same idea as 8018ffb or 83a1a1b, taking advantage of the
variable rename done in 8089517 for relation entries.

Author: Bertrand Drouvot
Discussion: https://postgr.es/m/631e3084-c5d9-8463-7540-fcff4674caa5@gmail.com

Author: michaelpq

src/backend/utils/adt/pgstatfuncs.c

@@ -1498,50 +1498,42 @@ pg_stat_get_slru(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
-Datum
-pg_stat_get_xact_numscans(PG_FUNCTION_ARGS)
-{
-	Oid			relid = PG_GETARG_OID(0);
-	int64		result;
-	PgStat_TableStatus *tabentry;
-
-	if ((tabentry = find_tabstat_entry(relid)) == NULL)
-		result = 0;
-	else
-		result = (int64) (tabentry->counts.numscans);
-
-	PG_RETURN_INT64(result);
+#define PG_STAT_GET_XACT_RELENTRY_INT64(stat)			\
+Datum													\
+CppConcat(pg_stat_get_xact_,stat)(PG_FUNCTION_ARGS)		\
+{														\
+	Oid         relid = PG_GETARG_OID(0);				\
+	int64       result;									\
+	PgStat_TableStatus *tabentry;						\
+														\
+	if ((tabentry = find_tabstat_entry(relid)) == NULL)	\
+		result = 0;										\
+	else												\
+		result = (int64) (tabentry->counts.stat);		\
+														\
+	PG_RETURN_INT64(result);							\
 }
 
-Datum
-pg_stat_get_xact_tuples_returned(PG_FUNCTION_ARGS)
-{
-	Oid			relid = PG_GETARG_OID(0);
-	int64		result;
-	PgStat_TableStatus *tabentry;
+/* pg_stat_get_xact_numscans */
+PG_STAT_GET_XACT_RELENTRY_INT64(numscans)
 
-	if ((tabentry = find_tabstat_entry(relid)) == NULL)
-		result = 0;
-	else
-		result = (int64) (tabentry->counts.tuples_returned);
+/* pg_stat_get_xact_tuples_returned */
+PG_STAT_GET_XACT_RELENTRY_INT64(tuples_returned)
 
-	PG_RETURN_INT64(result);
-}
+/* pg_stat_get_xact_tuples_fetched */
+PG_STAT_GET_XACT_RELENTRY_INT64(tuples_fetched)
 
-Datum
-pg_stat_get_xact_tuples_fetched(PG_FUNCTION_ARGS)
-{
-	Oid			relid = PG_GETARG_OID(0);
-	int64		result;
-	PgStat_TableStatus *tabentry;
+/* pg_stat_get_xact_tuples_hot_updated */
+PG_STAT_GET_XACT_RELENTRY_INT64(tuples_hot_updated)
 
-	if ((tabentry = find_tabstat_entry(relid)) == NULL)
-		result = 0;
-	else
-		result = (int64) (tabentry->counts.tuples_fetched);
+/* pg_stat_get_xact_tuples_newpage_updated */
+PG_STAT_GET_XACT_RELENTRY_INT64(tuples_newpage_updated)
 
-	PG_RETURN_INT64(result);
-}
+/* pg_stat_get_xact_blocks_fetched */
+PG_STAT_GET_XACT_RELENTRY_INT64(blocks_fetched)
+
+/* pg_stat_get_xact_blocks_hit */
+PG_STAT_GET_XACT_RELENTRY_INT64(blocks_hit)
 
 Datum
 pg_stat_get_xact_tuples_inserted(PG_FUNCTION_ARGS)
@@ -1606,66 +1598,6 @@ pg_stat_get_xact_tuples_deleted(PG_FUNCTION_ARGS)
 	PG_RETURN_INT64(result);
 }
 
-Datum
-pg_stat_get_xact_tuples_hot_updated(PG_FUNCTION_ARGS)
-{
-	Oid			relid = PG_GETARG_OID(0);
-	int64		result;
-	PgStat_TableStatus *tabentry;
-
-	if ((tabentry = find_tabstat_entry(relid)) == NULL)
-		result = 0;
-	else
-		result = (int64) (tabentry->counts.tuples_hot_updated);
-
-	PG_RETURN_INT64(result);
-}
-
-Datum
-pg_stat_get_xact_tuples_newpage_updated(PG_FUNCTION_ARGS)
-{
-	Oid			relid = PG_GETARG_OID(0);
-	int64		result;
-	PgStat_TableStatus *tabentry;
-
-	if ((tabentry = find_tabstat_entry(relid)) == NULL)
-		result = 0;
-	else
-		result = (int64) (tabentry->counts.tuples_newpage_updated);
-
-	PG_RETURN_INT64(result);
-}
-
-Datum
-pg_stat_get_xact_blocks_fetched(PG_FUNCTION_ARGS)
-{
-	Oid			relid = PG_GETARG_OID(0);
-	int64		result;
-	PgStat_TableStatus *tabentry;
-
-	if ((tabentry = find_tabstat_entry(relid)) == NULL)
-		result = 0;
-	else
-		result = (int64) (tabentry->counts.blocks_fetched);
-
-	PG_RETURN_INT64(result);
-}
-
-Datum
-pg_stat_get_xact_blocks_hit(PG_FUNCTION_ARGS)
-{
-	Oid			relid = PG_GETARG_OID(0);
-	int64		result;
-	PgStat_TableStatus *tabentry;
-
-	if ((tabentry = find_tabstat_entry(relid)) == NULL)
-		result = 0;
-	else
-		result = (int64) (tabentry->counts.blocks_hit);
-
-	PG_RETURN_INT64(result);
-}
-
 Datum
 pg_stat_get_xact_function_calls(PG_FUNCTION_ARGS)
 {