diff --git a/src/backend/utils/activity/pgstat_io.c b/src/backend/utils/activity/pgstat_io.c
index 0e07e0848d3..c4199d18c8a 100644
--- a/src/backend/utils/activity/pgstat_io.c
+++ b/src/backend/utils/activity/pgstat_io.c
@@ -36,18 +36,16 @@ pgstat_bktype_io_stats_valid(PgStat_BktypeIO *backend_io,
 {
 	bool		bktype_tracked = pgstat_tracks_io_bktype(bktype);
 
-	for (IOObject io_object = IOOBJECT_FIRST;
-		 io_object < IOOBJECT_NUM_TYPES; io_object++)
+	for (int io_object = 0; io_object < IOOBJECT_NUM_TYPES; io_object++)
 	{
-		for (IOContext io_context = IOCONTEXT_FIRST;
-			 io_context < IOCONTEXT_NUM_TYPES; io_context++)
+		for (int io_context = 0; io_context < IOCONTEXT_NUM_TYPES; io_context++)
 		{
 			/*
 			 * Don't bother trying to skip to the next loop iteration if
 			 * pgstat_tracks_io_object() would return false here. We still
 			 * need to validate that each counter is zero anyway.
 			 */
-			for (IOOp io_op = IOOP_FIRST; io_op < IOOP_NUM_TYPES; io_op++)
+			for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
 			{
 				/* No stats, so nothing to validate */
 				if (backend_io->data[io_object][io_context][io_op] == 0)
@@ -111,14 +109,11 @@ pgstat_flush_io(bool nowait)
 	else if (!LWLockConditionalAcquire(bktype_lock, LW_EXCLUSIVE))
 		return true;
 
-	for (IOObject io_object = IOOBJECT_FIRST;
-		 io_object < IOOBJECT_NUM_TYPES; io_object++)
+	for (int io_object = 0; io_object < IOOBJECT_NUM_TYPES; io_object++)
 	{
-		for (IOContext io_context = IOCONTEXT_FIRST;
-			 io_context < IOCONTEXT_NUM_TYPES; io_context++)
+		for (int io_context = 0; io_context < IOCONTEXT_NUM_TYPES; io_context++)
 		{
-			for (IOOp io_op = IOOP_FIRST;
-				 io_op < IOOP_NUM_TYPES; io_op++)
+			for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
 				bktype_shstats->data[io_object][io_context][io_op] +=
 					PendingIOStats.data[io_object][io_context][io_op];
 		}
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9d707c35216..b61a12382b3 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1306,7 +1306,7 @@ pg_stat_get_io(PG_FUNCTION_ARGS)
 
 	reset_time = TimestampTzGetDatum(backends_io_stats->stat_reset_timestamp);
 
-	for (BackendType bktype = B_INVALID; bktype < BACKEND_NUM_TYPES; bktype++)
+	for (int bktype = 0; bktype < BACKEND_NUM_TYPES; bktype++)
 	{
 		Datum		bktype_desc = CStringGetTextDatum(GetBackendTypeDesc(bktype));
 		PgStat_BktypeIO *bktype_stats = &backends_io_stats->stats[bktype];
@@ -1325,13 +1325,11 @@ pg_stat_get_io(PG_FUNCTION_ARGS)
 		if (!pgstat_tracks_io_bktype(bktype))
 			continue;
 
-		for (IOObject io_obj = IOOBJECT_FIRST;
-			 io_obj < IOOBJECT_NUM_TYPES; io_obj++)
+		for (int io_obj = 0; io_obj < IOOBJECT_NUM_TYPES; io_obj++)
 		{
 			const char *obj_name = pgstat_get_io_object_name(io_obj);
 
-			for (IOContext io_context = IOCONTEXT_FIRST;
-				 io_context < IOCONTEXT_NUM_TYPES; io_context++)
+			for (int io_context = 0; io_context < IOCONTEXT_NUM_TYPES; io_context++)
 			{
 				const char *context_name = pgstat_get_io_context_name(io_context);
 
@@ -1359,7 +1357,7 @@ pg_stat_get_io(PG_FUNCTION_ARGS)
 				 */
 				values[IO_COL_CONVERSION] = Int64GetDatum(BLCKSZ);
 
-				for (IOOp io_op = IOOP_FIRST; io_op < IOOP_NUM_TYPES; io_op++)
+				for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
 				{
 					int			col_idx = pgstat_get_io_op_index(io_op);
 
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index db9675884f3..f43fac09ede 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -287,7 +287,6 @@ typedef enum IOObject
 	IOOBJECT_TEMP_RELATION,
 } IOObject;
 
-#define IOOBJECT_FIRST IOOBJECT_RELATION
 #define IOOBJECT_NUM_TYPES (IOOBJECT_TEMP_RELATION + 1)
 
 typedef enum IOContext
@@ -298,7 +297,6 @@ typedef enum IOContext
 	IOCONTEXT_VACUUM,
 } IOContext;
 
-#define IOCONTEXT_FIRST IOCONTEXT_BULKREAD
 #define IOCONTEXT_NUM_TYPES (IOCONTEXT_VACUUM + 1)
 
 typedef enum IOOp
@@ -311,7 +309,6 @@ typedef enum IOOp
 	IOOP_WRITE,
 } IOOp;
 
-#define IOOP_FIRST IOOP_EVICT
 #define IOOP_NUM_TYPES (IOOP_WRITE + 1)
 
 typedef struct PgStat_BktypeIO