Remove buffers_backend and buffers_backend_fsync from pg_stat_checkpointer

Two attributes related to checkpointer statistics are removed in this
commit:
- buffers_backend, that counts the number of buffers written directly by
a backend.
- buffers_backend_fsync, that counts the number of times a backend had
to do fsync() by its own.

These are actually not checkpointer properties but backend properties.
Also, pg_stat_io provides a more accurate and equivalent report of these
numbers, by tracking all the I/O stats related to backends, including
writes and fsyncs, so storing them in pg_stat_checkpointer was
redundant.

Thanks also to Robert Haas and Amit Kapila for their input.

Bump catalog version.

Author: Bharath Rupireddy
Reviewed-by: Bertrand Drouvot, Andres Freund
Discussion: https://postgr.es/m/20230210004604.mcszbscsqs3bc5nx@awork3.anarazel.de

1 files changed, 0 insertions, 2 deletions

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index fe2642f71a4..e6fd20f1ce2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -265,8 +265,6 @@ typedef struct PgStat_CheckpointerStats
 	PgStat_Counter checkpoint_write_time;	/* times in milliseconds */
 	PgStat_Counter checkpoint_sync_time;
 	PgStat_Counter buf_written_checkpoints;
-	PgStat_Counter buf_written_backend;
-	PgStat_Counter buf_fsync_backend;
 } PgStat_CheckpointerStats;