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Add wal_fpi_bytes to pg_stat_wal and pg_stat_get_backend_wal()

This new counter, called "wal_fpi_bytes", tracks the total amount in
bytes of full page images (FPIs) generated in WAL.  This data becomes
available globally via pg_stat_wal, and for backend statistics via
pg_stat_get_backend_wal().

Previously, this information could only be retrieved with pg_waldump or
pg_walinspect, which may not be available depending on the environment,
and are expensive to execute.  It offers hints about how much FPIs
impact the WAL generated, which could be a large percentage for some
workloads, as well as the effects of wal_compression or page holes.

Bump catalog version.
Bump PGSTAT_FILE_FORMAT_ID, due to the addition of wal_fpi_bytes in
PgStat_WalCounters.

Author: Shinya Kato <shinya11.kato@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAOzEurQtZEAfg6P0kU3Wa-f9BWQOi0RzJEMPN56wNTOmJLmfaQ@mail.gmail.com
This commit is contained in:
Michael Paquier
2025-10-28 16:21:51 +09:00
parent 3e8e05596a
commit f9a09aa295
12 changed files with 46 additions and 15 deletions

View File

@@ -2306,9 +2306,10 @@ pg_stat_user_tables| SELECT relid,
pg_stat_wal| SELECT wal_records,
wal_fpi,
wal_bytes,
wal_fpi_bytes,
wal_buffers_full,
stats_reset
FROM pg_stat_get_wal() w(wal_records, wal_fpi, wal_bytes, wal_buffers_full, stats_reset);
FROM pg_stat_get_wal() w(wal_records, wal_fpi, wal_bytes, wal_fpi_bytes, wal_buffers_full, stats_reset);
pg_stat_wal_receiver| SELECT pid,
status,
receive_start_lsn,