Add WAL data to backend statistics This commit adds per-backend WAL statistics, providing the same information as pg_stat_wal, except that it is now possible to know how much WAL activity is happening in each backend rather than an overall aggregate of all the activity. Like pg_stat_wal, the implementation relies on pgWalUsage, tracking the difference of activity between two reports to pgstats.
This data can be retrieved with a new system function called pg_stat_get_backend_wal(), that returns one tuple based on the PID provided in input. Like pg_stat_get_backend_io(), this is useful when joined with pg_stat_activity to get a live picture of the WAL generated for each running backend, showing how the activity is [un]balanced. pgstat_flush_backend() gains a new flag value, able to control the flush of the WAL stats. This commit relies mostly on the infrastructure provided by 9aea73fc61d4, that has introduced backend statistics. Bump catalog version. A bump of PGSTAT_FILE_FORMAT_ID is not required, as backend stats do not persist on disk. Author: Bertrand Drouvot <bertranddrouvot...@gmail.com> Reviewed-by: Michael Paquier <mich...@paquier.xyz> Reviewed-by: Nazir Bilal Yavuz <byavu...@gmail.com> Reviewed-by: Xuneng Zhou <xunengz...@gmail.com> Discussion: https://postgr.es/m/Z3zqc4o09dM/e...@ip-10-97-1-34.eu-west-3.compute.internal Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/76def4cdd7c2b32d19e950a160f834392ea51744 Modified Files -------------- doc/src/sgml/monitoring.sgml | 19 +++++++ src/backend/utils/activity/pgstat_backend.c | 87 ++++++++++++++++++++++++++++- src/backend/utils/activity/pgstat_wal.c | 1 + src/backend/utils/adt/pgstatfuncs.c | 26 ++++++++- src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.dat | 7 +++ src/include/pgstat.h | 41 ++++++++------ src/include/utils/pgstat_internal.h | 3 +- src/test/regress/expected/stats.out | 17 +++++- src/test/regress/sql/stats.sql | 9 ++- 10 files changed, 185 insertions(+), 27 deletions(-)
