mirror of
https://github.com/postgres/postgres.git
synced 2026-03-21 18:10:25 -04:00
ff99918c62
This commit adds new GUC track_wal_io_timing. When this is enabled, the total amounts of time XLogWrite writes and issue_xlog_fsync syncs WAL data to disk are counted in pg_stat_wal. This information would be useful to check how much WAL write and sync affect the performance. Enabling track_wal_io_timing will make the server query the operating system for the current time every time WAL is written or synced, which may cause significant overhead on some platforms. To avoid such additional overhead in the server with track_io_timing enabled, this commit introduces track_wal_io_timing as a separate parameter from track_io_timing. Note that WAL write and sync activity by walreceiver has not been tracked yet. This commit makes the server also track the numbers of times XLogWrite writes and issue_xlog_fsync syncs WAL data to disk, in pg_stat_wal, regardless of the setting of track_wal_io_timing. This counters can be used to calculate the WAL write and sync time per request, for example. Bump PGSTAT_FILE_FORMAT_ID. Bump catalog version. Author: Masahiro Ikeda Reviewed-By: Japin Li, Hayato Kuroda, Masahiko Sawada, David Johnston, Fujii Masao Discussion: https://postgr.es/m/0509ad67b585a5b86a83d445dfa75392@oss.nttdata.com
58 lines
2.5 KiB
C
58 lines
2.5 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* catversion.h
|
|
* "Catalog version number" for PostgreSQL.
|
|
*
|
|
* The catalog version number is used to flag incompatible changes in
|
|
* the PostgreSQL system catalogs. Whenever anyone changes the format of
|
|
* a system catalog relation, or adds, deletes, or modifies standard
|
|
* catalog entries in such a way that an updated backend wouldn't work
|
|
* with an old database (or vice versa), the catalog version number
|
|
* should be changed. The version number stored in pg_control by initdb
|
|
* is checked against the version number compiled into the backend at
|
|
* startup time, so that a backend can refuse to run in an incompatible
|
|
* database.
|
|
*
|
|
* The point of this feature is to provide a finer grain of compatibility
|
|
* checking than is possible from looking at the major version number
|
|
* stored in PG_VERSION. It shouldn't matter to end users, but during
|
|
* development cycles we usually make quite a few incompatible changes
|
|
* to the contents of the system catalogs, and we don't want to bump the
|
|
* major version number for each one. What we can do instead is bump
|
|
* this internal version number. This should save some grief for
|
|
* developers who might otherwise waste time tracking down "bugs" that
|
|
* are really just code-vs-database incompatibilities.
|
|
*
|
|
* The rule for developers is: if you commit a change that requires
|
|
* an initdb, you should update the catalog version number (as well as
|
|
* notifying the pgsql-hackers mailing list, which has been the
|
|
* informal practice for a long time).
|
|
*
|
|
* The catalog version number is placed here since modifying files in
|
|
* include/catalog is the most common kind of initdb-forcing change.
|
|
* But it could be used to protect any kind of incompatible change in
|
|
* database contents or layout, such as altering tuple headers.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/catalog/catversion.h
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#ifndef CATVERSION_H
|
|
#define CATVERSION_H
|
|
|
|
/*
|
|
* We could use anything we wanted for version numbers, but I recommend
|
|
* following the "YYYYMMDDN" style often used for DNS zone serial numbers.
|
|
* YYYYMMDD are the date of the change, and N is the number of the change
|
|
* on that day. (Hopefully we'll never commit ten independent sets of
|
|
* catalog changes on the same day...)
|
|
*/
|
|
|
|
/* yyyymmddN */
|
|
#define CATALOG_VERSION_NO 202103093
|
|
|
|
#endif
|