diff options
| author | Peter Geoghegan <pg@bowt.ie> | 2023-03-23 11:16:17 -0700 |
|---|---|---|
| committer | Peter Geoghegan <pg@bowt.ie> | 2023-03-23 11:16:17 -0700 |
| commit | ae4fdde1352fa6b2c9123e91435efafc78c370a0 (patch) | |
| tree | 2f0bc32e55b16114a24d14180231a117be526e8b /doc/src | |
| parent | 3b50275b12950280fb07193e24a4f400ed8a9fef (diff) | |
Count updates that move row to a new page.
Add pgstat counter to track row updates that result in the successor
version going to a new heap page, leaving behind an original version
whose t_ctid points to the new version. The current count is shown by
the n_tup_newpage_upd column of each of the pg_stat_*_tables views.
The new n_tup_newpage_upd column complements the existing n_tup_hot_upd
and n_tup_upd columns. Tables that have high n_tup_newpage_upd values
(relative to n_tup_upd) are good candidates for tuning heap fillfactor.
Corey Huinker, with small tweaks by me.
Author: Corey Huinker <corey.huinker@gmail.com>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CADkLM=ded21M9iZ36hHm-vj2rE2d=zcKpUQMds__Xm2pxLfHKA@mail.gmail.com
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/monitoring.sgml | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 7ab4424bf13..21e6ce2841e 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -4789,7 +4789,7 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i <structfield>n_tup_ins</structfield> <type>bigint</type> </para> <para> - Number of rows inserted + Total number of rows inserted </para></entry> </row> @@ -4798,7 +4798,10 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i <structfield>n_tup_upd</structfield> <type>bigint</type> </para> <para> - Number of rows updated (includes <link linkend="storage-hot">HOT updated rows</link>) + Total number of rows updated. (This includes row updates + counted in <structfield>n_tup_hot_upd</structfield> and + <structfield>n_tup_newpage_upd</structfield>, and remaining + non-<acronym>HOT</acronym> updates.) </para></entry> </row> @@ -4807,7 +4810,7 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i <structfield>n_tup_del</structfield> <type>bigint</type> </para> <para> - Number of rows deleted + Total number of rows deleted </para></entry> </row> @@ -4816,8 +4819,23 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i <structfield>n_tup_hot_upd</structfield> <type>bigint</type> </para> <para> - Number of rows HOT updated (i.e., with no separate index - update required) + Number of rows <link linkend="storage-hot">HOT updated</link>. + These are updates where no successor versions are required in + indexes. + </para></entry> + </row> + + <row> + <entry role="catalog_table_entry"><para role="column_definition"> + <structfield>n_tup_newpage_upd</structfield> <type>bigint</type> + </para> + <para> + Number of rows updated where the successor version goes onto a + <emphasis>new</emphasis> heap page, leaving behind an original + version with a + <link linkend="storage-tuple-layout"><structfield>t_ctid</structfield> + field</link> that points to a different heap page. These are + always non-<acronym>HOT</acronym> updates. </para></entry> </row> |