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Handle logical slot conflicts on standby

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During WAL replay on the standby, when a conflict with a logical slot is
identified, invalidate such slots. There are two sources of conflicts:
1) Using the information added in 6af1793954, logical slots are invalidated if
   required rows are removed
2) wal_level on the primary server is reduced to below logical

Uses the infrastructure introduced in the prior commit. FIXME: add commit
reference.

Change InvalidatePossiblyObsoleteSlot() to use a recovery conflict to
interrupt use of a slot, if called in the startup process. The new recovery
conflict is added to pg_stat_database_conflicts, as confl_active_logicalslot.

See 6af1793954 for an overall design of logical decoding on a standby.

Bumps catversion for the addition of the pg_stat_database_conflicts column.
Bumps PGSTAT_FILE_FORMAT_ID for the same reason.

Author: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Author: Amit Khandekar <amitdkhan.pg@gmail.com> (in an older version)
Reviewed-by: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Fabrízio de Royes Mello <fabriziomello@gmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/20230407075009.igg7be27ha2htkbt@awork3.anarazel.de
This commit is contained in:
Andres Freund
2023-04-07 23:11:28 -07:00
parent be87200efd
commit 26669757b6
20 changed files with 95 additions and 6 deletions
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11
doc/src/sgml/monitoring.sgml
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@ -4742,6 +4742,17 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
deadlocks
</para></entry>
</row>
<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>confl_active_logicalslot</structfield> <type>bigint</type>
</para>
<para>
Number of uses of logical slots in this database that have been
canceled due to old snapshots or a too low <xref linkend="guc-wal-level"/>
on the primary
</para></entry>
</row>
</tbody>
</tgroup>
</table>