70d8a91f82
ca307d5cec introduced keeping WAL segments by slot's last saved restart LSN.
It also added an assertion that the slot's restart LSN never goes backward.
However, situations when the restart LSN goes backward have been spotted by
buildfarm animals and investigated in the thread.
When pg_receivewal starts the replication, it sets the last replayed LSN to
the beginning of the segment, which is older than what
ReplicationSlotReserveWal() set for the slot. A similar situation can happen
to pg_basebackup. When standby reconnects to the primary, it sends the last
replayed LSN, which might be older than the last confirmed flush LSN. In
both these situations, a concurrent checkpoint may trigger an assert trap.
Based on ideas from Vitaly Davydov <v.davydov@postgrespro.ru>,
Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>,
Vignesh C <vignesh21@gmail.com>,
Amit Kapila <amit.kapila16@gmail.com>.
Reported-by: Vignesh C <vignesh21@gmail.com>
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CALDaNm3s-jpQTe1MshsvQ8GO%3DTLj233JCdkQ7uZ6pwqRVpxAdw%40mail.gmail.com
Reviewed-by: Vignesh C <vignesh21@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.