83c39a1f7f
If vacuum fails to remove a tuple with xmax older than VacuumCutoffs->OldestXmin and younger than GlobalVisState->maybe_needed, it may attempt to freeze the tuple's xmax and then ERROR out in pre-freeze checks with "cannot freeze committed xmax". Fix this by having vacuum always remove tuples older than OldestXmin. It is possible for GlobalVisState->maybe_needed to precede OldestXmin if maybe_needed is forced to go backward while vacuum is running. This can happen if a disconnected standby with a running transaction older than VacuumCutoffs->OldestXmin reconnects to the primary after vacuum initially calculates GlobalVisState and OldestXmin. In back branches starting with 14, the first version using GlobalVisState, failing to remove tuples older than OldestXmin during pruning caused vacuum to infinitely loop in lazy_scan_prune(), as investigated on this [1] thread. After 1ccc1e05ae removed the retry loop in lazy_scan_prune() and stopped comparing tuples to OldestXmin, the hang could no longer happen, but we could still attempt to freeze dead tuples with xmax older than OldestXmin -- resulting in an ERROR. Fix this by always removing dead tuples with xmax older than VacuumCutoffs->OldestXmin. This is okay because the standby won't replay the tuple removal until the tuple is removable. Thus, the worst that can happen is a recovery conflict. [1] https://postgr.es/m/20240415173913.4zyyrwaftujxthf2%40awork3.anarazel.de#1b216b7768b5bd577a3d3d51bd5aadee Back-patch through 14 Author: Melanie Plageman Reviewed-by: Peter Geoghegan, Robert Haas, Andres Freund, Heikki Linnakangas, and Noah Misch Discussion: https://postgr.es/m/CAAKRu_bDD7oq9ZwB2OJqub5BovMG6UjEYsoK2LVttadjEqyRGg%40mail.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/.