mirror of
https://github.com/postgres/postgres.git
synced 2025-06-01 00:01:20 -04:00
9bacec15b6
Commit b4af70cb, which simplified state managed by VACUUM, performed refactoring of parallel VACUUM in passing. Confusion about the exact details of the tasks that the leader process is responsible for led to code that made it possible for parallel VACUUM to miss a subset of the table's indexes entirely. Specifically, indexes that fell under the min_parallel_index_scan_size size cutoff were missed. These indexes are supposed to be vacuumed by the leader (alongside any parallel unsafe indexes), but weren't vacuumed at all. Affected indexes could easily end up with duplicate heap TIDs, once heap TIDs were recycled for new heap tuples. This had generic symptoms that might be seen with almost any index corruption involving structural inconsistencies between an index and its table. To fix, make sure that the parallel VACUUM leader process performs any required index vacuuming for indexes that happen to be below the size cutoff. Also document the design of parallel VACUUM with these below-size-cutoff indexes. It's unclear how many users might be affected by this bug. There had to be at least three indexes on the table to hit the bug: a smaller index, plus at least two additional indexes that themselves exceed the size cutoff. Cases with just one additional index would not run into trouble, since the parallel VACUUM cost model requires two larger-than-cutoff indexes on the table to apply any parallel processing. Note also that autovacuum was not affected, since it never uses parallel processing. Test case based on tests from a larger patch to test parallel VACUUM by Masahiko Sawada. Many thanks to Kamigishi Rei for her invaluable help with tracking this problem down. Author: Peter Geoghegan <pg@bowt.ie> Author: Masahiko Sawada <sawada.mshk@gmail.com> Reported-By: Kamigishi Rei <iijima.yun@koumakan.jp> Reported-By: Andrew Gierth <andrew@tao11.riddles.org.uk> Diagnosed-By: Andres Freund <andres@anarazel.de> Bug: #17245 Discussion: https://postgr.es/m/17245-ddf06aaf85735f36@postgresql.org Discussion: https://postgr.es/m/20211030023740.qbnsl2xaoh2grq3d@alap3.anarazel.de Backpatch: 14-, where the refactoring commit appears.
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. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.