0ebeec35fc
ProcArrayInstallImportedXmin verifies that the source transaction (the transaction whose snapshot we're importing) is still running, and then installs the caller's imported xmin. These steps have to be atomic. But it was just about possible for VACUUM to fail to observe the imported xmin in either the source proc or the importing one. This could result in VACUUM pruning away deleted tuples that were still visible to the imported snapshot. To fix, take ProcArrayLock in exclusive mode while importing an exported snapshot's xmin within ProcArrayInstallImportedXmin. That guarantees that a concurrent VACUUM's OldestXmin cannot advance past the xmin (one proc or the other always advertises an xmin that holds it back). Author: Chee Wooson <chee.wooson@gmail.com> Reviewed-by: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/20260730042128.714201-1-chee.wooson@gmail.com Backpatch-through: 14
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/.