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Index builds update pg_class.reltuples for the table. In parallel GIN builds, workers track the number of processed rows, and report it to the leader, who then updates the pg_class with a total. However, gin_parallel_build_main failed to initialize the bs_reltuples field, leaving it set to whatever happens to be on the stack (which may be bogus values like Infinity or NaN, or just impossibly high values). If such values get reported to the leader and stored in pg_class, that can have serious consequences. The pg_class.reltuples field is used to decide when a table is due for autovacuum or autoanalyze, and if it happens to be set to a bogus value, that may never happen. The field is also used by the optimizer when calculating costs. Fixed by initializing bs_reltuples together with the rest of the build state. The bs_numtuples was initialized later, but it seems cleaner to just initialize all the fields at once. After a bogus value gets persisted in pg_class, affected systems are unlikely to self-heal. That would require an ANALYZE, but preventing that is one of the consequences. We have considered forcing autoanalyze in these cases, but there's not a good way to reliably identify bogus values (except for a small minority like Infitiny/NaN). A manual ANALYZE on (possibly) affected tables is the only solution. Backpatch to 18, where parallel GIN builds were introduced. Reported-by: Jan Nidzwetzki <jan@planetscale.com> Discussion: https://postgr.es/m/518BA772-8026-412A-AA8F-A7FE4C6B3717@planetscale.com Backpatch-through: 18
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/18/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/18/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/.