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REINDEX CONCURRENTLY run on a toast index or a toast relation could corrupt the target indexes rebuilt, as a backend running in parallel that manipulates toast values would directly release the lock on the toast relation when its local operation is done, rather than releasing the lock once the transaction that manipulated the toast values committed. The fix done here is simple: we now hold a ROW EXCLUSIVE lock on the toast relation when saving or deleting a toast value until the transaction working on them is committed, so as a concurrent reindex happening in parallel would be able to wait for any activity and see any new rows inserted (or deleted). An isolation test is added to check after the case fixed here, which is a bit fancy by design as it relies on allow_system_table_mods to rename the toast table and its index to fixed names. This way, it is possible to reindex them directly without any dependency on the OID of the underlying relation. Note that this could not use a DO block either, as REINDEX CONCURRENTLY cannot be run in a transaction block. The test is backpatched down to 13, where it is possible, thanks to c4a7a39, to use allow_system_table_mods in a test suite. Reported-by: Alexey Ermakov Analyzed-by: Andres Freund, Noah Misch Author: Michael Paquier Reviewed-by: Nathan Bossart Discussion: https://postgr.es/m/17268-d2fb426e0895abd4@postgresql.org Backpatch-through: 12
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/.