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dd1634ddbd
ginVacuumPostingTreeLeaves swaps a shared buffer lock for an exclusive
one when it encounters a leaf page. It neglected to re-verify whether a
page that was initially a leaf root page became an internal page due to
a concurrent root page split (during the window when no lock was held).
It was therefore possible for GIN VACUUM to spuriously treat an internal
page as a leaf page, leading to data corruption. VACUUM could miss dead
TIDs that it was required to remove, leaving behind dangling references
in the index.
To fix, re-verify that a leaf page is still a leaf page after an
exclusive lock is acquired. If it isn't, drop our exclusive lock and
acquire a shared lock so that the non-leaf root page gets processed in
the usual way.
Oversight in commit fd83c83d, which fixed a deadlock bug in GIN posting
tree vacuuming.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CAH2-Wz=RBpJTQgvOxr6C=J04dExmFSt1E3F-r+cRTQ56hEotkg@mail.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. 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/.