a13cdbd3d8
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.
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/.