3f968b9415
It incorrectly used GetBufferDescriptor instead of GetLocalBufferDescriptor, causing it to not find the correct buffer in most cases, and performing an out-of-bounds memory read in the corner case that temp_buffers > shared_buffers. It also bumped the usage-count on the buffer, even if it was previously pinned. That won't lead to crashes or incorrect results, but it's different from what the shared-buffer case does, and different from the usual code in LocalBufferAlloc. Fix that too, and make the code ordering match LocalBufferAlloc() more closely, so that it's easier to verify that it's doing the same thing. Currently, ReadRecentBuffer() is only used with non-temp relations, in WAL redo, so the broken code is currently dead code. However, it could be used by extensions. Backpatch-through: 14 Discussion: https://www.postgresql.org/message-id/2d74b46f-27c9-fb31-7f99-327a87184cc0%40iki.fi Reviewed-by: Thomas Munro, Zhang Mingli, Richard Guo
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/.