ce3387b74b
Restoring each zstd-compressed full-page image currently creates and destroys a decompression context. One decompression context gets now saved in a XLogReaderState on first use, reused for the decompression of any follow-up zstd-compressed pages. The decompression context is freed in XLogReaderFree(). In non-FRONTEND builds, a memory context reset callback is registered to make sure that the decompression context does not leak. Note that zstd has APIs to either initialize a pre-allocated decompression context or assign custom allocation and free routines, but none of these are available for builds that dynamically link to the zstd library (ZSTDLIB_STATIC_API). Tomas Vondra has done some benchmarking showing that for a FPI-heavy set of WAL records, reusing the decompression context can nicely improve the recovery time, bringing it close to lz4. In my own measurements, I have seen up to a 4% faster recovery time when replaying records made mostly of zstd-compressed full-page images between HEAD and this improvement. Andrey has seen better numbers than that. Author: Andrey Borodin <x4mmm@yandex-team.ru> Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://www.postgresql.org/message-id/asRsOl73nf8GeBFd@paquier.xyz
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/.