857340b026
When wal_compression=zstd, the compression of a full page image involves
ZSTD_compress(), that creates and destroys a zstd compression context
for each page processed.
Tests with FPI-heavy workloads have proven that this can be costly, and
a compression context can be reused across multiple pages. This commit
switches to use ZSTD_compressCCtx() for the compression of each page,
with ZSTD_CCtx allocated once in each backend, allocation happening the
first time it is required. If the allocation fails, the code
temporarily fails back to no compression, as a soft failure mode while
being inside a critical section.
Some tests have proved that this simple change can lead to a substantial
performance gain. For example, I have measured up to 6% faster runtime
and 8% less user CPU time for a VACUUM FULL generating WAL made mostly
of zstd-compressed FPIs.
ce3387b74b has done something similar for the decompression of pages
at replay.
Author: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
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.
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