Re: pglz performance

From: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Vladimir Leskov <vladimirlesk(at)yandex-team(dot)ru>
Subject: Re: pglz performance
Date: 2019-06-27 18:33:16
Message-ID: 169163A8-C96F-4DBE-A062-7D1CECBE9E5D@yandex-team.ru
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> 13 мая 2019 г., в 12:14, Michael Paquier <michael(at)paquier(dot)xyz> написал(а):
>
> Decompression can matter a lot for mostly-read workloads and
> compression can become a bottleneck for heavy-insert loads, so
> improving compression or decompression should be two separate
> problems, not two problems linked. Any improvement in one or the
> other, or even both, is nice to have.

Here's patch hacked by Vladimir for compression.

Key differences (as far as I see, maybe Vladimir will post more complete list of optimizations):
1. Use functions instead of macro-functions: not surprisingly it's easier to optimize them and provide less constraints for compiler to optimize.
2. More compact hash table: use indexes instead of pointers.
3. More robust segment comparison: like memcmp, but return index of first different byte

In weighted mix of different data (same as for compression), overall speedup is x1.43 on my machine.

Current implementation is integrated into test_pglz suit for benchmarking purposes[0].

Best regards, Andrey Borodin.

[0] https://github.com/x4m/test_pglz

Attachment Content-Type Size
0001-Reorganize-pglz-compression-code.patch application/octet-stream 24.2 KB

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