| From: | Petr Jelinek <petr(at)2ndquadrant(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Andrey Borodin <x4mmm(at)yandex-team(dot)ru>, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>, Michael Paquier <michael(at)paquier(dot)xyz>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Vladimir Leskov <vladimirlesk(at)yandex-team(dot)ru> |
| Subject: | Re: pglz performance |
| Date: | 2019-08-04 22:19:28 |
| Message-ID: | dc736f7e-7b32-cb41-853c-0b0c46bef9f3@2ndquadrant.com |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 05/08/2019 00:15, Andres Freund wrote:
> Hi,
>
> On 2019-08-04 17:53:26 +0200, Petr Jelinek wrote:
>>> 5) I wonder why compression_algorithm is defined as PGC_SIGHUP. Why not
>>> to allow users to set it per session? I suppose we might have a separate
>>> option for WAL compression_algorithm.
>>>
>>
>> Yeah I was thinking we might want to change wal_compression to enum as well.
>> Although that complicates the code quite a bit (the caller has to decide
>> algorithm instead compression system doing it).
>
> Isn't that basically required anyway? The WAL record will need to carry
> information about the type of compression used, independent of
> PGC_SIGHUP/PGC_USERSET, unless you want to make it an initdb option or
> something super heavyweight like that.
>
It carries that information inside the compressed value, like I said in
the other reply, that's why the extra byte.
--
Petr Jelinek
2ndQuadrant - PostgreSQL Solutions for the Enterprise
https://www.2ndQuadrant.com/
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