| From: | Magnus Hagander <magnus(at)hagander(dot)net> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Michael Banck <michael(dot)banck(at)credativ(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
| Subject: | Re: Online enabling of checksums |
| Date: | 2018-03-27 06:56:10 |
| Message-ID: | CABUevEyRsAUOTVqQ8PvCAOHd+0foKTwRq34QD3LuGVLa0ydHLg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Mar 26, 2018 at 10:09 PM, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com
> wrote:
> Hi,
>
> I see enable_data_checksums() does this:
>
> if (cost_limit <= 0)
> ereport(ERROR,
> (errmsg("cost limit must be a positive value")));
>
> Is there a reason not to allow -1 (no limit), just like for vacuum_cost?
>
>
Eh. vaccum_cost_limit cannot be set to -1 (1 is the lowest). Neither can
vacuum_cost_delay -- it is set to *0* to disable it (which is how the
cost_delay parameter is handled here as well).
Are you thinking autovacuum_vacuum_cost_limit where -1 means "use
vacuum_cost_limit"?
The reason to disallow cost_limit=0 is to avoid divide-by-zero. We could
allow -1 and have it mean "use vacuum_cost_limit", but I'm not sure how
relevant that really would be in this context?
--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>
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