From: | Magnus Hagander <magnus(at)hagander(dot)net> |
---|---|
To: | Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> |
Cc: | Josh Berkus <josh(at)agliodbs(dot)com>, postgres hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: max_wal_senders must die |
Date: | 2010-10-19 11:18:07 |
Message-ID: | AANLkTi=hGC4UpNetGxndYfsDsaMcvefrAC+y9CXUOJ=n@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Oct 19, 2010 at 13:14, Stefan Kaltenbrunner
<stefan(at)kaltenbrunner(dot)cc> wrote:
> Josh Berkus wrote:
>>
>> Hackers,
>>
>> What purpose is served, exactly, by max_wal_senders?
>>
>> In order for a standby to connect, it must have a superuser login, and
>> replication connections must be enabled in pg_hba.conf. How is having one
>> more setting in one more file you have to enable on the master benefitting
>> anyone?
>>
>> Under what bizarre set of circumstances would anyone have runaway
>> connections from replicas to the master?
>>
>> Proposed that we simply remove this setting in 9.1. The real maximum wal
>> senders should be whatever max_connections is.
>
> I disagree - limiting the maximum number of replication connections is
> important for my usecases.
> Replication connections are significantly more heavilyweight than a normal
> connection and right now I for example simply use this setting to prevent
> stupid mistakes (especially in virtualized^cloudstyle environments).
>
> What we really should look into is using a less privileged role - or
> dedicated replication role - and use the existing per role connection limit
> feature. That feature is unlimited by default, people can change it like
> for every role and we can git rid of that guc.
+1 for being able to control it that wya - that should keep it simple
for the newbie usecase, while retaining the ability for fine-grained
control for those who need it.
I think it's already on the TODO for 9.1 to use a separate role for it...
If we want something fixed *now*, should we perhaps just bump the
*default* value for max_wal_senders to 5 or something?
--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/
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