From: | Condor <condor(at)stz-bg(dot)com> |
---|---|
To: | <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Problem with reading data from standby server ? |
Date: | 2012-04-21 15:38:57 |
Message-ID: | c69174615613525decf74d87a4332406@stz-bg.com |
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Thread: | |
Lists: | pgsql-general |
On 21.04.2012 12:59, Andres Freund wrote:
> On Friday, April 20, 2012 10:39:25 AM Condor wrote:
>> array_accumulate aggregate is:
>>
>>
>> CREATE AGGREGATE array_accumulate (
>> sfunc = array_append,
>> basetype = anyelement,
>> stype = anyarray,
>> initcond = '{}'
>> );
> Btw, if you replace that by array_agg which is builtin in any version
> support
> HS/SR the whole query might finish faster and thus is less likely to
> cause
> conflicts.
No, the speed is the same, I just check with explain but yes, I will
switch to use array_agg
>
> If youre already on 9.1 you might also want to look into
> hot_standby_feedback
> that can also reduce the likelihood of conflicts by informing the
> master what
> is going on on the standby.
>
This option hot_standby_feedback look interesting, but when I read what
do more questions coming like:
This can cause database bloat on the primary for some workloads. Well
if I run one query every hour and take
30 min to finish the job, with how much my database on primary will be
increase and when I run vaccumdb on master do this
blob will gone. Well I watch one treat here, one guy with 540 gb
database with huge blob and Im little scared do I
will have the same result. Also if something happened on the master
server and it's going down do I will have all
wal files in archive directory on standby server and did postgres will
apply them auto after finish the query or
I need to do this manually.
> Greetings,
>
> Andres
Greetings,
Condor
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