| From: | Magnus Hagander <magnus(at)hagander(dot)net> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Claudio Freire <klaussfreire(at)gmail(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Hot Standby Feedback should default to on in 9.3+ |
| Date: | 2012-12-01 00:11:10 |
| Message-ID: | CABUevEzD6iSzT1=oGemLRRWcGO6-hRYQuBTyEWgV-RZQgORD0A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Nov 30, 2012 at 10:09 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Claudio Freire <klaussfreire(at)gmail(dot)com> writes:
>> Without hot standby feedback, reporting queries are impossible. I've
>> experienced it. Cancellations make it impossible to finish any
>> decently complex reporting query.
>
> The original expectation was that slave-side cancels would be
> infrequent. Maybe there's some fixing/tuning to be done there.
It depends completely on the query pattern on the master. Saying that
cancellations makes it "impossible to finish any decently complex
reporting query" is completely incorrect - it depends on the queries
on the *master*, not on the complexity of the query on the slave. I
know a lot of scenarios where query cancels pretty much never happen
at all.
--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/
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