From: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Hadi Moshayedi <hadi(at)moshayedi(dot)net>, Kevin Grittner <kgrittn(at)ymail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, "mark(dot)kirkwood(at)catalyst(dot)net(dot)nz" <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> |
Subject: | Re: Improving avg performance for numeric |
Date: | 2013-03-20 11:02:59 |
Message-ID: | CAFj8pRCpkdU16yZByicA6jhwrv4kyqZVy-=oGanKg=FLg5OoSw@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Hello
2013/3/19 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> I wrote:
>> [ looks at patch... ] Oh, I see what's affecting the plan: you changed
>> the aggtranstypes to internal for a bunch of aggregates. That's not
>> very good, because right now the planner takes that to mean that the
>> aggregate could eat a lot of space. We don't want that to happen for
>> these aggregates, I think.
>
> After thinking about that for awhile: if we pursue this type of
> optimization, what would probably be appropriate is to add an aggregate
> property (stored in pg_aggregate) that allows direct specification of
> the size that the planner should assume for the aggregate's transition
> value. We were getting away with a hardwired assumption of 8K for
> "internal" because the existing aggregates that used that transtype all
> had similar properties, but it was always really a band-aid not a proper
> solution. A per-aggregate override could be useful in other cases too.
>
> This was looking like 9.4 material already, but adding such a property
> would definitely put it over the top of what we could think about
> squeezing into 9.3, IMO.
>
Postgres is not a "in memory" OLAP database, but lot of companies use
it for OLAP queries due pg comfortable usage. This feature can be very
interesting for these users - and can introduce interesting speedup
with relative low price.
Regards
Pavel
> regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Daniele Varrazzo | 2013-03-20 11:31:12 | A few string fixed |
Previous Message | Ants Aasma | 2013-03-20 11:01:28 | Re: Enabling Checksums |