Re: Improving avg performance for numeric

2013/3/19 Kevin Grittner <kgrittn(at)ymail(dot)com>:
> Hadi Moshayedi <hadi(at)moshayedi(dot)net> wrote:
>
>> I updated the patch by taking ideas from your patch, and unifying
>> the transition struct and update function for different
>> aggregates. The speed of avg improved even more. It now has 60%
>> better performance than the current committed version.
>
> Outstanding!

I did some tests ala OLAP queries and I am thinking so ~ 40% speedup
for queries with AVG is realistic. Depends on other conditions.

But there are lot of situation when data are in shared buffers or file
system memory and then this patch can carry significant speedup - and
probably can be better if some better algorithm for sum two numeric
numbers in aggregate.

Regards

Pavel

>
>> I also noticed that this patch makes matview test fail. It seems
>> that it just changes the ordering of rows for queries like
>> "SELECT * FROM tv;". Does this seem like a bug in my patch, or
>> should we add "ORDER BY" clauses to this test to make it more
>> deterministic?
>
> I added some ORDER BY clauses. That is probably a good thing
> anyway for purposes of code coverage. Does that fix it for you?
>
> --
> Kevin Grittner
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company