Re: Partition insert trigger using C language

On Thu, Jan 10, 2013 at 5:51 PM, Charles Gomes <
charles(dot)gomes(at)benchmarksolutions(dot)com> wrote:

> ** **
>
> *From:* pgsql-performance-owner(at)postgresql(dot)org [mailto:
> pgsql-performance-owner(at)postgresql(dot)org] *On Behalf Of *Matheus de Oliveira
> *Sent:* Thursday, January 10, 2013 2:12 PM
> *To:* Heikki Linnakangas
> *Cc:* pgsql-performance; Charles Gomes
> *Subject:* Re: [PERFORM] Partition insert trigger using C language****
>
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>
> ** **
>
> On Thu, Jan 10, 2013 at 4:54 PM, Heikki Linnakangas <
> hlinnakangas(at)vmware(dot)com> wrote:****
>
>> On 10.01.2013 20:45, Matheus de Oliveira wrote:
>>
>> Inspired by Charles' thread and the work of Emmanuel [1], I have made some
>> experiments trying to create a trigger to make partitioning using C
>> language.
>>
>> The first attempt was not good, I tried to use SPI [2] to create a query
>> to
>> insert into the correct child table, but it took almost no improvement
>> compared with the PL/pgSQL code.
>>
>>
>>
>> The right way to do this with SPI is to prepare each insert-statement on
>> first invocation (SPI_prepare + SPI_keepplan), and reuse the plan after
>> that (SPI_execute_with_args).
>>
>> If you construct and plan the query on every invocation, it's not
>> surprising that it's no different from PL/pgSQL performance.
>>
>>
>> Yeah. I thought about that, but the problem was that I assumed the
>> INSERTs came with random date, so in the worst scenario I would have to
>> keep the plans of all of the child partitions. Am I wrong?
>>
>> But thinking better, even with hundreds of partitions, it wouldn't use to
>> much memory/resource, would it?
>>
>> In fact, I didn't give to much attention to SPI method, because the other
>> one is where we can have more fun, =P.
>>
>> Anyway, I'll change the code (maybe now), and see if it gets closer to
>> the other method (that uses heap_insert), and will post back the results
>> here.
>>
>
>>
>
>
****
>
> Interesting that you got an improvement. In my case I get almost no
> improvement at all:****
>
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>
> PL/SQL – Dynamic Trigger****
>
> 4:15:54****
>
> PL/SQL - CASE / WHEN Statements****
>
> 4:12:29****
>
> PL/SQL - IF Statements****
>
> 4:12:39****
>
> C Trigger****
>
> 4:10:49****
>
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>
> Here is my code, I’m using heap insert and updating the indexes. With a
> similar approach of yours.****
>
> The trigger is aware of ****
>
> http://www.charlesrg.com/~charles/pgsql/partition2.c****
>
> **
>

Humm... Looking at your code, I saw no big difference from mine. The only
thing I saw is that you don't fire triggers, but it would be even faster
this way. Another thing that could cause that is the number of partitions,
I tried only with 12.

Could you make a test suite? Or try to run with my function in your
scenario? It would be easy to make it get the partitions by day [1].

[1] https://gist.github.com/4509782

Regards,
--
Matheus de Oliveira
Analista de Banco de Dados
Dextra Sistemas - MPS.Br nível F!
www.dextra.com.br/postgres