Re: Partition insert trigger using C language

On Fri, Jan 11, 2013 at 8:19 AM, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com
> wrote:

> On 10.01.2013 21:48, Matheus de Oliveira wrote:
>
>> I have made a small modification to keep the plans, and it got from
>> 33957.768ms to 43782.376ms.
>>
>
> If I'm reading results.txt correctly, the avg runtimes are:
>
> C and SPI_execute_with_args: 58567.708 ms
> C and SPI_(prepare/keepplan/execute_**plan): 43782.376 ms
> C and heap_insert: 33957.768 ms
>
> So switching to prepared plans helped quite a lot, but it's still slower
> than direct heap_inserts.
>
>
Humm... You are right, I misread what it before, sorry. The 33957.768ms was
with heap_insert.

> One thing that caught my eye:
>
> CREATE OR REPLACE FUNCTION partition_insert_trigger_spi()
>> RETURNS trigger
>> LANGUAGE C
>> VOLATILE STRICT
>> AS 'partition_insert_trigger_spi'**,'partition_insert_trigger_**spi'
>> SET DateStyle TO 'ISO';
>>
>
> Calling a function with SET options has a fair amount of overhead, to
> set/restore the GUC on every invocation. That should be avoided in a
> performance critical function like this.
>
>
I (stupidly) used SPI_getvalue [1] and expected it to always return as
YYYY-MM-DD, but them I remembered it would do that only with DateStyle=ISO.

But the truth is that I couldn't see any overhead, because the function was
without that on my first tests, and after that I saw no difference on the
tests. I think I should use SPI_getbinvalue instead, but I don't know how
to parse the result to get year and month, any help on that?

[1]
https://github.com/matheusoliveira/pg_partitioning_tests/blob/master/src/spi/partition_insert_trigger_spi.c#L103

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