Re: Partition insert trigger using C language

On 11.01.2013 12:36, Matheus de Oliveira wrote:

On Fri, Jan 11, 2013 at 8:19 AM, Heikki Linnakangas<hlinnakangas@vmware.com

wrote:

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.

Oh, ok then. I would've expected it to make a measurable difference.

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?

The fastest way is probably to use j2date like date_out does:

  DateADT               date = DatumGetDateADT(x)
  int year, month, mday;

  if (DATE_NOT_FINITE(date))
        elog(ERROR, "date must be finite");
  j2date(date + POSTGRES_EPOCH_JDATE, &year, &month, &mday);

- Heikki