From: pgsql-performance-owner@xxxxxxxxxxxxxx [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of Matheus de Oliveira
Sent: Thursday, January 10, 2013 2:12 PM
To: Heikki Linnakangas
Cc: pgsql-performance; Charles Gomes
Subject: Re: Partition insert trigger using C language
On Thu, Jan 10, 2013 at 4:54 PM, Heikki Linnakangas <hlinnakangas@xxxxxxxxxx> 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:
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
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
