Hi All,
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.
Then, I used the Emmanuel's code and digged into the PG source code (basically at copy.c) to
create a trigger function that insert to the partitioned table direct
(using heap_insert instead of SQL) [3], and the improvement was about
100% (not 4/5 times like got by Emmanuel ). The function has no other
performance trick, like caching the relations or something like that.
The function does partition based on month/year, but it's easy to change to day/month/year or something else. And, of course, it's not ready for production, as I'm not sure if it can break things.
The tests were made using a PL/pgSQL code to insert 1 milion rows, and I
don't know if this is a real-life-like test (probably not). And there
is a table partitioned by month, with a total of 12 partitions (with the
insertions randomly distributed through all 2012).
I put the trigger and the experiments on a repository at GitHub:
https://github.com/matheusoliveira/pg_partitioning_tests
I don't know if this is the right list for the topic, and I thought the old one has to many messages, so I created this one to show this tirgger sample and see if someone has a comment about it.
PS: I'd be glad if someone could revise the code to make sure it don't brake in some
corner case. I'm made some tests [4], but not sure if they
covered everything.
PS2: It surely will not work on old versions of PostgreSQL, perhaps not even 9.1 (not tested).
[1] http://archives.postgresql.org/pgsql-hackers/2008-12/msg01221.php and http://archives.postgresql.org/pgsql-performance/2012-12/msg00189.php
[2] https://github.com/matheusoliveira/pg_partitioning_tests/blob/master/src/spi/partition_insert_trigger_spi.c
[3] https://github.com/matheusoliveira/pg_partitioning_tests/blob/master/src/partition_insert_trigger.c
[4] https://github.com/matheusoliveira/pg_partitioning_tests/tree/master/test/regress
Regards,
--
Matheus de Oliveira
Analista de Banco de Dados
Dextra Sistemas - MPS.Br nível F!
www.dextra.com.br/postgres
