On 2/26/24 01:06, Emiel Mols wrote:
On Mon, Feb 26, 2024 at 3:50 PM Daniel Gustafsson <daniel@xxxxxxxx
<mailto:daniel@xxxxxxxx>> wrote:
There is a measurable overhead in connections, regardless of if they
are used
or not. If you are looking to squeeze out performance then doing
more over
already established connections, and reducing max_connections, is a
good place
to start.
Clear, but with database-per-test (and our backend setup), it would have
been *great* if we could have switched database on the same connection
(similar to "USE xxx" in mysql). That would limit the connections to the
amount of workers, not multiplied by tests.
That is because:
https://dev.mysql.com/doc/refman/8.3/en/glossary.html#glos_schema
"In MySQL, physically, a schema is synonymous with a database. You can
substitute the keyword SCHEMA instead of DATABASE in MySQL SQL syntax,
for example using CREATE SCHEMA instead of CREATE DATABASE. "
Even with a pooler, we're still going to be maintaining 1000s of
connections from the backend workers to the pooler. I would expect this
to be rather efficient, but still unnecessary. Also, both
pgbouncer/pgpool don't seem to support switching database in-connection
(they could have implemented the aforementioned "USE" statement I
think!). [Additionally we're using PHP that doesn't seem to have a good
shared memory pool implementation -- pg_pconnect is pretty buggy].
I'll continue with some more testing. Thanks for now!
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
