Partitioned tables and locks

James Sewell <james.sewell@jirotech.com> writes:

Is it expected that a lock on a partitioned table will take out 2 locks per
child regardless of the number of children which are excluded at plan time?

Depends on the details of your query, and on which PG version you're
using, but it's by no means surprising for each child table to get
locked. (I'm not sure where *two* locks would come from, though.)

If you're working with massively partitioned tables, increasing
max_locks_per_transaction is a good idea.

regards, tom lane

Is it expected that a lock on a partitioned table will take out 2 locks
per

child regardless of the number of children which are excluded at plan

time?

Depends on the details of your query, and on which PG version you're
using, but it's by no means surprising for each child table to get
locked. (I'm not sure where *two* locks would come from, though.)

The queries were just select count(*) both with a where clause which
excludes some partitions and without, I’m on 11.

The table has over 3K partitions

If you're working with massively partitioned tables, increasing
max_locks_per_transaction is a good idea.

It’s 256 at the moment, with 600 connections - guess I need more.
--
James Sewell,
Chief Architect

Suite 112, Jones Bay Wharf, 26-32 Pirrama Road, Pyrmont NSW 2009
P (+61) 2 8099 9000 W www.jirotech.com F (+61) 2 8099 9099

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I don't recall the details, but I know v12 included significant
enhancements to lock relations later in the process such that when
targeting relatively few of the partitions, it can be a major performance
boost.