Lock partitions
in [PgSql]
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From: Mark Wong on 18 Oct 2006 12:54 Tom Lane wrote: > Mark Wong <markw(a)osdl.org> writes: >> The number of transaction errors increased when I increased the >> NUM_LOCK_PARTITIONS, which I think is the reason it failed to run when I >> set it to 16. > > Hmm, what sort of errors are we talking about? I wonder if you've > exposed a bug. Changing NUM_LOCK_PARTITIONS really shouldn't have any > semantic effect. The libpq client (error log: http://dbt.osdl.org/dbt/dbt2dev/results/dev4-015/180/client/error.log) is saying things like this: ERROR: too many LWLocks taken CONTEXT: SQL statement "DELETE FROM new_order WHERE no_o_id = 2101 AND no_w_id = 349 AND no_d_id = 1" A grep through that file shows that all the unexpected errors appear to be due to "too many LWLocks taken". Mark ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
From: Tom Lane on 18 Oct 2006 13:18 Mark Wong <markw(a)osdl.org> writes: > Tom Lane wrote: >> Hmm, what sort of errors are we talking about? > ERROR: too many LWLocks taken That really shouldn't happen ... are you sure you did a full recompile after changing NUM_LOCK_PARTITIONS? Actually ... wait a moment. The default value of NUM_LOCK_PARTITIONS is already 16 (1 << LOG2_NUM_LOCK_PARTITIONS where the latter is 4). Are you saying you set LOG2_NUM_LOCK_PARTITIONS to 16? That would be way too many partitions. I was thinking of testing LOG2_NUM_LOCK_PARTITIONS in the range of about 2 to 5. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
From: Mark Wong on 18 Oct 2006 13:22
Tom Lane wrote: > Mark Wong <markw(a)osdl.org> writes: >> Tom Lane wrote: >>> Hmm, what sort of errors are we talking about? > >> ERROR: too many LWLocks taken > > That really shouldn't happen ... are you sure you did a full recompile > after changing NUM_LOCK_PARTITIONS? > > Actually ... wait a moment. The default value of NUM_LOCK_PARTITIONS > is already 16 (1 << LOG2_NUM_LOCK_PARTITIONS where the latter is 4). > Are you saying you set LOG2_NUM_LOCK_PARTITIONS to 16? That would be > way too many partitions. I was thinking of testing > LOG2_NUM_LOCK_PARTITIONS in the range of about 2 to 5. Oops, I can't read bit shifting. =p I'll do again. Mark ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq |