On Mon, Aug 18, 2014 at 2:21 PM, Matheus de Oliveira <matioli.matheus@xxxxxxxxx> wrote: > Do you really need such large values? What is your max_connections value? max_connections = 450 ...we have found that we run out of shared memory when max_pred_locks_per_transaction is less than 30k. On Mon, Aug 18, 2014 at 2:29 PM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote: > performance of any query to pg_locks is proportional to the setting of > max_locks_per_transaction. still, something is awry here. can you > 'explain' that query? tudb=# explain SELECT mode, count(mode) AS count FROM pg_locks GROUP BY mode ORDER BY mode; QUERY PLAN ------------------------------------------------------------------------------------- Sort (cost=0.63..0.65 rows=200 width=32) Sort Key: l.mode -> HashAggregate (cost=0.30..0.32 rows=200 width=32) -> Function Scan on pg_lock_status l (cost=0.00..0.10 rows=1000 width=32) (4 rows) > SELECT COUNT(*) from pg_locks; ERROR: invalid memory alloc request size 1562436816 -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance