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copied!<p>when you create a table, you get an exclusive lock on it that lasts to the end of the transaction. Even if you then go ahead and drop it.</p> <p>So if I start a tx and create a temp table:</p> <pre><code>steve@steve@[local] *=# create temp table foo(foo_id int); CREATE TABLE steve@steve@[local] *=# select * from pg_locks where pid = pg_backend_pid(); locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted ---------------+----------+-----------+------+-------+------------+---------------+---------+-----------+----------+--------------------+-------+---------------------+--------- virtualxid | | | | | 2/105315 | | | | | 2/105315 | 19098 | ExclusiveLock | t transactionid | | | | | | 291788 | | | | 2/105315 | 19098 | ExclusiveLock | t relation | 17631 | 10985 | | | | | | | | 2/105315 | 19098 | AccessShareLock | t relation | 17631 | 214780901 | | | | | | | | 2/105315 | 19098 | AccessExclusiveLock | t object | 17631 | | | | | | 2615 | 124616403 | 0 | 2/105315 | 19098 | AccessExclusiveLock | t object | 0 | | | | | | 1260 | 16384 | 0 | 2/105315 | 19098 | AccessShareLock | t (6 rows) </code></pre> <p>These 'relation' locks aren't dropped when I drop the table:</p> <pre><code>steve@steve@[local] *=# drop table foo; DROP TABLE steve@steve@[local] *=# select * from pg_locks where pid = pg_backend_pid(); locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted ---------------+----------+-----------+------+-------+------------+---------------+---------+-----------+----------+--------------------+-------+---------------------+--------- virtualxid | | | | | 2/105315 | | | | | 2/105315 | 19098 | ExclusiveLock | t object | 17631 | | | | | | 1247 | 214780902 | 0 | 2/105315 | 19098 | AccessExclusiveLock | t transactionid | | | | | | 291788 | | | | 2/105315 | 19098 | ExclusiveLock | t relation | 17631 | 10985 | | | | | | | | 2/105315 | 19098 | AccessShareLock | t relation | 17631 | 214780901 | | | | | | | | 2/105315 | 19098 | AccessExclusiveLock | t object | 17631 | | | | | | 2615 | 124616403 | 0 | 2/105315 | 19098 | AccessExclusiveLock | t object | 17631 | | | | | | 1247 | 214780903 | 0 | 2/105315 | 19098 | AccessExclusiveLock | t object | 0 | | | | | | 1260 | 16384 | 0 | 2/105315 | 19098 | AccessShareLock | t (8 rows) </code></pre> <p>In fact, it added two more locks... It seems if I continually create/drop that temp table, it adds 3 locks each time.</p> <p>So I guess one answer is that you will need enough locks to cope with all these tables being added/dropped throughout the transaction. Alternatively, you could try to reuse the temp tables between queries, simply truncate them to remove all the temp data?</p>

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