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2000b6c10a
Since there is only one place that actually needs the partition check expression, namely ExecPartitionCheck, it's better to fetch it from the relcache there. In this way we will never fetch it at all if the query never has use for it, and we still fetch it just once when we do need it. The reason for taking an interest in this is that if the relcache doesn't already have the check expression cached, fetching it requires obtaining AccessShareLock on the partition root. That means that operations that look like they should only touch the partition itself will also take a lock on the root. In particular we observed that TRUNCATE on a partition may take a lock on the partition's root, contributing to a deadlock situation in parallel pg_restore. As written, this patch does have a small cost, which is that we are microscopically reducing efficiency for the case where a partition has an empty check expression. ExecPartitionCheck will be called, and will go through the motions of setting up and checking an empty qual, where before it would not have been called at all. We could avoid that by adding a separate boolean flag to track whether there is a partition expression to test. However, this case only arises for a default partition with no siblings, which surely is not an interesting case in practice. Hence adding complexity for it does not seem like a good trade-off. Amit Langote, per a suggestion by me Discussion: https://postgr.es/m/VI1PR03MB31670CA1BD9625C3A8C5DD05EB230@VI1PR03MB3167.eurprd03.prod.outlook.com |
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| .. | ||
| aggregatecmds.c | ||
| alter.c | ||
| amcmds.c | ||
| analyze.c | ||
| async.c | ||
| cluster.c | ||
| collationcmds.c | ||
| comment.c | ||
| constraint.c | ||
| conversioncmds.c | ||
| copy.c | ||
| createas.c | ||
| dbcommands.c | ||
| define.c | ||
| discard.c | ||
| dropcmds.c | ||
| event_trigger.c | ||
| explain.c | ||
| extension.c | ||
| foreigncmds.c | ||
| functioncmds.c | ||
| indexcmds.c | ||
| lockcmds.c | ||
| Makefile | ||
| matview.c | ||
| opclasscmds.c | ||
| operatorcmds.c | ||
| policy.c | ||
| portalcmds.c | ||
| prepare.c | ||
| proclang.c | ||
| publicationcmds.c | ||
| schemacmds.c | ||
| seclabel.c | ||
| sequence.c | ||
| statscmds.c | ||
| subscriptioncmds.c | ||
| tablecmds.c | ||
| tablespace.c | ||
| trigger.c | ||
| tsearchcmds.c | ||
| typecmds.c | ||
| user.c | ||
| vacuum.c | ||
| variable.c | ||
| view.c | ||