| From: | Michał Kłeczek <michal(at)kleczek(dot)org> | 
|---|---|
| To: | PG-General Mailing List <pgsql-general(at)postgresql(dot)org> | 
| Subject: | Partitionwise aggregate and runtime partition pruning | 
| Date: | 2024-09-26 07:58:18 | 
| Message-ID: | F54D9FEE-0A39-490A-801F-B2858B527D01@kleczek.org | 
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| Lists: | pgsql-general | 
Hi All,
I have a question about partition pruning.
Does runtime partition pruning (ie. pruning performed during execution) work with partition wise aggregates?
1) I have a setup with a mix of foreign (postgres_fdw) and local partitions.
2) I want to perform an aggregate query and I want the aggregates to be pushed down to remote servers.
To make it possible I set enable_partitionwise_aggregate to on.
My observation is that partition pruning works during planning time
But with plan_cache_mode = force_generic_plan, explain analyse execute prepared_stmt(params) shows that
_all_ partitions are scanned (and queries sent to remote severs for all remote partitions).
When I set enable_hashagg to false runtime partition pruning works but no pushdown is taking place.
Am I missing something or runtime partition pruning is not going to work for generic plans and partitionwise aggregates?
Thanks,
Michal
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