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* How to query with more workers on a large table with many partitions
@ 2026-04-01 14:56 Gabriel Sánchez <[email protected]>
2026-04-01 15:05 ` Re: How to query with more workers on a large table with many partitions Greg Hennessy <[email protected]>
0 siblings, 1 reply; 2+ messages in thread
From: Gabriel Sánchez @ 2026-04-01 14:56 UTC (permalink / raw)
To: pgsql-general
Hi PostgreSQL community,
I have a large table (86 GB) that is declaratively partitioned by year,
sub-partitioned by month, and sub-sub-partitioned by day. It currently has
437 leaf partitions, and will continue to grow with a new partition each
day. When I query a simple count(*) by date, the query planner plans a
query with five workers, but I have the following in postgresql.conf:
max_worker_processes = 12
max_parallel_workers_per_gather = 12
max_parallel_workers = 12
shared_buffers = 32GB
temp_buffers = 1GB
work_mem = 512MB
The top-level partitioned table has been ANALYZEd.
I'm running PostgreSQL 16 on an AWS EC2 instance with 16 logical processors
and 128G of RAM. How can I get PG to run the query with more workers?
Thank you,
Gabriel
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: How to query with more workers on a large table with many partitions
2026-04-01 14:56 How to query with more workers on a large table with many partitions Gabriel Sánchez <[email protected]>
@ 2026-04-01 15:05 ` Greg Hennessy <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Greg Hennessy @ 2026-04-01 15:05 UTC (permalink / raw)
To: [email protected]
> I'm running PostgreSQL 16 on an AWS EC2 instance with 16 logical
> processors and 128G of RAM. How can I get PG to run the query with
> more workers?
>
Postgres allocates more workers based on the log3 of the ratio of the
table size to min_parallel_table_scan_size.
You may want to try |ALTER TABLE ... SET (parallel_workers = 10) (or
whatever your desired value is).
|
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2026-04-01 14:56 How to query with more workers on a large table with many partitions Gabriel Sánchez <[email protected]>
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