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From: =?UTF-8?Q?Gabriel_S=C3=A1nchez?= <gabrielesanchez@gmail.com>
Date: Wed, 1 Apr 2026 10:56:20 -0400
Message-ID: <CANHuRqH7q6bi7UAmW3w+o=11Sy1pzoY5KYsLfkpjS3X3T_OQHw@mail.gmail.com>
Subject: How to query with more workers on a large table with many partitions
To: Postgres General <pgsql-general@postgresql.org>
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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

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<div dir=3D"ltr"><div>Hi PostgreSQL community,</div><div><br></div><div>I h=
ave a large table (86 GB) that is declaratively partitioned by year, sub-pa=
rtitioned by month, and sub-sub-partitioned by day. It currently has 437 le=
af partitions, and will continue to grow with a new partition each day. Whe=
n I query a simple count(*) by date, the query planner plans a query with f=
ive workers, but I have the following in postgresql.conf:</div><div><br></d=
iv><div>max_worker_processes =3D 12</div><div>max_parallel_workers_per_gath=
er =3D 12</div><div>max_parallel_workers =3D 12</div><div>shared_buffers =
=3D 32GB</div><div>temp_buffers =3D 1GB</div><div>work_mem =3D 512MB</div><=
div><br></div><div>The top-level partitioned table has been ANALYZEd.</div>=
<div><br></div><div>I&#39;m running PostgreSQL 16 on an AWS EC2 instance wi=
th 16 logical processors and 128G of RAM. How can I get PG to run the query=
 with more workers?=C2=A0</div><div><br></div><div>Thank you,</div><div>Gab=
riel</div><div><br></div><div><br></div></div>

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