Re: Parallel hints in PostgreSQL with consistent perfromance - Mailing list pgsql-performance

From David G. Johnston
Subject Re: Parallel hints in PostgreSQL with consistent perfromance
Date
Msg-id CAKFQuwYqqdJ+kQTc+1NmtiUn5GsX9i3mdqqY3b538JLYOnjgdQ@mail.gmail.com
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In response to Re: Parallel hints in PostgreSQL with consistent perfromance  (mohini mane <mohini.android@gmail.com>)
List pgsql-performance
On Thursday, December 28, 2023, mohini mane <mohini.android@gmail.com> wrote:
Thank you for your response !!
I am experimenting with SQL query performance for SELECT queries on large tables and I observed that changing/increasing the degree of parallel hint doesn't give the expected performance improvement.

I have executed the SELECT query with 2,4 & 6 parallel degree however every time only 4 workers launched & there was a slight increase in Execution time as well, why there is an increase in execution time with parallel degree 6 as compared to 2 or 4?

Random environmental effects.

Also, analyzing a performance test without understanding how “buffers” are used is largely pointless.

Whatever told you about that comment syntax is hallucinating.

Please don’t reply by top-posting. Inline reply to the comments others make directly and trim as needed.  Simply restating your first email isn’t productive.

You cannot enforce the number of workers used, only the the maximum.  That is you knob.

David J.

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