On Tue, May 13, 2025 at 4:37 PM Scott Mead <sc...@meads.us> wrote:

> I'll open by proposing that we prevent the planner from automatically
> selecting parallel plans by default


That seems a pretty heavy hammer, when we have things like
parallel_setup_cost that should be tweaked first.

The recommendation that I give to users is pretty straightforward: "Disable
> automatic parallel query, enable it for queries where you find substantial
> savings and can control the rate of execution."  I always tell users that
> if they're using parallel query for anything that should execute in less
> than 5 minutes, they're probably pushing on the wrong tuning strategy as
> the load induced by the parallel query infrastructure is likely going to
> negate the savings that they're getting.
>

Five minutes?! That's not been my experience. Not claiming parallelism is
perfect yet, but there are plenty of parallel performance savings under the
five minute mark.

Cheers,
Greg

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Crunchy Data - https://www.crunchydata.com
Enterprise Postgres Software Products & Tech Support

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