>From: Ondrej Ivanič <ondrej.iva...@gmail.com>
>Sent: Saturday, December 7, 2019 2:23 AM
>Cc: pgsql-performance@lists.postgresql.org
><pgsql-performance@lists.postgresql.org>
>Subject: Re: How to run in parallel in Postgres
>
>Hi Lars,
>
>I have two suggestions:
>
>- `xargs` almost always present and it can run in parallel (-P) but script
>needs to be changed:
>for((i=1;i<=28;i++)); do echo "SELECT
>find_overlap_gap_single_cell('test_data.overlap_gap_input_t1','geom',4258,'test_data.overlap_gap_input_t1_res',${I},28);";
> done | xargs -n1 -P 10 psql ...
>
>- `UNION ALL` might trigger parallel execution (you need to mess with the
>cost of the function and perhaps other settings):
>SELECT
> find_overlap_gap_single_cell('test_data.overlap_gap_input_t1','geom',4258,'test_data.overlap_gap_input_t1_res',1,28)
>UNION ALL
>SELECT
> find_overlap_gap_single_cell('test_data.overlap_gap_input_t1','geom',4258,'test_data.overlap_gap_input_t1_res',2,28)
>...
>
>
>Cheers,
>
Hi Ondrej
* Yes using xargs seems be an alternative to GNU parallel and I will have
that in mind.
* I did a test using UNION ALL in the branch
https://github.com/larsop/find-overlap-and-gap/tree/union_all_parallel but I
was not able to trigger Postgres parallel . That may be related to what Justin
say about create tables.
Thanks.
Lars
