Re: BUG #16109: Postgres planning time is high across version - 10.6 vs 10.10

Andres Freund <andres@anarazel.de>

From: Andres Freund <andres@anarazel.de>
To: Mukesh Chhatani <chhatani.mukesh@gmail.com>
Cc: pgsql-bugs@postgresql.org
Date: 2019-11-13T18:42:13Z
Lists: pgsql-bugs, pgsql-hackers
Hi,

On 2019-11-13 11:37:30 -0700, Mukesh Chhatani wrote:
> FYI.. default_statistics_target was set to 10000 but I changed it 100 and
> even to 1000 and still planning time was high.

Note that you'd need to ANALYZE the involved tables before that change
actually would effect planning time.


> Update I was able to resolve the problem by changing - partitioned tables to
> single table and changing data type of 2 columns used in the joins from
> varchar to varchar(50).

That's not going to be the fix. There's no efficiency difference between
those. It's more likely that, that the different statistics target would
have taken effect after the alter table etc.

- Andres



Commits

  1. Include information on buffer usage during planning phase, in EXPLAIN output, take two.

  2. Include information on buffer usage during planning phase, in EXPLAIN output.

  3. Expose BufferUsageAccumDiff().