Re: Wrong example in the bloom documentation

On Sat, Oct 17, 2020 at 01:50:26PM +0000, Daniel Westermann (DWE) wrote:
> On Fri, Oct  9, 2020 at 11:08:32AM -0400, Bruce Momjian wrote:
> >This is not applying to PG 12 or earlier because the patch mentions JIT,
> >which was only mentioned in the PG bloom docs in PG 13+.
>
> Does that mean we need separate patches for each release starting with 10?
> As I am not frequently writing patches, I would need some help here.

I can regenerate the output for older versions using your patch.
However, I am confused about the parallelism you are seeing. Your patch
shows:

Without the two indexes being created, a parallel sequential scan will happen for the query below:
-------------------
<programlisting>
=# EXPLAIN ANALYZE SELECT * FROM tbloom WHERE i2 = 898732 AND i5 = 123451;
QUERY PLAN
---------------------------------------------------------------------------------------------------
Seq Scan on tbloom (cost=0.00..214.00 rows=1 width=24) (actual time=2.729..2.731 rows=0 loops=1)
Filter: ((i2 = 898732) AND (i5 = 123451))
Rows Removed by Filter: 10000
Planning Time: 0.257 ms
Execution Time: 2.764 ms
(5 rows)

However, I don't see any parallelism in this output. Also, I don't see
any parallelism once the indexes are created. What PG version is this?
and what config settings did you use? Thanks.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EnterpriseDB https://enterprisedb.com

The usefulness of a cup is in its emptiness, Bruce Lee