| From: | Luc Vlaming <luc(at)swarm64(dot)com> |
|---|---|
| To: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | allow partial union-all and improve parallel subquery costing |
| Date: | 2020-10-13 08:57:23 |
| Message-ID: | FRXPR01MB09021F98988B057A636AA4EEB7040@FRXPR01MB0902.DEUPRD01.PROD.OUTLOOK.DE |
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| Lists: | pgsql-hackers |
Hi,
While developing some improvements for TPC-DS queries I found out that with
UNION ALL partial paths are not emitted. Whilst fixing that I also came across
the subquery costing which does not seem to consider parallelism when doing
the costing.
I added a simplified testcase in pg-regress to show this goes wrong, and
attached also a before and after explain output of tpc-ds SF100 query 5
based on version 12.4.
I hope I followed all etiquette and these kind of improvements are welcome.
Kind regards,
Luc
Swarm64
| Attachment | Content-Type | Size |
|---|---|---|
| v1-0001-Allow-partial-UNION-ALL-improve-parallel-subquery.patch | text/x-patch | 5.0 KB |
| tpcds-q5-before.txt | text/plain | 9.7 KB |
| tpcds-q5-after.txt | text/plain | 9.1 KB |
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