> We face in a PostgreSQL 11.4 installation on a potent Linux host a
> ...
> Why is this (ignoring the Index) and what could be done?
> Why is this (ignoring the Index) and what could be done?
IMHO: 11.4 is very old. ( Release date: 2019-06-20 ) and missing a lot of patches.
The latest patch release is 11.14 ( see https://www.postgresql.org/docs/11/release.html )
You can test the PG11.14 with the PostgreSQL docker image ( https://hub.docker.com/_/postgres )
- docker pull postgres:11.14-bullseye
- import table ( d01buch )
- create indexes
- test your query
Regards,
Imre
Matthias Apitz <guru@xxxxxxxxxxx> ezt írta (időpont: 2022. jan. 26., Sze, 11:55):
Hello,
We face in a PostgreSQL 11.4 installation on a potent Linux host a
serious performance degree.
A SELECT with a LIKE clause on a table with ca. 5.200.000 rows on a
column with an Index ignores this and does a full table scan:
sisis=# explain (analyze, buffers) select * from d01buch where d01ort like 'Z 9610%' ;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------
Gather (cost=1000.00..680262.71 rows=510 width=952) (actual time=1324.096..1349.429 rows=1 loops=1)
Workers Planned: 4
Workers Launched: 4
Buffers: shared hit=102040 read=560674
-> Parallel Seq Scan on d01buch (cost=0.00..679211.71 rows=128 width=952) (actual time=1117.663..1315.062 rows=0 loops=5)
Filter: (d01ort ~~ 'Z 9610%'::text)
Rows Removed by Filter: 1055853
Buffers: shared hit=102040 read=560674
Planning Time: 2.028 ms
Execution Time: 1349.593 ms
(10 Zeilen)
Why is this (ignoring the Index) and what could be done?
Thanks
matthias
--
Matthias Apitz, ✉ guru@xxxxxxxxxxx, http://www.unixarea.de/ +49-176-38902045
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