AW: postgresql long running query

Hi Liam,

top tuning tip for every relational database is: indexes!

I have adminstrated databases where data was 300 GB and created indexes 600 GB
You may think thats useless redundant but ist definitively not.

Rules for indexing:

Does it make sense to create an index for a table with one or several douzends of entries? -> YES!
Does it make sense to create an index that is optimized for certain queries? -> YES!
Does it make sense to create an index, make the query and drop the index? -> YES

Even with tables with billions of entries you should get answer times of less than a second!
… if you have a good index: date for example where the database engine plays ist full potental.

For example see: https://www.enterprisedb.com/postgres-tutorials/overview-postgresql-indexes

Which indexes do you have?

best,

A

Von: liam saffioti <liam(dot)saffiotti(at)gmail(dot)com>
Gesendet: Freitag, 3. Dezember 2021 12:24
An: pgsql-admin <pgsql-admin(at)lists(dot)postgresql(dot)org>; Julien Rouhaud <rjuju123(at)gmail(dot)com>
Betreff: postgresql long running query

Hello Team,

I have a problem with a query that consumes a long time.
The query' execution plan is :

EXPLAIN ANALYZE SELECT x."HistoryId", x."SlaDefinition" FROM "T_CMN_SLAHISTORY" AS x WHERE x."DefinitionId" = '302';
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------
Bitmap Heap Scan on "T_CMN_SLAHISTORY" x (cost=2144.77..35086.42 rows=139012 width=8) (actual time=58.806..116.874 rows=135498 loops=1)
Recheck Cond: ("DefinitionId" = 302)
Heap Blocks: exact=2175
-> Bitmap Index Scan on "Index-20180712-192739" (cost=0.00..2110.02 rows=139012 width=0) (actual time=57.043..57.045 rows=135498 loops=1)
Index Cond: ("DefinitionId" = 302)
Planning Time: 11.132 ms
Execution Time: 120.320 ms

But, the query execution time was 43min 11seconds in the morning in pgbadger report. I don't understand why the query is taking so long. Can you guide me?

Thank you so much.