Re: Add parallel columns for seq scan and index scan on pg_stat_all_tables and _indexes - Mailing list pgsql-hackers

From Alena Rybakina
Subject Re: Add parallel columns for seq scan and index scan on pg_stat_all_tables and _indexes
Date
Msg-id 09424f5e-4ddf-4830-a21f-161e0427f112@postgrespro.ru
Whole thread Raw
In response to Re: Add parallel columns for seq scan and index scan on pg_stat_all_tables and _indexes  (Bertrand Drouvot <bertranddrouvot.pg@gmail.com>)
List pgsql-hackers

Hi!

Finally found some time to work on this. Tests added on v5 patch (attached).
Maybe I'm not aware of the whole context of the thread and maybe my questions will seem a bit stupid, but honestly
it's not entirely clear to me how this statistics will help to adjust the number of parallel workers.
We may have situations when during overestimation of the cardinality during query optimization a several number of parallel workers were unjustifiably generated and vice versa -
due to a high workload only a few number of workers were generated.
How do we identify such cases so as not to increase or decrease the number of parallel workers when it is not necessary?
-- 
Regards,
Alena Rybakina
Postgres Professional

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