Re: Slow update with simple query - Mailing list pgsql-performance

From Tom Lane
Subject Re: Slow update with simple query
Date
Msg-id 8399.1166028385@sss.pgh.pa.us
Whole thread Raw
In response to Re: Slow update with simple query  (Arnaud Lesauvage <thewild@freesurf.fr>)
Responses Re: Slow update with simple query  (Mark Lewis <mark.lewis@mir3.com>)
Re: Slow update with simple query  (Arnaud Lesauvage <thewild@freesurf.fr>)
List pgsql-performance
Arnaud Lesauvage <thewild@freesurf.fr> writes:
> Indeed, the new query does not perform that well :

> "Hash Join  (cost=112.75..307504.97 rows=2024869 width=355) (actual time=53.995..246443.811 rows=2020061 loops=1)"
> ...
> "Total runtime: 2777844.892 ms"

> I removed all unnecessary indexes on t1 before running the query (I left the index on uid and the multicolumn index
containindthe updated field). 
> I believe the multicolumn-functional-index computation is taking some time here, isn't it ?

Given that the plan itself only takes 246 sec, there's *something*
associated with row insertion that's eating the other 2500+ seconds.
Either index entry computation or constraint checking ...

            regards, tom lane

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