Re: Query planner wants to use seq scan

On 27.10.2015 23:56, Bertrand Paquet wrote:
> So,
>
> Tonight, the index on the three field is used, may be my yesterday
> vacuum updated stats.
>
> Thx you for your help.
>
> Regards,
>
> Bertrand
>
>
>
>
> 2015-10-27 18:33 GMT+01:00 Bertrand Paquet
> <bertrand(dot)paquet(at)doctolib(dot)fr <mailto:bertrand(dot)paquet(at)doctolib(dot)fr>>:
>
> Hi tom,
>
> I did the test yesterday with an index on the three fields, and
> with a partial index on organization and status and where is null
> condition on handled. I saw no modification on query plan.
> May be I forgot to analyze vacuum after. I will retry tonight.
>
> I use a btree index. Is it the good solution, even with the In
> clause ?
>
> Regards,
>
> Bertrand
>
> Le mardi 27 octobre 2015, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us
> <mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us>> a écrit :
>
> Bertrand Paquet <bertrand(dot)paquet(at)doctolib(dot)fr> writes:
> > We have a slow query. After analyzing, the planner decision
> seems to be
> > discutable : the query is faster when disabling seqscan. See
> below the two
> > query plan, and an extract from pg_stats.
>
> > Any idea about what to change to help the planner ?
>
> Neither one of those plans is very good: you're just hoping
> that the
> Filter condition will let a tuple through sooner rather than
> later.
>
> If you care about the performance of this type of query, I'd
> consider
> creating an index on (organization_id, status, handled_by) so
> that all
> the conditions can be checked in the index.
>
> regards, tom lane
>
>
Hello Bertrand once again!
What's your status? Does the plan changed after deploying three field
index ?

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Alex Ignatov
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