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.paquet@doctolib.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@sss.pgh.pa.us> a écrit :

Bertrand Paquet <bertrand.paquet@doctolib.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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