Re: sub-select in IN clause results in sequential scan

From: Angayarkanni <kangayarkanni(at)gmail(dot)com>
To: Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>
Cc: Anj Adu <fotographs(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: sub-select in IN clause results in sequential scan
Date: 2009-10-29 10:32:38
Message-ID: 2a77004c0910290332x6cb5de43l284fb8060083a414@mail.gmail.com
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2009/10/29 Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>

>
>
> On Wed, Oct 28, 2009 at 6:13 PM, Anj Adu <fotographs(at)gmail(dot)com> wrote:
>
>> Postgres consistently does a sequential scan on the child partitions
>> for this query
>>
>> select * from partitioned_table
>> where partitioned_column > current_timestamp - interval 8 days
>> where x in (select yy from z where colname like 'aaa%')
>>
>> If I replace the query with
>>
>> select * from partitioned_table
>> where partitioned_column > current_timestamp - interval 8 days
>> where x in (hardcode_value)
>>
>> The results are in line with expectation (very fast and uses a Bitmap
>> Index Scan on the column X)
>> \
>
>
> use JOIN luke..
>
>
> --
> GJ
>

Yes you try by using Join

JAK

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