Re: BUG #5226: Limit operator slows down

On Wed, Dec 2, 2009 at 11:42 AM, Craig Ringer
<craig(at)postnewspapers(dot)com(dot)au> wrote:
> On 2/12/2009 10:35 PM, aftab wrote:
>>
>> The following bug has been logged online:
>>
>> Bug reference:      5226
>> Logged by:          aftab
>> Email address:      akhangd(at)hotmail(dot)co(dot)uk
>> PostgreSQL version: 8.3.8
>> Operating system:   Centos 5
>> Description:        Limit operator slows down
>> Details:
>>
>> S1="SELECT *
>> FROM position WHERE
>> position.POSITION_STATE_ID=2 AND
>> position.TARGET_ID=18
>> ORDER BY position.ID DESC
>> ";
>> S2="SELECT *
>> FROM position WHERE
>> position.POSITION_STATE_ID=2 AND
>> position.TARGET_ID=18
>> ORDER BY position.ID DESC
>> LIMIT 1
>> ";
>>
>> S1 takes 0.16ms compared to S2 which takes 5 secs. Both S1 and S2 are same
>> except "LIMIT 1 " is added to S2.
>
> Please read this:
>
>  http://wiki.postgresql.org/wiki/Guide_to_reporting_problems
>
> then re-post your question to the pgsql-general mailing list, including
> appropriate EXPLAIN ANALYZE output for both queries, etc.

Or pgsql-performance.

...Robert