Re: order by slowing down a query by 80 times

On Mon, Jun 28, 2010 at 5:09 PM, Yeb Havinga <yebhavinga(at)gmail(dot)com> wrote:

> Rajesh Kumar Mallah wrote:
>
>> Dear List,
>>
>> just by removing the order by co_name reduces the query time dramatically
>> from ~ 9 sec to 63 ms. Can anyone please help.
>>
> The 63 ms query result is probably useless since it returns a limit of 25
> rows from an unordered result. It is not surprising that this is fast.
>
> The pain is here:
>
> Index Scan using profile_master_co_name on profile_master b
> (cost=0.00..1125295.59 rows=6968 width=25) (actual time=0.097..9193.154
> rows=2212 loops=1)
> Filter: ((co_name IS NOT NULL) AND
> ((co_name_vec)::tsvector @@ to_tsquery('manufacturer'::text)))
>
>
> It looks like seq_scans are disabled, since the index scan has only a
> filter expression but not an index cond.
>

seq_scans is NOT explicitly disabled. The two queries just differed in the
order by clause.

regds
Rajesh Kumar Mallah.

>
> regards,
> Yeb Havinga
>
>
>
>> Regds
>> Rajesh Kumar Mallah.
>>
>