Re: select query takes 13 seconds to run with index

mark wrote:
> Hi, is there anyway this can be made faster?  id is the primary key,
> and there is an index on uid..
>
> thanks
>
>
> EXPLAIN ANALYZE select * from pokes where uid = 578439028 order by id
> DESC limit 6;
>                                                                      QUERY PLAN
>
----------------------------------------------------------------------------------------------------------------------------------------------------
>  Limit  (cost=0.00..9329.02 rows=6 width=135) (actual
> time=13612.247..13612.247 rows=0 loops=1)
>    ->  Index Scan Backward using pokes_pkey on pokes
> (cost=0.00..5182270.69 rows=3333 width=135) (actual
> time=13612.245..13612.245 rows=0 loops=1)
>          Filter: (uid = 578439028)
>  Total runtime: 13612.369 ms
> (4 rows)
>
>
First this should be posted on performance list.

how many records are in this table?  The uid 578,439,028 assuming this
is auto incremented key  that started 1 this means there is 578 million
records in the table.

The estimate is way off, when was the last time Vaccum was on the table?

What verison of Postgresql are you running
Size of the Table
Table layout
Load on the database