Re: R: slow seqscan after vacuum analize

On Thu, 5 Feb 2004, Edoardo Ceccarelli wrote:

> BEFORE (copy of the db without having run the vacuum):
>
> explain analyze SELECT * FROM utente where luogorilasciodoc='ciao';
>                                                  QUERY PLAN
>
> --------------------------------------------------------------------------------------
> ----------------------
>  Seq Scan on utente  (cost=0.00..40947.90 rows=1826 width=724) (actual
> time=131.17..856.96 rows=15 loops=1)
>    Filter: (luogorilasciodoc = 'ciao'::bpchar)
>  Total runtime: 857.06 msec
> (3 rows)
>
>
> AFTER (actual db)
> portaportese=# explain analyze SELECT * FROM utente where luogorilasciodoc='ciao';
>                                                 QUERY PLAN
>
> --------------------------------------------------------------------------------------
> --------------------
>  Seq Scan on utente  (cost=0.00..92174.50 rows=3 width=724) (actual
> time=705.41..6458.19 rows=15 loops=1)
>    Filter: (luogorilasciodoc = 'ciao'::bpchar)
>  Total runtime: 6458.29 msec
> (3 rows
>
> Things are worst only for seqscan, when it uses indexscan timing is good.

Only thing I can think of is if storage method had been changed. Not
sure if that would even affect it, or if it could do that by itself.
Just brainstorming.

--

Sam Barnett-Cormack
Software Developer                           |  Student of Physics & Maths
UK Mirror Service (http://www.mirror.ac.uk)  |  Lancaster University