Search Postgresql Archives

Re: How can I manually alter the statistics for a column?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Douglas Alan escribió:

> Hey, while I have you on the line, might you be so kind as to explain why
> this query is so slow?  Shouldn't it just fetch the first row in the table?
> What could be faster than that?
> 
> explain analyze select * from maindb_astobject limit 1;
> >
> >                                                              QUERY
> > PLAN
> >
> > ------------------------------------------------------------------------------------------------------------------------------------
> >  Limit  (cost=0.00..0.04 rows=1 width=78) (actual time=8091.962..8091.965
> > rows=1 loops=1)
> >    ->  Seq Scan on maindb_astobject  (cost=0.00..3358190.12 rows=75426912
> > width=78) (actual time=8091.955..8091.955 rows=1 loops=1)
> >  Total runtime: 8092.040 ms
> > (3 rows)

Maybe there's a bunch of pages with only dead tuples at the start of the
table?  Maybe a lot of empty pages at the start of the table  (If this
is 8.3 you have to consider sync_seqscan as well)

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

-- 
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux