Re: partial indexed not being used.

From: Ron Arts <ron(dot)arts(at)neonova(dot)nl>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Michael Fuhr <mike(at)fuhr(dot)org>, pgsql-novice(at)postgresql(dot)org
Subject: Re: partial indexed not being used.
Date: 2007-02-12 16:31:57
Message-ID: 45D0967D.5090103@neonova.nl
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-novice

Tom Lane schreef:
> Ron Arts <ron(dot)arts(at)neonova(dot)nl> writes:
>> # select count(*) from cdr where billed = false;
>> count
>> -------
>> 3
>> (1 row)
>
>>> =# explain select cdr.* from cdr where billed = false order by calldate;
>>>
>>> QUERY PLAN
>>> -------------------------------------------------------------------
>>> Sort (cost=37448.75..37526.94 rows=31273 width=465)
>>> Sort Key: calldate
>>> -> Seq Scan on cdr (cost=0.00..20323.81 rows=31273 width=465)
> ^^^^^^^^^^
>>> Filter: (billed = false)
>
> You haven't ANALYZEd this table (lately, or perhaps ever). The planner
> is thus working with a default selectivity estimate (which I think is
> 50% for a bool column --- that seems to match your numbers anyway), and
> that leads it to the conclusion that a seqscan is the right thing.
> Which it would indeed be, if half the table has to be retrieved.
>
> regards, tom lane
>

Oh man,

I totally forgot about analyze because I have it running daily from a script.
And of course the script was broken, and I didn't notice.

Thanks!

Ron

--
NeoNova BV, The Netherlands
Professional internet and VoIP solutions

http://www.neonova.nl Kruislaan 419 1098 VA Amsterdam
info: 020-5628292 servicedesk: 020-5628292 fax: 020-5628291
KvK Amsterdam 34151241

The following disclaimer applies to this email:
http://www.neonova.nl/maildisclaimer

In response to

Browse pgsql-novice by date

  From Date Subject
Next Message Johannes Bruegmann 2007-02-12 16:51:16 Re: relation 12345 is still open
Previous Message Tom Lane 2007-02-12 14:21:34 Re: partial indexed not being used.