Re: partial indexed not being used.

Tom Lane schreef:
> Ron Arts <ron.arts@neonova.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



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