Gaetano Mendola wrote:
> Tom Lane wrote:
>
>>
>> Hm, it sure looks to be exactly the same plan. The performance
>> difference seems to be just that the seqscans are faster. I surmise
>> that in the 7.3 database you had a lot of dead rows, or at least a lot
>> of free space. Possibly you need to vacuum more often to keep down the
>> amount of junk in the tables.
>
>
> The two databases were created from scratch and the first
> operation on it ( after a vacuum analyze ) was just that query.
>
> I will try to pump up the statistic target.
The default_statistics_target was already 1000 for
postgres7.4beta2 and after setting this value to 1000
for postgres7.3.3 I had the same explain with the same
expected row ( almost 400 ) and the almost the same time execution.
Another piece: The query
SELECT ud.*
FROM user_data ud, class_default cd
WHERE ud.id_class = cd.id_class AND cd.id_provider = 39;
( I removed the huge table )
take just few ms to be executed.
Regards
Gaetano Mendola
