Thread: problem with 8.0rc1 not using indexes(solved)

Well, I got my 8.0 RC1 working the same as my 7.4.5 and it is for sure
because of some difference in the SQL engine.

On my 7.4.5 box I had the following in the postgresql.conf file:

enable_seqscan = true  (this is the default setting)
7.4.5 had no problems using the indexes with this setting = true

on 8.0RC1 it refused to use certain indexes if enable_seqscan = true
I set this value to false on 8.0 and my performance came back to the
7.4.5 levels.

Is there some other setting in the conf file that would affect the
optimizer?

The weird part is if I ran each query in the function by itself  Explain
would always report the index being used, but when run in the context of
the function the indexes where not being used.

Thanks,

Tony Caduto

Tony Caduto wrote:
> Well, I got my 8.0 RC1 working the same as my 7.4.5 and it is for sure
> because of some difference in the SQL engine.
>
> On my 7.4.5 box I had the following in the postgresql.conf file:
>
> enable_seqscan = true  (this is the default setting)
> 7.4.5 had no problems using the indexes with this setting = true
>
> on 8.0RC1 it refused to use certain indexes if enable_seqscan = true
> I set this value to false on 8.0 and my performance came back to the
> 7.4.5 levels.
>
> Is there some other setting in the conf file that would affect the
> optimizer?
>
> The weird part is if I ran each query in the function by itself  Explain
> would always report the index being used, but when run in the context of
> the function the indexes where not being used.

Is not solved because is a bad idea run the server with that parameter
disabled.


Regards
Gaetano Mendola