On Wed, 28 Nov 2007, Csaba Nagy wrote:
> On Wed, 2007-11-28 at 08:27 -0500, Bill Moran wrote:
>> Is there something wrong with:
>> set enable_seqscan = off
>> ?
>
> Nothing wrong with enable_seqscan = off except it is all or nothing type
> of thing... if you want the big table to never use seqscan, but a medium
> table which is joined in should use it, then what you do ? And setting
> enable_seqscan = off will actually not mean the planner can't use a
> sequential scan for the query if no other alternative exist. In any case
> it doesn't mean "please throw an error if you can't do this without a
> sequential scan".
>
> In fact an even more useful option would be to ask the planner to throw
> error if the expected cost exceeds a certain threshold...
and even better if the option can be overridden for a specific transaction
or connection. that way it can be set relativly low for normal operations,
but when you need to do an expensive query you can change it for that
query.
David Lang