[postgis-users] Odd explain analyze estimates?

[Mark Cave-Ayland]

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net 
> [mailto:postgis-users-bounces at postgis.refractions.net] On 
> Behalf Of strk at refractions.net
> Sent: 04 March 2005 17:23
> To: 'PostGIS Users Discussion'
> Subject: Re: [postgis-users] Odd explain analyze estimates?
> 
> 
> Mark, read carefully the explain analyze outputs.
> It seems normal to me that using subqueries doesn't allow the 
> optimizer to take good decisions, while the query with no 
> subquery has *excellent* estimates, am I reading something wrong ?
> 
> I don't think disabling the JOINSEL will do any better... 
> Anyway we should wait for next report.
> 
> --strk;


Hi strk,

OK looking closer, it appears as if the code returns the default selectivity
if called with two variable arguments in the RESTRICT clause. So you're
right, I don't think we've changed anything serious here. My concern was
really that if we found something seriously wrong that I may not have time
to fix it in time for the 1.0.0 release.


Kind regards,

Mark.

------------------------
WebBased Ltd
South West Technology Centre
Tamar Science Park
Plymouth
PL6 8BT 

T: +44 (0)1752 791021
F: +44 (0)1752 791023
W: http://www.webbased.co.uk