[postgis-users] Performance Help

[Mark Cave-Ayland]

On Thu, 2007-07-26 at 11:51 +0000, Alan Cunnane wrote:
> I have actually already looked at PG routing however because of the
> constraints of this particular project I cannot use it. I have to use
> SQL queries as I was attempting however it seems that the query runs
> smoothly enough up until the 8th or 9th table is added to the join. Is
> this my own fault in the query or is this just the performance of
> Postgresql in handling a large number of joins? I do appreciate your
> help and advice,
> 
> Alan

Tricky :(

I guess the only thing you can do in that case is check the query plans
just before and just after the point at which the query plan
deteriorates and try and spot the difference.

Are you allowed to use stored procedures for your solution? Due to the
recursive-type nature of some of the queries you will need, it may be
possible to come up with something more efficient that way.


HTH,

Mark.

-- 
ILande - Open Source Consultancy
http://www.ilande.co.uk