On Wed, 2010-12-22 at 07:36 -0800, David Fetter wrote: > > > > > > 7. Why does ANALYZE skip foreign tables? Surely its really > > > > important we know things about a foreign table, otherwise we are > > > > going to optimize things very badly. > > > > > > Quite apart from other reasons, such as possible ephemerality of > > > the data, the difficulty of taking a reasonable random sample from > > > an arbitrary foreign data source seems substantial, and we surely > > > don't want ANALYSE to have to run a full sequential scan of a > > > foreign data source. > > > > I think we need something that estimates the size of a table, at > > least, otherwise queries will be completely un-optimised. > > The estimated size for a lot of things--streams of data, for > example--is infinity. I suppose that's a good default for some cases.
A fairly gross estimate will be all that is required. Without it, we'd better be looking at some advanced query-cancel support, cos the "17 hours and still going" events of previous SQL gateway products seems to be looming in my rear view mirror. -- Simon Riggs http://www.2ndQuadrant.com/books/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
