Re: VPD vs Multiple Schemas

Obviously anyone with a brain will take the advice of Mr JL and Mr TK seriously to heart.

I'd just like to offer a couple of quick "from experience" points about VPD.
(1) There are the odd implementation restriction once you jump into
VPD. For instance you can't use Merge on tables that have VPD policies enabled. No biggy, but it's nice to go into these things with your eyes open.

(2) VPD does loads of cool and unexpected things for you in terms of
managing predicates when you join tables with VPD policies on them (I'm thinking especially in of views here). However there are always the odd glitch and gotcha, I've spent quite a few hours scratching my head over a bizzare and inexplicable execution plan that created a random sudden performance nightmare because of the way VPD works ( 10.1.0.3, can't vouch for 10.2 as yet ). Sometimes it's hard to keep saying "well, VPD unexpectedly did this..." in the board room.

For instance, I once resorted to the ASNI "from table_a natural join table_b" syntax to hide the fact that if I specifically included the apparently redundant VPD predicate in a query I got a completely different (and much better) plan than if I didn't. Received on Sun Oct 08 2006 - 17:40:34 CDT