It would be very useful if we had some way to warn users about stuff like this. Emitting a NOTICE comes to mind.
This can be valid query
Right, but in my experience it's an extremely uncommon pattern and much more likely to be a mistake (that ends up being very time consuming to debug). That's why I think something like a NOTICE or even a WARNING would be useful. The only thing I don't like about that idea is if you ever did actually want this behavior you'd have to do something to squash the ereport. Though, that's a problem we already have in some places, so perhaps not worth worrying about.
I worked for company where they generated sets of SQL queries as result of transformation from multidimensional query language. Some similar queries are possible there.
I don't thing so using NOTICE or WARNING for any valid query is good idea.
I like the idea of some special extension than can block or raises warning for some strange plans like this or with Cartesian product ...
Regards
Pavel
-- Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX Experts in Analytics, Data Architecture and PostgreSQL Data in Trouble? Get it in Treble! http://BlueTreble.com 855-TREBLE2 (855-873-2532) mobile: 512-569-9461
