On 26.2.2015 18:34, Tom Lane wrote: > Tomas Vondra <tomas.von...@2ndquadrant.com> writes: >> FWIW this apparently happens because the code only expect that >> EquivalenceMembers only contain Var, but in this particular case that's >> not the case - it contains RelabelType (because oprcode is regproc, and >> needs to be relabeled to oid). > > If it thinks an EquivalenceMember must be a Var, it's outright > broken; I'm pretty sure any nonvolatile expression is possible.
I came to the same conclusion, because even with the RelabelType fix it's trivial to crash it with a query like this: SELECT 1 FROM pg_proc p JOIN pg_operator o ON oprcode = (p.oid::int4 + 1); I think fixing this (e.g. by restricting the optimization to Var-only cases) should not be difficult, although it might be nice to handle generic expressions too, and something like examine_variable() should do the trick. But I think UNIQUE indexes on expressions are not all that common. -- Tomas Vondra http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers