Join on incompatible types

>>>>> "scott" == scott marlowe <scott(dot)marlowe(at)ihs(dot)com> writes:

[...]

scott> Note here:

scott> Merge Join (cost=1788.68..4735.71 rows=1 width=85) (actual
scott> time=597.540..1340.526 rows=20153 loops=1) Merge Cond:
scott> ("outer".id = "inner".id)

scott> This estimate is WAY off. Are both of those fields indexed
scott> and analyzed? Have you tried upping the statistics target on
scott> those two fields? I assume they are compatible types.

Should I understand that a join on incompatible types (such as integer
and varchar) may lead to bad performances ?

--
Laurent Martelli
laurent(at)aopsys(dot)com Java Aspect Components
http://www.aopsys.com/ http://jac.aopsys.com