Re: Join on incompatible types

Laurent Martelli wrote:

>>>>>>"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 ?

Conversely, you should enforce strict type compatibility in comparisons for
getting any good plans..:-)

Shridhar