Re: Inheritance & Indexes

On Wed, 25 Jun 2003, Tom Lane wrote:

> Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> writes:
> > I *think* 7.4 may be smarter about
> > implying these conditions as well.
>
> Not really. AFAIR the Append-style plan is the only thing you can get
> out of the planner for inheritance trees. This works well enough for
> restriction clauses like "id = constant" (since those get pushed down to
> the member tables, much as with UNION ALL), but it just isn't gonna be
> efficient for join situations. And I can't see any realistic way for
> the planner to realize that only some pairs of child tables need be
> joined.

I was actually thinking of the table1.col=table2.col and table1.col=42
implying table2.col=42 when I wrote the above because he was also
wondering why it wasn't using index scans on the table2 tree. Which now
that I have access to my 7.4 box again, it does appear to.