Re: Transitive Closure and 'pg_inherits' - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Transitive Closure and 'pg_inherits'
Date
Msg-id 11594.1112548389@sss.pgh.pa.us
Whole thread Raw
In response to Transitive Closure and 'pg_inherits'  (Ioannis Theoharis <theohari@ics.forth.gr>)
List pgsql-hackers
Ioannis Theoharis <theohari@ics.forth.gr> writes:
> My question is whether the way, in wich postgresql do this task, is a
> transitive closure on table 'pg_inherits' or there is a better approach
> implemented (like numbering scheme techniques etc.) ?

It's a transitive closure, and not a very bright one at that; see
find_all_inheritors(), find_inheritance_children(), and particularly
the comments to the latter.  However, we've not heard reports indicating
that this is a serious bottleneck in any real-world situation, so
no one has spent time to improve it.  (I'd expect the per-table planning
costs to vastly outweigh the cost of finding those tables, anyway.)
        regards, tom lane


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