Andrew Gierth wrote:
> >>>>> "Guillaume" == Guillaume Smet <guillaume.smet@gmail.com> writes:
>
> Guillaume> - "While semi-joins merely replace existing IN joins,
> Guillaume> anti-joins are a new capability for NOT IN and NOT EXIST
> Guillaume> clauses (Tom) This improves optimization possibilities."
> Guillaume> -> remove the "(Tom)", s/EXIST/EXISTS/
>
> Also s/NOT IN and // (anti-joins are not used for NOT IN due to the
> awkward semantics of nulls). Should possibly also mention the fact that
> some outer joins can be planned as anti-joins too.
Thanks, text updated:
While semi-joins merely replace existing IN joins, anti-joins are a new capability for NOT EXISTS clauses
(Tom)This improves optimization possibilities.
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
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