On Tue, Jun 05, 2007 at 05:30:14PM -0400, Steven Flatt wrote:
> (A) LEFT JOIN (B) ON col WHERE B.col IS NULL
>
> These queries are much slower on 8.2 than on 8.1 for what looks like the
> reason outlined above. I have rewritten a few key queries to be of the
> equivalent form:
>
> (A) WHERE col NOT IN (SELECT col FROM (B))
At least those _can_ be rewritten into a sane form. I have an application
with a large FULL OUTER JOIN, where _both_ sides can return NULLs. (It's
basically a diff between a "current" and a "wanted" state.)
It performs reasonably well under both 8.1 and 8.2, though. Fourteen-table
join or so :-)
/* Steinar */
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