Perez wrote:
> I thought, from watching the list for a while, that the planner
> statistics needed were known but that how to gather the statistics
> was not?

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I think over the course of the discussion we have figured out that we
would like to have cross-column correlation statistics. The precise
mathematical incarnation hasn't been determined yet, as far as I can
see. Collecting the statistics thereafter isn't that hard, but there
needs to be a way to not collect an exponential volume of statistics on
all column combinations.
--
Peter Eisentraut
http://developer.postgresql.org/~petere/
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match