Jerry Gamache writes:
On 8.1, I have a very interesting database where the distributions of
some values in a multi-million rows table is logarithmic (i.e. the most
frequent value is an order of magnitude more frequent than the next
ones). If I analyze the table, the statistics become extremely skewed
towards the most frequent values and this prevents the planner from
giving any good results on queries that do not target these entries.
Highly skewed distributions are hardly unusual, and I'm not aware that
the planner is totally incapable of dealing with them. You do need a
large enough stats target to get down into the tail of the
distribution (the default target for 8.1 is probably too small for you).
It might be that there have been some other relevant improvements since
8.1, too ...

regards, tom lane

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grouppgsql-performance @
postedJul 7, '10 at 9:03p
activeJul 7, '10 at 9:22p

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Jerry Gamache: 1 post Tom Lane: 1 post



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