Tom Lane <t...@sss.pgh.pa.us> writes: > Actually, in the problematic cases, it's interesting to consider the > following strategy: when scalarineqsel notices that it's being asked for > a range estimate that's outside the current histogram bounds, first try > to obtain the actual current max() or min() of the column value --- this > is something we can get fairly cheaply if there's a btree index on the > column. If we can get it, plug it into the histogram, replacing the > high or low bin boundary. Then estimate as we currently do. This would > work reasonably well as long as re-analyzes happen at a time scale such > that the histogram doesn't move much overall, ie, the number of > insertions between analyzes isn't a lot compared to the number of rows > per bin. We'd have some linear-in-the-bin-size estimation error because > the modified last or first bin actually contains more rows than other > bins, but it would certainly work a lot better than it does now.
I know very little about statistics in general, but your proposal seems straigth enough for me to understand it, and looks good: +1. Regards, -- dim -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
