Tomas, > (a) find out what statistics do we need to collect and how to use it > (b) implement a really stupid inefficient solution > (c) optimize in iterations, i.e. making it faster, consuming less > space etc.
I'll suggest again how to decide *which* columns to cross: whichever columns are combined in composite indexes. In version 2, allow the DBA to specify combinations. In the unlikely event that correlation could be reduced to a single float number, it would be conceivable for each column to have an array of correlation stats for every other column where correlation was non-random; on most tables (i.e. ones with less than 100 columns) we're not talking about that much storage space. The main cost would be the time spent collecting that info ... -- -- Josh Berkus PostgreSQL Experts Inc. http://www.pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers