2010/12/13 Josh Berkus <j...@agliodbs.com>: > 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.
It's really good idea? Composite index can be created when single columns are too less unique - (name, surname). DBA specification can be cheeper. We can set a options for relation? So it can be used. Pavel > > 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 > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
