Thanks , i just want to get a correlation of near 0 to understand exactly what correlation , i quite ambiguity about this concept . / Statistical correlation between physical row ordering and logical ordering of the column values. This ranges from -1 to +1. When the value is near -1 or +1, an index scan on the column will be estimated to be cheaper than when it is near zero, due to reduction of random access to the disk. (This column is null if the column data type does not have a < operator.) / I can not explain exactly what is/ physical row ordering and logical ordering/ of the column values , can you explain to me with an simple example ?? -- View this message in context: http://postgresql.1045698.n5.nabble.com/Correlation-in-pg-stats-tp5733524p5733655.html Sent from the PostgreSQL - general mailing list archive at Nabble.com. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
