On 09/11/11 23:58, Ruslan A. Bondar wrote: > > Why have you decided it isn't using indexes? > If index exists - postgres will use it. Actually that's not necessarily the case. PostgreSQL will only use an index if (a) the index can be used for that kind of query and (b) using the index will be faster than doing a sequential scan. If a query requires all the data in a table, PostgreSQL is quite likely to do a sequential scan of the table, because it'll need to read every block anyway. Reading just the table (without reading the index) in order is much faster than reading the index then doing semi-random reads of the table. Additionally, not all indexes can be used for all operations. For example, a LIKE query with a prefix wildcard eg "%FRED" cannot use a btree index, so any btree index on the searched field will be ignored. -- Craig Ringer -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
