On Wed, Feb 13, 2013 at 3:01 PM, Andrew Taylor <andydtaylor@xxxxxxxxx> wrote: > And ended up with a table 13,708,233 rows long with what looks like plenty > of duplicated rows. Some but not all are duplicated. What can I do to sort > this out? It means that (e, n) pairs are not unique in A and B and you got a superposition of them. If you have 5 equal pairs in A and 7 same pairs with in B you will get 35 combinations as a result. And BTW when you use LEFT JOIN if there are rows in A that have no matching pairs in B you will get one row for each of them where lan and lon are NULLs. See the join_type section here http://www.postgresql.org/docs/9.2/static/sql-select.html. -- Sergey Konoplev Database and Software Architect http://www.linkedin.com/in/grayhemp Phones: USA +1 415 867 9984 Russia, Moscow +7 901 903 0499 Russia, Krasnodar +7 988 888 1979 Skype: gray-hemp Jabber: gray.ru@xxxxxxxxx -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general