Diego Manilla Suárez wrote: > Hi. I found this somewhere: > > select a from b order by a using ~<~ > > I've been searching the docs but I found nothing about this weird ~<~ > comparator. Not in comparison operators, String functions and operators, > nor the order by clause. Maybe it has something to do with regular > expressions, but so far I haven't found anything. It's part of the text pattern operator family (also varchar, bpchar and name patterns). When you define an index you can specify text_pattern_ops to be used rather than the default comparison. This lets you have LIKE 'abc%' use the index when you have a non-C locale (where sorting isn't strictly alphabetic). Of course, such an index is only usable by pattern-matching operations not locale-aware < or >, so you might want two indexes on the same column(s). It's covered in the manuals under Indexes / Operator Classes (although it doesn't seem to feature in the A-Z index). Useful ways to explore operators: \do ~>~ SELECT * FROM pg_operator WHERE oprname = '~>~'; SELECT * FROM pg_operator WHERE oprcode::text LIKE 'text_pattern%'; HTH -- Richard Huxton Archonet Ltd -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
