Hi, I have further found that it is only when passing the string in to the function that the slow response occurs. When i call SELECT * FROM _function(IN TEXT) it is very slow on my WHERE clause using LIKE($1||'%') but (run in error), very fast when LIKE('some text'||'%') I have also created and indexed a new column to eliminate the expression and the same happens Andy Hi, I have created an index on an expression as follows: (replace(lower(my_column), ' '::text, ''::text) which i use in a WHERE clause against LIKE 'string%' By using text_pattern_ops i get the index used provided i more than one character is used in the string. However, with the same SELECT query running within a function (using RETURNS TABLE) the query takes significantly longer - as though the index is ignored. e.g. 2500ms instead of 12ms -- View this message in context: http://postgresql.1045698.n5.nabble.com/expression-index-not-used-within-function-tp5778236p5778241.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