"Chris Hoover" <revoohc@gmail.com> writes: > SELECT rev_desc FROM rev_code_desc WHERE rev_code = lpad('0300', 4, '0') > Is there anyway to make postgres use an index on this query? > Here is the table definition: > CREATE TABLE rev_code_desc > ( > rev_code character(4) NOT NULL, Since rev_code is char(n), you need to cast the other thing to char(n) as well: SELECT rev_desc FROM rev_code_desc WHERE rev_code = lpad('0300', 4, '0')::char(4) lpad() is declared to return text, which means that your original query resolves as ... WHERE rev_code::text = lpad('0300', 4, '0'), which means that the index on rev_code is useless (since it has bpchar semantics not text semantics). If changing the queries seems impractical, you could add an index on rev_code::text, or reconsider the choice of column type. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq

"Chris Hoover" <revoohc@gmail.com> writes: > On Nov 15, 2007 11:25 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote: >> If changing the queries seems impractical, you could add an index on >> rev_code::text, or reconsider the choice of column type. > how would you create this index? create index rev_code_text_idx on > rev_code_desc(rev_code::text) fails complaining "ERROR: syntax error > at or near "::"" You need more parentheses --- read the docs about expression indexes. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings