[PERFORM] Index Scan Backward Slow

Hi, We have a query which finds the latest row_id for a particular code. We've found a backwards index scan is much slower than a forward one, to the extent that disabling indexscan altogether actually improves the query time. Can anyone suggest why this might be, and what's best to do to

Re: [PERFORM] Index Scan Backward Slow

Simple... that did it... thanks! dev= create index on table(code,row_id); CREATE INDEX Time: 38088.482 ms dev= explain (analyse,buffers) select row_id as last_row_id from table where code='XX' order by row_id desc limit 1; QUERY PLAN

Re: [PERFORM] Index Scan Backward Slow

On 01 May 2015, at 13:54, David Osborne da...@qcode.co.uk wrote: Hi, We have a query which finds the latest row_id for a particular code. We've found a backwards index scan is much slower than a forward one, to the extent that disabling indexscan altogether actually improves the query