Use log_duration in postgresql.conf to log long queries, explain ANALYZE them to find out what they're doing. Sometimes a full table sequential scan is faster t

Use log_duration in postgresql.conf to log long queries, explain ANALYZE them to find out what they're doing. Sometimes a full table sequential scan is faster than using an index -- e.g. if the index would (according to gathered statistics data) hit 90% of the table anyway. There are also various other gathered statistics you can look at, e.g. cache hits, index hits etc.