2008/2/25, Pavel Rotek <pavel.rotek@gmail.com>:
> I have created functional index table(lower(href) varchar_pattern_ops)
> because of lower case "like" searching. When i ask the database directly
> from psql, it returns result in 0,5 ms, but when i put the same command via
> jdbc driver, it returns in 10 000 ms. Where can be the problem?? Any problem
> with PostgreSQL tuning??
Most likely the problem is that the JDBC driver uses prepared statements, in
which the query is planned withouth the concrete argument value. For like only
patterns that don't start with % or _ can use the index. Without the argument
value PostgreSQL can't tell whether that is the case, so it takes the safe
route and chooses a sequential scan.
to solve this particular problem, you have to convince jdbc to not use a
prepared statement for this particular query.
Markus