My program has an issue with Oracle query performance, I believe the SQL have good performance, because it returns quickly in SQLPlus. But when my program has been running for a long time, like 1 week, the SQL query (using JDBC) becomes slower (In my logs, the query time is much longer than when I originally started the program). When I restart my program, the query performance comes back to normal. I think it is could be something wrong with the way I use the preparedStatement, because the SQL I'm using does not use placeholders "?" at all. Just a complex select query. The query process is done by a util class. Here is the pertinent code building the query: public List<String[]> query(String sql, String[] args) { Connection conn = null; conn = openConnection(); conn.setAutocommit(true); .... PreparedStatement preStatm = null; ResultSet rs = null; ....//set preparedstatment arg code rs = preStatm.executeQuery(); .... finally{ //close rs //close prestatm //close connection } } In my case, the args is always null, so it just passes a query sql to this query method. Is that possible this way could slow down the DB query after program long time running? Or I should use statement instead, or just pass args with "?" in the SQL? How can I find out the root cause for my issue? Thanks.