学步园

Connection conn = null;<br /> ResultSet rs = null;<br /> PreparedStatement stmt = null;<br /> try<br /> {<br /> conn = dbMgr.getConnection();<br /> stmt = conn.prepareStatement(track_sql);<br /> rs = dbMgr.executeQuery(conn, stmt);</p> <p> while (rs.next())<br /> {<br /> ret.add(rs.getLong(1));<br /> }<br /> } finally<br /> {<br /> if (stmt != null)<br /> stmt.close();<br /> if (rs != null)<br /> rs.close();<br /> if (conn != null)<br /> dbMgr.releaseConnection(conn);<br /> } 

When testing in Oracle, above loop is very slow. If add setFetchSize before next,  the performance improve significantly 

rs.setFetchSize(DbMgr.FETCH_SIZE_LARGE_ROW); 

ResultSet interface also provides batch retrieval facility like Statement as mentioned above. It overrides the Statement behaviour.

Initially find the default size by using

ResultSet.getFetchSize(); and then set the size as per requirement

ResultSet.setFetchSize(50);

This feature significantly improves performance when you are dealing with retrieval of large number of rows like search functionality.

TODO: reading full tips

http://www.precisejava.com/javaperf/j2ee/JDBC.htm#JDBC114