db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Kathey Marsden (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6053) Client should use a prepared statement rather than regular statement for Connection.setTransactionIsolation
Date Mon, 04 Feb 2013 18:46:17 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6053?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13570499#comment-13570499
] 

Kathey Marsden commented on DERBY-6053:
---------------------------------------

Thanks Mamta for the patch.

Do you get the same warning with tis patch and the more strongly typed iterator?

The patch looks good to me.  A couple minor points.
Since this catch block might be for more than one prepared statement close, it should probably
only set accumulateExceptions to se if accumulatedExceptions is null, otherwise do accumulatedExceptions.setNextException(se)

               } catch (SQLException se) {
                    accumulatedExceptions = se;
                }

There are  tabs mixed in with the spaces even on lines that have otherwise not changed.  The
client code should be all space indentation.




 
                
> Client should use a prepared statement rather than regular statement for Connection.setTransactionIsolation
> -----------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-6053
>                 URL: https://issues.apache.org/jira/browse/DERBY-6053
>             Project: Derby
>          Issue Type: Improvement
>          Components: Network Client
>            Reporter: Kathey Marsden
>         Attachments: DERBY6053_patch1_diff.txt
>
>
> o.a.d.client.am.Connection setTransactionIsolation() uses a Statement which  it builds
up each time for setTransactionIsolation()  is called.
> private Statement setTransactionIsolationStmt = null;
> ...
> setTransactionIsolationStmt =
>                     createStatementX(java.sql.ResultSet.TYPE_FORWARD_ONLY,
>                             java.sql.ResultSet.CONCUR_READ_ONLY,
>                             holdability());
> ....
>  private void setTransactionIsolationX(int level)
> ...
>             setTransactionIsolationStmt.executeUpdate(
>                 "SET CURRENT ISOLATION = " + levelString);
> It would be better for performance and also for avoid possible garbage collection issues,
to have a single prepared statement with a parameter marker. 
> The program below shows repeated calls to setTransactionIsolation.
> import java.sql.*;
> import java.net.*;
> import java.io.*;
> import org.apache.derby.drda.NetworkServerControl;
> /**
>  * Client template starts its own NetworkServer and runs some SQL against it.
>  * The SQL or JDBC API calls can be modified to reproduce issues
>  * 
>  */public class SetTransactionIsolation {
>     public static Statement s;
>     
>     public static void main(String[] args) throws Exception {
>         try {
>             // Load the driver. Not needed for network server.
>             
>             Class.forName("org.apache.derby.jdbc.ClientDriver");
>             // Start Network Server
>             startNetworkServer();
>             // If connecting to a customer database. Change the URL
>             Connection conn = DriverManager
>                     .getConnection("jdbc:derby://localhost:1527/wombat;create=true");
>             // clean up from a previous run
>             s = conn.createStatement();
>             try {
>                 s.executeUpdate("DROP TABLE T");
>             } catch (SQLException se) {
>                 if (!se.getSQLState().equals("42Y55"))
>                     throw se;
>             }
>             for (int i = 0; i < 50000; i++) {
> 		conn.setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ);
> 		conn.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);
> 	    }
>             
>             // rs.close();
>             // ps.close();
>             runtimeInfo();
>             conn.close();
>             // Shutdown the server
>             shutdownServer();
>         } catch (SQLException se) {
>             while (se != null) {
>                 System.out.println("SQLState=" + se.getSQLState()
>                         + se.getMessage());
>                 se.printStackTrace();
>                 se = se.getNextException();
>             }
>         }
>     }
>     
>     /**
>      * starts the Network server
>      * 
>      */
>     public static void startNetworkServer() throws SQLException {
>         Exception failException = null;
>         try {
>             
>             NetworkServerControl networkServer = new NetworkServerControl(
>                     InetAddress.getByName("localhost"), 1527);
>             
>             networkServer.start(new PrintWriter(System.out));
>             
>             // Wait for the network server to start
>             boolean started = false;
>             int retries = 10; // Max retries = max seconds to wait
>             
>             while (!started && retries > 0) {
>                 try {
>                     // Sleep 1 second and then ping the network server
>                     Thread.sleep(1000);
>                     networkServer.ping();
>                     
>                     // If ping does not throw an exception the server has
>                     // started
>                     started = true;
>                 } catch (Exception e) {
>                     retries--;
>                     failException = e;
>                 }
>                 
>             }
>             
>             // Check if we got a reply on ping
>             if (!started) {
>                 throw failException;
>             }
>         } catch (Exception e) {
>             SQLException se = new SQLException("Error starting network  server");
>             se.initCause(failException);
>             throw se;
>         }
>     }
>     
>     public static void shutdownServer() throws Exception {
>         NetworkServerControl networkServer = new NetworkServerControl(
>                 InetAddress.getByName("localhost"), 1527);
>         networkServer.shutdown();
>     }
>     
>     public static void runtimeInfo() throws Exception {
>         NetworkServerControl networkServer = new NetworkServerControl(
>                 InetAddress.getByName("localhost"), 1527);
>         System.out.println(networkServer.getRuntimeInfo());
>     }
>     
> }

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message