[jbosscache-dev] create/drop for JDBCCacheLoader

[Manik Surtani]

well the dummy table isn't really used for anything except as an  
always-positive join target (you might call it a DB-independent  
version of DUAL in Oracle).  So I don't see any problems in dropping/ 
recreating, as in the case of the actual table that holds data.

But I see your point, for the sake of consistency.  This code should  
be moved into the condition along with the data table creation code.   
Feel free to raise a JIRA/contribute a patch.  :-)

On 6 Jul 2009, at 02:31, Andrew Duckworth wrote:

> Hi Everyone,
>
> I am using the JDBCacheLoader from JBoss Cache 3.0.3 and have  
> noticed that setting the cache loader properties to prevent schema  
> update to the DB are not working as expected. I have set
>
>                cache.jdbc.table.create=false
>                cache.jdbc.table.drop=false
>
> however if appears that the jbosscache_D table is dropped and  
> recreated each time the cache loader starts. The relevant code is  
> below, can anyone comment as to whether this behaviour is  
> intentional, or should the
> createDummyTableIfNeeded method check for the table existence and  
> avoid the drop/create ?
>
> Thanks in advance,
>
> Andrew
>
>
>   public void start() throws Exception
>   {
>      cf.start();
>
>      Connection con = null;
>      Statement st = null;
>
>      try
>      {
>         con = cf.getConnection();
>         driverName = getDriverName(con);
>         if (config.getCreateTable() && ! 
> tableExists(config.getTable(), con))
>         {
>            if (getLogger().isDebugEnabled())
>            {
>               getLogger().debug("executing ddl: " +  
> config.getCreateTableDDL());
>            }
>            st = con.createStatement();
>            st.executeUpdate(config.getCreateTableDDL());
>         }
>      }
>      finally
>      {
>         safeClose(st);
>         cf.close(con);
>      }
>
>      createDummyTableIfNeeded();
>   }
>
>   private void createDummyTableIfNeeded() throws Exception
>   {
>      Connection conn = null;
>      PreparedStatement ps = null;
>      try
>      {
>         conn = cf.getConnection();
>         ps = prepareAndLogStatement(conn,  
> config.getDummyTableRemovalDDL());
>         ps.execute();
>      }
>      catch (Exception e)
>      {
>         if (getLogger().isTraceEnabled()) getLogger().trace("No need  
> to drop tables!");
>      }
>      finally
>      {
>         safeClose(ps);
>         cf.close(conn);
>      }
>
>      try
>      {
>         conn = cf.getConnection();
>         ps = prepareAndLogStatement(conn,  
> config.getDummyTableCreationDDL());
>         ps.execute();
>         safeClose(ps);
>         ps = prepareAndLogStatement(conn,  
> config.getDummyTablePopulationSql());
>         ps.execute();
>      }
>      finally
>      {
>         safeClose(ps);
>         cf.close(conn);
>      }
>   }
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--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
http://www.jbosscache.org