Sluggish performance - queries Initializing

[Paul F]

Hi there..We recently moved our Oracle DB to an 11g 2 node RAC. We were previously on the same configuration, but just moved to new hardware in a different location. We've never had problems with PLSQL Developer before, but now we are seeing sluggish performance. Most notably is that queries are 'Initializing' for up to 90 seconds before executing. I've looked at other posts here related to this problem but I'm still not sure what it could be. I have 'Dual Sessions' in my preferences. I've included a snippet from the debugsql here (you can see this one takes 93 seconds to initialize). Any advice?
Paul.

debugsql:

4/9/2010 2:17:04 PM SQLForm Initializing...
4/9/2010 2:17:04 PM SetConnected starts
4/9/2010 2:17:04 PM Already connected: check connection
4/9/2010 2:17:04 PM TOracleQuery $030D1210 Start Query.Execute
SQL = select 'x' from dual
4/9/2010 2:18:38 PM TOracleQuery $030D1210 End (1 record processed)
Duration = 93.75
4/9/2010 2:18:38 PM Using existing connection
4/9/2010 2:18:38 PM EnableOutput starts

 

[Marco Kalter]

What is happening here is that the SQL Window checks if the secondary session (you are using dual session mode) is still alive. It does so by executing a simple "select 'x' from dual" query. This query succeeds ("1 record processed"), but takes 93.75 seconds.

This is of course much too slow. Perhaps a DBA can check why this query takes so long?

 

[Paul F]

Thanks Marco. I have been working with our DBAs. One suggestion was to remove (SERVER=SHARED) in our tnsnames.ora so it defaults to DEDICATED (or change the entry to SERVER=DEDICATED). Not sure this is helping a lot. The other thing they may try is to define more dispatchers and allowed connections in the system parameters. We'll see if this helps.