Identifying PID/SPID for killed session in 11g

Posted by oraclue on July 28, 2009 · 8 Comments 

Many times I  killed session with alter system kill session command ( or Toad ) and then session would just hang without dying.Then when I tried to find which OS process is related to killed session I could not identify it directly by using v$session and v$process view and joining them using addr column.According to … Read more

Filed under Troubleshooting

Oracle Linux Test (OLT) Kit

Posted by oraclue on July 28, 2009 · Leave a Comment 

Oracle Linux Tests are designed to verify Linux kernel functionality and stability essential for the Oracle Database. The OLT kit can perform different tests like installation, stress and destructive tests on virtualized and non-virtulized systems. More info at: http://oss.oracle.com/projects/olt/ Also Oracle’s  program Oracle Validated Configurations offers pre-tested and validated achitectures with documents. http://www.oracle.com/technology/tech/linux/validated-configurations/index.html

Filed under Tools

Accessing Fixed Tables using Direct Access

Posted by oraclue on July 22, 2009 · 7 Comments 

Few years ago I wrote article about direct memory access. www.petefinnigan.com/Storing_Data_Directly_From_Oracle_SGA.pdf Data are retrieved  directly from SGA.Main advantage is speed . The Oradebug utility has command called direct_accesswhich as names suggest access fixed tables directly. Help command will list all options: SQL> oradebug help direct_access DIRECT_ACCESS  <set/enable/disable command | select query> Fixed table access SQL> oradebug … Read more

Filed under Internals

Direct path reads and serial table scans in 11g

Posted by oraclue on July 17, 2009 · 10 Comments 

To answer comment by Frits about Doug Burns observation of using full table scans that resulted in direct path  reads.  Here is explanation from Oracle itself: There have been changes in 11g in the heuristics to choose between direct path reads or reads through buffer cache for serial table scans. In 10g, serial table scans … Read more

Filed under Performance

Wide Table Select ( Row Shipping )

Posted by oraclue on July 13, 2009 · 10 Comments 

In 10g Oracle  introduces a special performance feature called “row shipping” or “wide table select”.Row shipping is feature which allows row data from the datablock to be shipped directly to the client. Aperently , this feature had some issues in earlier version of 10g  and fix was to disable the “row shipping” feature by default.Oracle introduced … Read more

Filed under Internals