October 2011 archive

Oct 12

11gR2 Compression Advisor = Evil

I recently upgraded to from Immediately after the upgrade, I noticed a spike in our redo generation. I also noticed tables with names like DBMS_TABCOMP_TEMP_UNCMP and DBMS_TABCOMP_TEMP_CMP. What are those tables doing in my production schemas and how did they get there? After digging, I was able to find out that these are …

Continue reading »

Oct 06


In the past, one would use the PCTVERSION storage parameter for their LOB segments to reserve a percentage of storage space for read consistency of LOB segments. In Oracle 11g, you can now use the RETENTION parameter. The RETENTION parameter will use the UNDO_RETENTION parameter for determining how long to keep LOB data for read-consistency …

Continue reading »

Oct 05

Upgrading Grid Control After Manual DB Upgrade

I recently went through multiple database upgrades. Some of the databases were upgraded using the DBUA utility. The DBUA utility does a nice job of modifying the database’s information in Grid Control to match the new database version. When doing the database upgrades, I also had to perform some manual upgrades. When you manually upgrade …

Continue reading »