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Database Feed

Oracle Database, Oracle 10g, Oracle 11g, Oracle XE, Oracle RAC, Oracle Instant Client, Oracle Data Guard and Oracle Exadata resources, news, and support articles.

Beware of Deferred Segment during 11.2.0.2 upgrade from 11.2.0.1

We recently upgraded one of our biggest databases to 11.2.0.2 from 11.2.0.1 due to the library cache mutex related bugs on 11.2.0.1. Since I wasn’t the one who did the upgrade I have nothing to say about the process but I was the on call DBA on the next day after the upgrade.

Users started to report the ORA-00600 for the statement below

Ignoring hints

Yes, finally, really ignoring hints – but it’s a sort of bug, of course. Thanks to Timur Akhmadeev for telling us about bug 8432870 (you’ll need an account on MOS for the link) in his reply to Charles Hooper’s recent post. In the upgrade from 9i to 10g there was a change in the “hint [...]

Time Flies

I recently got an email from Iggy Fernandez, current president of the Northern California Oracle User Group. He was asking if I could contribute a short note to his “Ask the Oracles” series – but he also mentioned that the journal is entering its 25th year (hence the title of the piece) and the group [...]

ORA-14452: attempt to create, alter or drop an index on temporary table already in use

After reading Hemant Sir’s blog “GLOBAL TEMPORARY TABLEs and GATHER_TABLE_STATS ” (http://hemantoracledba.blogspot.com/2011/01/global-temporary-tables-and.html) i tried the same on my system and again learned something new Time to share it .

Hash Aggregation

Oracle introduced in Oracle 10g the hash aggregation as a new feature.

UKOUG TechEBS 2010 - Conference Thoughts

I wish I could say I planned to break the all-time record for post-conference blogging delay and was waiting until Debra Lilley got round to hers, but the truth is this is yet another post that slipped through the cracks in the constant work/play/travel continuum.

Adding Comments to SQL Statements Improves Performance?

January 15, 2011 While reading the “Pro Oracle SQL” book I learned something interesting.  Commenting your work can improve database performance.  You certainly are aware that thoroughly documenting what you do could prevent hours of headaches that might appear later when trying to investigate problems or add additional features to an existing procedure (I think that was [...]

ORA-00214 and Control File Mismatch

One of the many reasons, as why a clean Oracle database shutdown should always be a 'must' ingredient of server reboot SOP, is ORA-214.

The scenario goes like this:

The instance was in nomount stage and was unable to mount the database.
First checked the uptime, and it was found that the server was rebooted some 5 minutes ago, and instance tried to come up automatically but failed to mount the database.
Checked the alert log and found the following error:

ORA-214 signaled during: ALTER DATABASE   MOUNT...

Myth breaker: Patching Exadata

Exadata Storage Software has become a powerfull extension of the Oracle Database, not only leveraging performance but also offloading tasks from the database server, off to the storage server. The span of this relationship is more visible when you have … Continue reading

GLOBAL TEMPORARY TABLEs and GATHER_TABLE_STATS

If you use a Global Temporary Table in your application code, watch where and how you run GATHER_TABLE_STATS on it.
(I prefer to NOT have statistics on a GTT and to delete statistics if present ; so that Oracle can do Dynamic Sampling against the table when using it in a query).

If your GTT has been defined as ON COMMIT DELETE ROWS, the GATHER_TABLE_STATS call will result in rows being deleted. This is because the GATHER_TABLE_STATS issues an implicit commit.

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