Friday, April 19, 2013

Streams Pool is only for Streams? Think Again!

If you don’t use the automatic SGA (i.e. set the sga_target=0) - something I frequently do - and don’t use Streams, you probably have set the parameter streams_pool_size to 0 or not set it at all, since you reckon that the pool is used for Streams alone and therefore would be irrelevant in your environment wasting memory.

But did you know that the Streams Pool is not just for Streams and it is used for other tools some of which are frequently used in almost any database environment? Take for instance, Data Pump. It uses Streams Pool, contrary to conventional wisdom. If Streams Pool is not defined, it is dynamically allocated by stealing that much memory from the buffer cache. And the size is not reset back to zero after the demand for the pool is over. You should be aware of this lesser known fact as it reduces the buffer cache you had allocated to the instance earlier.

Thursday, April 18, 2013

Application Design is the only Reason for Deadlocks? Think Again

[Updated on 4/20/2013 after feedback from Charles Hooper, Jonathan LewisLaurent Schneider and Mohamed Houri and with some minor cosmetic enhancements of outputs]

Have you ever seen a message “ORA-00060: Deadlock detected” and automatically assumed that it was an application coding issue? Well, it may not be. There are DBA-related issues and you may be surprised to find out that INSERTs may cause deadlock. Learn all the conditions that precipitate this error, how to read the "deadlock graph" to determine the cause, and most important: how to avoid it.

Tuesday, April 09, 2013

Exadata Article as NYOUG's Article of the Year 2012

The Editors of New York Oracle User Group (NYOUG) publication - TechJournal - chose my article Exadata Demystified as the Article of the Year. Here is the snippet from the Editorial:

Friday, April 05, 2013

Switching Back to Regular Listener Log Format

Did you ever miss the older listener log file format and want to turn off the ADR-style log introduced in 11g? Well, it's really very simple.