21 November 2007

Greg Rahn Explains Plans

Greg over at Structured Data has a fantastic piece titled "Troubleshooting Bad Execution Plans" which is a must-read for all. Learning about the GATHER_PLAN_STATISTICS hint alone was worth the price of admission.

Also time for me to re-evaluate the changes I made to OPTIMIZER_INDEX_CACHING and OPTIMIZER_INDEX_COST_ADJ a few versions back:

SQL> show parameters optimizer_index


NAME                                 TYPE        VALUE
------------------------------------ ----------- -----
optimizer_index_caching              integer     90
optimizer_index_cost_adj             integer     10

Scalar::Util on CentOS5 is Bustinated

While trying to install pastebot on my CentOS5 sandbox for interal IRC usage, I found that I had to install a number of other perl modules upon which pastebot depended. This however became very frustrating as nearly all of them failed.
I ended up following the dependency chain to eventually find out that IO::Compress::Base was failing because the Scalar::Util module, installed stock by CentOS, lacked the “XS” extension. A Google search led me to this bug report confirming it. Fortunately the problem is easily solved by doing a “force install Scalar::Util” in cpan.
I assume that this problem also exists in RHEL5, and some LUGmates have reported similar breakage inFedora.

13 November 2007

Tuning Backup & Recovery

A level 0 database backup of my production instance takes over 8 hours, and duplication is just as long, if not longer. I’m going to do some reading and see if we can shore things up. I’ll report back.  The database is around 1.1 terabytes.  Some have told me that their databases of similar size are backed up in only a couple of hours.
My main concern is the duplication, or restore & recovery.  An 8 hour restore/recovery  basically means the loss of a full business day (depending on when it is needed).