||Oracle Tips by Burleson
Oracle10g Grid Computing
Chapter 12 - RAC Design Considerations
Creating Efficient RAC Data Objects
shows the effects of a poor clustering factor when the data in a table
is poorly ordered, thus spreading data blocks containing
index-sequential data across multiple instances. This random
scattering of data into data blocks results in the possibility of
multiple data blocks being required by a single instance to satisfy a
range type query against a single index node. The result is the
false-pinging of data blocks between instances.
situation is desirable. Use the reverse-key index method when
multiple-instances will require access to current data referenced in
ascending numeric key or date key indexes. Use method two when data is
usually accessed by an index range scan for specific periods from the
individual instances. Method two is also good for concatenated
character-based indexes? By design, character-based indexes will
always be random (unless the table is sorted in character index
order). This is because a character-based index organizes the data
reference pointers in alphabetical order, while the data will usually
be in natural insert order, based on the mean-frequency charts for the
specific language the database uses. Character-based indexes will
always be skewed towards those letters that appear most frequently in
the leading portions of the words for a given language (in English the
letters N, R, S, L, and T lead the frequency charts).
For more information,
see the book
Grid and Real Application Clusters 30% off if you
buy it directly from Rampant TechPress .
Written by top Oracle
experts, this RAC book has a complete online code depot with
ready to use RAC scripts.
can offer world-class remote Oracle database support at super-affordable prices.
Oracle DBA service provides 100% of the remote Oracle database administration
needs for your company, and includes 24x7 access to our staff of 100% OCP
Certified Oracle DBAs.
We require a 12 month service commitment and include the following services:
- Initial configuration review and problem identification
- Installation of Oracle statistics collection mechanisms and quarterly
database growth summaries
- Hourly monitoring of your Oracle database for pending problems
- Periodic performance analysis & identification of tuning activities
- Twenty Four hour Oracle emergency support
- Reporting and resolving all serious Oracle alert log messages
- Free use of the BC
- Quick response emergency support for production database outages
- Four hours of free remote DBA support every month. You can use these free
hours for any DBA activity, including database analysis, system design,
production migrations or personal mentoring.
information, please visit www.oracle-training.cc.