Isolating and Tuning Problem SQL Spotlight on Oracle's Top SQL drilldown allows you to identify the SQL that is consuming the most resources on your system. Tuning this SQL can be one of the most e...
RAC uses cluster interconnects to transfer blocks between the nodes participating in the cluster. A block transfer occurs when a user session connected to one instance requests a block being held in t...
Improving Redo Log Writer Performance Redo logs contain details of transactions that may not yet have been written to the data files. The primary purpose of the redo logs is to allow for the recove...
The Parallel Query Option (PQO) is best used for systems where large, intense queries are being performed or where large amounts of data are being loaded, indexed and queried, such as in data warehous...
While you initially configure MTS in your instance parameter file, there are some changes that you can make while the instance is running. Using the ALTER SYSTEM command, you can manually adjust the n...
Just as the architecture of the database buffer cache has changed dramatically from release to release, so too have the effectiveness of the tools Oracle supplies to assist with tuning the database bu...
Because tablespaces are not unchanging objects, monitoring tablespaces is an important aspect of the DBA's monitoring responsibilities. Tablespaces are automatically defragmented by the SMON process....
Improving Database I/O A number of performance indicators can suggest a need to improve Oracle disk I/O. A major aim of configuring an Oracle server is to ensure that disk I/O does not become a bot...
The redo logs store all transactions which alter the database, all committed updates, adds, deletes of tables, structures or data. If archiving is disabled, only data in the current off-line and on-li...
DB file waits Wait conditions starting with the phrase DB FILE (for example, db file parallel write, db file scattered read, db file sequential read, and db file single write) all occur when an Ora...
Buffer busy waits Buffer busy waits occur when a session cannot access a needed block because it is in use by another session. The two most common causes are: insufficient free lists for a table...
Like tables and indexes, rollback segments may run out of space during processing and need to request additional extents. Dynamic extension can have a serious impact on performance, particularly on th...
