An Oracle session logs the db file sequential read wait event when it has to wait for a single-block I/O read request to complete. Oracle issues single-block I/O read requests when reading from indexe...
A Rollback Segment records the old values of data that were changed by each transaction, whether committed or not. The information in a rollback segment is used to: Generate read-consistent database ...
The db file scattered read wait event is similar to the db file sequential read, except that the session is waiting for a multi-block I/O read request to complete. The db file scattered read waits are...
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...
A sort area in memory is used to sort records before they are written out to disk. Increasing the size of this memory by increasing the value of the initialization parameters SORT_AREA_SIZE or PGA_AGG...
Tuning Your Database Spotlight on Oracle supports an approach to Oracle performance tuning that could be described as "tuning by bottleneck". Spotlight on Oracle alerts you if any component of the ...
The ARRAYSIZE parameter controls the number of rows that can be returned from disk in a single network transfer. If you set ARRAYSIZE correctly, you can substantially reduce the number of network pack...
An event can be defined as a particular function, or a task, that the Oracle kernel performs on behalf of the user session or its own background process. Tasks such as reading and writing data blocks ...
This topic summarizes hints for tuning different components of your parallel server database. Data Separation Follow these rules for separating data: If at all possible, ensure that database instanc...
How to Identify a Buffer Cache Chain Latch Problem Internally, Oracle uses various types of structures to control access to elements of the databases including latches and various types of enqueuein...
Reducing lock contention Lock, or enqueue waits occur when a session waits to obtain a lock. In most cases, this occurs because of a lock on a table or row that the session wants to lock or modify....
Analyzing the Execution Plan When examining an execution plan, look for inefficiencies and opportunities to improve performance. When you see any of the following, you have an opportunity to tune the ...
