Recommendations Create a minimum of three groups with two log files each. A minimum of two groups of log files each are required for each Oracle instance (even in a parallel instance environment.) I...
Redo logs cannot be altered, they can only be created via the CREATE DATABASE and ALTER DATABASE commands or dropped via the ALTER DATABASE command. You can force a log switch or checkpoint if needed...
What is a Redo Log Buffer? The redo log buffer is a part of the Shared Global Area (SGA). This shared memory structure holds information about changes made to the database, called redo. Redo is genera...
Identify Contention The following query determines the miss ratio and the "immediate" miss ratio for redo log latches. Col MISS_RATIO format 999.99Col IMM_MISS_RATIO format 999.99 SELECT substr(ln.na...
In this section, we will write an application that issues the same SQL statement over and over again. The first run of the application will not use bind variables. The second run of the application wi...
The most likely problems that you will experience with replication are those with job queues. This topic addresses the following areas associated with running replication jobs: Detecting a Problem w...
Tablespaces are used to store database objects that take up space on disks. These objects are called segments. Examples of segments include tables, indexes, clusters, undo segments, and materialized v...
Library cache latches The library cache latches protect the cached SQL statements and object definitions held in the library cache within the shared pool. The library cache latch must be obtained ...
What is the Redo Copy Latch? The redo copy latch is needed to copy a redo entry into the log buffer. The redo copy latches are used to indicate that a process is copying redo into the log buffer, and ...
Starting from Oracle10g, most of the RAC related wait events could be further classified in two types, namely 'place holder' events and 'fix up events'. For example, when a cr request is initiated, th...
When you want to retrieve data from the database, the fastest way to do this is if the data the query returns is already located in memory, or cache. If it is not located in cache, then the server pro...
Enabling Direct I/O Oracle provides a number of different ways of ensuring the performance of I/O write requests is optimal, including the use of direct I/O and asynchronous I/O (see below for more de...
