SGA refers to a Shared Global Area. As the term global implies, this area is accessible to all Oracle processes and users. Each instance will have its own SGA. Oracle processes and users must share la...
Oracle9i has renamed the multi-threaded server (MTS) to shared server. The shared-server architecture increases the scalability of applications and the number of clients that can be simultaneously con...
Before implementing MTS (Multi-Threaded Server), there are several questions you need to answer: What protocols do you want to support? How many dispatchers do you want to have? How many shared se...
Oracle provides statistics which relate to the capability of rollbacks to shrink back to an optimal size. To make use of these statistics it is suggested that the following two views be created to red...
When monitoring redo logs, instead of direct views for statistics, we must look at statistics based on redo log and log writer process statistics. These views are: V$STATNAME V$SESSION V$PROCESS V$SE...
Multi-threaded server is not something that should implemented just because it exists. MTS has a specific purpose and, like any other feature, it comes with a set of trade-offs that you should conside...
CREATE REDO LOG file as part of Database >>──CREATE DATABASE database name───────────────────────────────────> v────────── , ──────────────┐ >──LOGFILE───┬───────────────┬─filespec─┴────...
Row chaining occurs when a row can't physically fit into an Oracle block. Another block is required to store the remainder of the row. Chaining can cause serious performance problems and is especially...
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...
