Configuring Performance Related Database Initialization Parameters

Tuning Integration Flows 28-5 The AWR automatically persists the cumulative and delta values for most of the statistics at all levels except the session level. This process is repeated on a regular time period and the result is called an AWR snapshot. The delta values captured by the snapshot represent the changes for each statistic over the time period. AWR supports the capture of baseline data by enabling you to specify and preserve a pair or range of AWR snapshots as a baseline. Carefully consider the time period you choose as a baseline; the baseline should be a good representation of the peak load on the system. In the future, you can compare these baselines with snapshots captured during periods of poor performance. Oracle Enterprise Manager is the recommended tool for viewing both real time data in the dynamic performance views and historical data from the AWR history tables. Enterprise manager can also be used to capture operating system and network statistical data that can be correlated with AWR data. For more information, see Oracle Database 2 Day + Performance Tuning Guide. The statistics collected and processed by AWR include: ■ Object statistics that determine both access and usage statistics of database segments ■ Time model statistics based on time usage for activities, displayed in the VSYS_ TIME_MODEL and VSESS_TIME_MODEL views ■ Some of the system and session statistics collected in the VSYSSTAT and VSESSTAT views ■ SQL statements that are producing the highest load on the system, based on criteria such as elapsed time and CPU time ■ Active Session History ASH statistics, representing the history of recent sessions activity

28.2.3 Configuring Performance Related Database Initialization Parameters

Below are the minimum basic configurations to be set for the dehydration store. Table 28–1 provides common init.ora parameters and their descriptions. Consider following these guidelines to set the database parameters. Ultimately, however, the DBA should monitor the database health and tune parameters based on the need. The values should be considered as starting values. Again these values can vary depending upon the target environments hardware and software topologies. Additional applications or processes, if any, that might run on the target environment could significantly have an impact on these properties. Further, these values must be adjusted based on the inferences made using the data collected through monitoring tools. Tip: This SHOULD be implemented in the staging and production environment. 28-6 Developers Guide for Oracle Application Integration Architecture Foundation Pack Table 28–1 Common init.ora Parameters Dehydration Store Specific Parameter Recommended Setting for Staging and Production Description shared_pool_size 800M Applicable when SGA Auto Tuning using sga_target and sga_maxsize is not being used. Consider setting MEMORY_TARGET instead of setting SGA and the PGA separately. sga_max_size 1504M The SGA_MAX_SIZE initialization parameter specifies the maximum size of the System Global Area for the lifetime of the instance. You can dynamically alter the initialization parameters affecting the size of the buffer caches, shared pool, and large pool, but only to the extent that the sum of these sizes and the sizes of the other components of the SGA fixed SGA, variable SGA, and redo log buffers does not exceed the value specified by SGA_MAX_SIZE. Ensure that you regularly monitor the buffer cache hit ratio and size the SGA so that the buffer cache has an adequate number of frames for the workload. The buffer cache hit ratio may be calculated from data in the view VSYSSTAT. Also the view VDB_ CACHE_ADVICE provides data that can be used to tune the buffer cache. Consider setting MEMORY_TARGET instead of setting SGA and the PGA separately. pga_aggregate_target 800M Specifies the target aggregate PGA memory available to all server processes attached to the instance. Starting from 11g, set MEMORY_TARGET instead of setting SGA andthe PGA separately. processes 800 Set to 800 log_buffer applicable only for 10g database 30523392 LOG_BUFFER specifies the amount of memory in bytes that Oracle uses when buffering redo entries to a redo log file. Redo log entries contain a record of the changes that have been made to the database block buffers. The LGWR process writes redo log entries from the log buffer to a redo log file The goal in sizing log_buffer is to set a value that results in the least overall amount of log-related wait events. Common wait events related to a too-small log_buffer size include high redo log space requests and a too-large log_buffer may result in high log file sync waits. db_block_size 8192 DB_BLOCK_SIZE specifies in bytes the size of Oracle database blocks. The default block size of 8K is optimal for most systems. Set this parameter at the time of database creation. Tuning Integration Flows 28-7 job_queue_processes 10 JOB_QUEUE_PROCESSES specifies the maximum number of processes that can be created for the execution of jobs. It specifies the number of job queue processes per instance UNDO_ MANAGEMENT AUTO UNDO_MANAGEMENT specifies which undo space management mode the system should use. When set to AUTO, the instance starts in automatic undo management mode. In manual undo management mode, undo space is allocated externally as rollback segments. Starting with Oracle Database 11g Release 1 11.1, the default value of the UNDO_MANAGEMENT parameter is AUTO so that automatic undo management is enabled by default. You must set the parameter to MANUAL to turn off automatic undo management, if required. open_cursors 1000 OPEN_CURSORS specifies the maximum number of open cursors handles to private SQL areas a session can have at once. You can use this parameter to prevent a session from opening an excessive number of cursors. It is important to set the value of OPEN_CURSORS high enough to prevent your application from running out of open cursors. The number varies from one application to another. Assuming that a session does not open the number of cursors specified by OPEN_CURSORS, there is no added performance impact to setting this value higher than actually needed. A value of 1000 for open_cursors is a reasonable number to start with. Sga_target 1504M Setting this parameter to a nonzero value enables Automatic Shared Memory Management. Consider using automatic memory management, both to simplify configuration and to improve performance. Consider setting MEMORY_TARGET instead of setting SGA and the PGA separately. MEMORY_TARGET 2500M MEMORY_TARGET specifies the Oracle systemwide usable memory. The database tunes memory to the MEMORY_TARGET value, reducing or enlarging the SGA and PGA as needed. MEMORY_MAX_ TARGET 3000M MEMORY_MAX_TARGET specifies the maximum value to which a DBA can set the MEMORY_TARGET initialization parameter. Table 28–1 Cont. Common init.ora Parameters Dehydration Store Specific Parameter Recommended Setting for Staging and Production Description 28-8 Developers Guide for Oracle Application Integration Architecture Foundation Pack

28.2.4 Tuning Redo Logs Location and Sizing