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Sizing the Buffer Cache → buffer pool is small to begin with. To use V$DB_CACHE_ADVICE, the parameter DB_CACHE_ADVICE should … use of additional buffers that contribute little or nothing to the cache hit ratio. In the example … delta of these statistics over an interval while your application is running, then use them to
Auditing in a Multi-Tier Environment → enables auditing of actions taken on behalf of the client. To do so, you use the BY proxy clause in
Controlling the Growth and Size of the Audit Trail → execution of audited statements To control the growth of the audit trail, you can use the following
Auditing Administrative Users → be fully audited. Use the AUDIT_SYS_OPERATIONS initialization parameter to specify if user SYS is … who connect as SYSDBA, Oracle recommends that DBAs rarely use this connection and only when
Configuring the Reserved Pool → Although Oracle breaks down very large requests for memory into smaller chunks, on some systems there might still be a requirement to find a contiguous chunk (for example, over 5 KB) of memory. (The default minimum reserved pool allocation is 4,400 bytes.) If there is not enough free space in the shared pool, then Oracle must search for and free enough memory to satisfy this request. This operation
Setting Auditing Options → specific statements on specific objects, such as ALTER TABLE on the emp table To use the AUDIT … statement to set statement and privilege options, you must have the AUDIT SYSTEM privilege. To use it to set … options causes all subsequent database sessions to use these options; existing sessions continue using … audit use
Keep Audited Information Manageable → minimizes the size of the audit trail. Use the following general guidelines when devising an auditing
Considering Multiple Buffer Pools → batch job only once a day). Multiple buffer pools let you address these differences. You can use a … statement to use a more selective index. If the SQL statement is tuned, you can move the large segment … for that instance. Using Multiple Buffer Pools To define a default buffer pool for an object, use
Log Buffer Statistics → $SYSSTAT. Use the following query to monitor these statistics over a period of time while your
Configuring and Using the Shared Pool and Large Pool → … Proper use and sizing of the shared pool can reduce resource consumption in at least four ways: Parse … applications use the same pool of SQL statements and dictionary resources. I/O resources are saved, because
26 Auditing Database Use → This chapter describes how to use the Oracle database server's auditing facilities, and contains
Understanding Memory Allocation Issues → Oracle stores information in memory caches and on disk. Memory access is much faster than disk access. Disk scans (physical I/O) take a significant amount of time, compared with memory access, typically in the order of 10 milliseconds. Physical I/O also increases the CPU resources required, because of the path length in device drivers and operating system event schedulers. For this reason, it is more
Sizing the Log Buffer → Applications that insert, modify, or delete large volumes of data usually need to change the default log buffer size. The log buffer is small compared with the total SGA size, and a modestly sized log buffer can significantly enhance throughput on systems that perform many updates. A reasonable first estimate for such systems is to make the log buffer 1 MB. On most systems, sizing the log buffer larger
Guidelines for Auditing Normal Database Activity → activities, use the following guidelines: Audit only pertinent actions. To avoid cluttering meaningful
What Information is Contained in the Audit Trail? → Oracle can write records to either the database audit trail, an operating system file, or both. This section describes the makeup of this audit trail information.
Interpreting and Using the Buffer Cache Advisory Statistics → basis, there might be little purpose in keeping the block in memory for very long following its use. A … are doing full table scans or operations that do not use the buffer cache. Increasing Memory … specifies the size of the default cache for the database's standard block size. To create and use
Using CURSOR_SPACE_FOR_TIME → If you have no library cache misses, then you might be able to accelerate execution calls by setting the value of the initialization parameter CURSOR_SPACE_FOR_TIME to true. This parameter specifies whether a cursor can be deallocated from the library cache to make room for a new SQL statement. CURSOR_SPACE_FOR_TIME has the following values meanings: If CURSOR_SPACE_FOR_TIME is set to false (the default),
Application Considerations → needs. Conversely, tuning the application's use of the caches can greatly reduce resource requirements … . Efficient use of the Oracle memory caches also reduces the load on related resources, such as the
Operating System Memory Use → fit into real memory. On most operating systems, paging reduces performance. Use the operating
Interpreting Shared Pool Statistics → Shared pool statistics indicate adjustments that can be made. The following sections describe some of your choices. Increasing Memory Allocation Increasing the amount of memory for the shared pool increases the amount of memory available to both the library cache and the dictionary cache. Allocating Additional Memory for the Library Cache To ensure that shared SQL areas remain in the cache after their
Protecting the Audit Trail → administrators only. To audit changes made to the database audit trail, use the following statement: AUDIT … administrator privileges, which itself has protection against unauthorized use.
Creating the Audit Trail Views → The following views (except STMT_AUDIT_OPTION_MAP ) are created by the CATALOG.SQL and CATAUDIT.SQL scripts: View Description STMT_AUDIT_OPTION_MAP Contains information about auditing option type codes. Created by the SQL.BSQ script at CREATE DATABASE time. AUDIT_ACTIONS Contains descriptions for audit trail action type codes ALL_DEF_AUDIT_OPTS Contains default object-auditing options that will be
Configuring and Using the Buffer Cache → operations that use the buffer cache, this section explains the following: Using the Buffer Cache
Guidelines for Auditing → Use the Database or Operating System Audit Trail Keep Audited Information Manageable Guidelines for
Guidelines for Auditing Suspicious Database Activity → When you audit to monitor suspicious database activity, use the following guidelines: Audit
Managing the Audit Trail → This section describes various aspects of managing audit trail information, and contains the following topics: Enabling and Disabling Auditing Setting Auditing Options Auditing in a Multi-Tier Environment Turning Off Audit Options Controlling the Growth and Size of the Audit Trail Protecting the Audit Trail
Viewing Database Audit Trail Information → available. They must be created by you. You can later delete them if you decide not to use auditing.
Buffer Pool Hit Ratios → The data in V$SYSSTAT reflects the logical and physical reads for all buffer pools within one set of statistics. To determine the hit ratio for the buffer pools individually, you must query the V$BUFFER_POOL_STATISTICS view. This view maintains statistics for each pool on the number of logical reads and writes. The buffer pool hit ratio can be determined using the following formula: hit ratio = 1
Using the Shared Pool Effectively → : Oracle9i Data Warehousing Guide In an OLTP system, there are a number of ways to ensure efficient use of … Connections Single-User Logon and Qualified Table Reference Use of PL/SQL Avoid Performing DDL Cache … Sequence Numbers Cursor Access and Management Efficient use of the shared pool in high-concurrency … parsing. Soft parses
Shared Pool Concepts → code. This is known as a soft parse, or a library cache hit. If Oracle is unable to use existing … , and comments. For example, the following statements cannot use the same shared SQL area:SELECT * FROM … only in literals cannot use the same shared SQL area. For example, the following SQL statements do not … statements must match
Fine-Grained Auditing → In the auditing methods discussed so far, a fixed set of facts is recorded in the audit trail. Additionally, audit options can only be set to monitor access of objects or privileges. No support has been discussed for obtaining more specific information about the environment or query results, nor any mechanism to specify audit conditions in order to minimize false audits. For these purposes, Oracle
Configuring and Using the Redo Log Buffer → Server processes making changes to data blocks in the buffer cache generate redo data into the log buffer. LGWR begins writing to copy entries from the redo log buffer to the online redo log if any of the following are true: The log buffer becomes one third full. LGWR is posted by a server process performing a COMMIT or ROLLBACK. DBWR posts LGWR to do so. When LGWR writes redo entries from the redo
Configuring and Using the Java Pool → If your application uses Java, you should investigate whether you need to modify the default configuration for the Java pool. See Also: Oracle9i Java Developer's Guide
Iteration During Configuration → Configuring memory allocation involves distributing available memory to Oracle memory structures, depending on the needs of the application. The distribution of memory to Oracle structures can affect the amount of physical I/O necessary for Oracle to operate. Having a good first initial memory configuration also provides an indication of whether the I/O system is effectively configured. It might be
Keeping Large Objects to Prevent Aging → loaded and aged, the free memory can become fragmented. Use the PL/SQL package DBMS_SHARED_POOL to … the loss of sequence numbers. To use the DBMS_SHARED_POOL package to pin a SQL or PL/SQL area
CURSOR_SHARING for Existing Applications → plans is outweighed by the improvements in cursor sharing. When to use CURSOR_SHARING The … were generated with CURSOR_SHARING set to EXACT. To use stored outlines with CURSOR_SHARING = FORCE or
Turning Off Audit Options → The NOAUDIT statement turns off the various audit options of Oracle. Use it to reset statement and … the scope of the statement and privilege audit options. You can use a NOAUDIT statement to disable an … this NOAUDIT statement is issued continue to use the default object audit options in effect at the
KEEP Pool → consistent gets from the older values, and use the results to compute the hit ratio. A buffer pool
Enabling and Disabling Auditing → Any authorized database user can set statement, privilege, and object auditing options at any time, but Oracle does not generate audit information for the database audit trail unless database auditing is enabled. The security administrator is normally responsible for controlling auditing. This section discusses the initialization parameters that enable and disable auditing. Note: All of the initialization
Using the Large Pool → different pool, then Oracle can use the shared pool primarily for caching shared SQL and not incur the … pools, observe UGA use for a typical user and multiply this amount by the estimated number of user … sessions. Even though use of shared memory increases with shared servers, the total amount of memory … use