Oracle Database 11g P2

One of the important new features of the Oracle 11g database is the new DDL locking durationcontrol feature. The ddl_lock_timeout parameter lets you specify the length of time a DDLstatement will wait for a DML lock. This feature comes in handy when you want to performonline reorganization, where a DML lock by a user may prevent a DDL operation from succeeding.
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Oracle Database 11g P2 C HA PTER 1 ■ INS TA LLIN G, UPGRADING, A ND MA NAGING CHANGE 11that involve tables and views for which you have set the result_cache option. You can also cachePL/SQL function results in addition to SQL query results. In addition to the result_cache_modeoption, there are several result cache–related initialization parameters, such as the result_cache_max_result, result_cache_max_size, and result_cache_remote_expiration parameters.You can also cache query results on the client side. When you use client-side query caching,you can specify the new parameters client_result_cache_size and client_result_cache_lag.We discuss all these new parameters as part of the result cache feature in Chapter 4.■Note When you set the compatible parameter to 11.0.0 or greater, the server parameter file is written ina new format to comply with Oracle’s HARD initiative, which helps prevent writing corrupted data to disk.Parameter to Control DDL Lock TimeoutOne of the important new features of the Oracle 11g database is the new DDL locking durationcontrol feature. The ddl_lock_timeout parameter lets you specify the length of time a DDLstatement will wait for a DML lock. This feature comes in handy when you want to performonline reorganization, where a DML lock by a user may prevent a DDL operation from succeeding.You can practically specify that a DDL statement wait forever by setting the parameter to themaximum allowed value, which is 1,000,000 seconds. We discuss the ddl_lock_timeout parameterin detail in Chapter 3.SecureFiles-Related ParameterThe new Oracle SecureFiles feature is a major revamping of the implementation of Large Objects(LOBs). By using the new initialization parameter db_securefile, you can specify whether totreat a LOB file as a SecureFiles file. Please see Chapter 12 for a detailed discussion of SecureFiles.■Note The job_queue_processes parameter has been moved to the basic initialization parameters listin Oracle Database 11g. Although this is not a big deal on the face of it, the point is that Oracle is saying youdon’t have to worry about setting a value for the job_queue_processes parameter in most cases, since it’sclassified as a basic initialization parameter. The job_queue_processes parameter can take a value from0 to 1000. If you set it to 0, you can run DBMS_SCHEDULER jobs, but not the DBMS_JOB-based jobs. If you setthe parameter to any value from 1 to 1000, both DBMS_JOB-based and DBMS_SCHEDULER-based jobs will run.The db_ultra_safe ParameterThe new parameter db_ultra_safe sets default values for parameters, such as the db_block_checking parameter, that control protection levels. To be precise, you can control three corruption-checking parameters—db_block_checking, db_block_checksum, and db_lost_write_protect—byspecifying values for the db_ultra_safe parameter.12 CH APT ER 1 ■ I NST ALLI NG, U PGRA D ING , AN D M ANA GI NG CH A NGE The db_ultra_safe_parameter can take three values—off, data only, and data and index. By default, the db_ultra_safe parameter is set to off, meaning that any values you set for any of the three parameters won’t be overridden. If you set the db_ultra_safe parameter value to data only, the following will be true: • db_block_checking will be set to medium. • db_lost_write_protect will be set to typical. • db_block_checksum will be set to full. If you set the db_ultra_safe parameter value to data and index, the following will be true: • db_block_checking will be set to full. • db_lost_write_protect will be set to typical. • db_block_checksum will be set to full. Security-Related Parameters There are two important security-related initialization parameters that are new in Oracle Database 11g. The first parameter, sec_case_sensitive_logon, lets you enable and disable password case-sensitivity in the database. By default, password case-sensitivity is enabled in Oracle Database 11g. The other new security-related initialization parameter is the parameter sec_max_failed_ login_attempts, which specifies the maximum number of times a client can make a connec- tion attempt to a server. The default value of this parameter is 10. Please see Chapter 5 for more details about the new case-sensitive password feature as well as the sec_max_failed_login_attempts parameter. Optimizer-Related Parameters There are several important new optimizer-related initialization parameters that are intended to support powerful new features such as SQL Plan Management, private statistics, and invis- ible indexes. We discuss all these features in subsequent chapters and merely introduce the relevant new initialization parameters in this section. Oracle Database 11g replaces the old plan stability feature with the new SQL Plan Manage- ment feature. A change in the execution plan of an important SQL statement can potentially degrade performance. To avoid this performance degradation, the database selects optimal SQL plan baselines and prevents the optimizer from changing the execution plan of a state- ment until the new plan is found to be definitely superior to the existing SQL baseline plan (lower cost). You can enable automatic SQL plan capture so the database can capture and maintain SQL plan history using information from the optimizer. By default, automatic plan capture is disabled, and you can enable it by setting the optimizer_capture_sql_plan_baselines parameter to true. Chapter 4 contains a detailed discussion of the SQL Plan Management feature. C HA PTER 1 ■ INS TA LLIN G, UPGRADING, A ND MA NAGING CHANGE 13 Use the new initializat ...