OCA /OCP Oracle Database 11g A ll-in-One Exam Guide- P98 pot

OCA/OCP Oracle Database 11g All-in-One Exam Guide 926 This illustration shows Step 3. 4. Connect as SYSTEM. Terminate the capture, and process it: execute dbms_workload_capture.finish_capture; execute dbms_workload_replay.process_capture('PLAY_D'); 5. Replay the workload. Note that when launching the replay client, you must specify the physical path, not the Oracle directory: exec dbms_workload_replay.initialize_replay('play capture','PLAY_D'); exec dbms_workload_replay.prepare_replay; In a separate window, launch the client from an operating system prompt: wrc player/player replaydir=/home/oracle/play_d In the SQL*Plus session, start the replay: exec dbms_workload_replay.start_replay; The illustrations show this step. Chapter 25: Performance Tuning 927 PART III 6. To retrieve the replay report, you must first obtain its ID number: select id,capture_id,directory,start_time,end_time from dba_workload_replays; Set the SQL*Plus buffer size, and retrieve the report: set long 100000 select dbms_workload_replay.report(<id>,'TEXT') from dual; Study the report, and note the values of the DB Time for the Replay and the Capture: they will be similar. 7. Connected as PLAYER, add a primary key constraint to the table: alter table t1 add constraint t1_pk primary key (object_id); 8. Repeat Steps 5 and 6. You will observe a significant drop in the DB Time value, demonstrating the improvement in performance that follows from defining the constraint. 9. Tidy up: drop user player cascade; Two-Minute Drill Use Automatic Memory Management • Automatic Shared Memory Management can be enabled with the parameter SGA_TARGET. • Automatic PGA Management can be enabled with the parameter PGA_ AGGREGATE_TARGET. • Automatic Memory Management can be enabled with the parameter MEMORY_TARGET. OCA/OCP Oracle Database 11g All-in-One Exam Guide 928 Use Memory Advisors • There are advisors for PGA, SGA, and total memory usage. • The advisors can be accessed by querying dynamic performance views, or through Enterprise Manager. Troubleshoot Invalid and Unusable Objects • Procedural objects will become invalid if the objects on which they depend are changed. • Indexes will become unusable if their table is moved. • Oracle will attempt to recompile invalid procedural object automatically. • Unusable indexes must be rebuilt manually. • Oracle will not attempt to use an unusable index, by default, so there will be no errors. Implement Automatic Memory Management • You configure AMM by setting the parameter MEMORY_TARGET. • MEMORY_MAX_TARGET is an upper bound for MEMORY_TARGET. The former is not a dynamic parameter. • When MEMORY_TARGET is set and both SGA_TARGET and PGA_ AGGREGATE_TARGET are set, then SGA_TARGET and PGA_AGGREGATE_ TARGET are used as minimum values. Manually Configure SGA Parameters • You can set MEMORY_TARGET to zero and SGA_TARGET to a nonzero value to exercise more control over SGA memory. • Adjustments to automatically tuned SGA parameters are saved across instance restarts. • ASMM uses the MMAN background process to coordinate changes in memory size. • The five auto-tuned ASMM initialization parameters are SHARED_POOL_SIZE, LARGE_POOL_SIZE, JAVA_POOL_SIZE, DB_CACHE_SIZE, and STREAMS_ POOL_SIZE. • The manually tuned ASMM initialization parameters are DB_KEEP_CACHE_ SIZE, DB_RECYCLE_CACHE_SIZE, DB_nK_CACHE_SIZE, and LOG_BUFFER. • You can easily disable ASMM by setting SGA_TARGET to zero, but then the current auto-tuned ASMM initialization parameters are set to their current values. • The static parameter SGA_MAX_SIZE is the upper limit for the value of SGA_ TARGET. Chapter 25: Performance Tuning 929 PART III Configure Automatic PGA Memory Management • The parameter PGA_AGGREGATE_TARGET sets an upper limit for memory used by all server and background processes and enables auto-tuning of PGA memory. • PGA memory areas include private SQL areas, named cursors, work areas for sorting operations, and session-specific memory variables. Use the SQL Tuning Advisor • The SQL Tuning Advisor performs statistics analysis, SQL Profile analysis, access path analysis, and structure analysis. • The SQL Tuning Advisor can automatically implement SQL Profiles. • The SQL Tuning Advisor tunes each SQL statement individually. • You can specify a SQL Tuning Set, a workload, recent SQL activity, or a single SQL statement as input to the SQL Tuning Advisor. Use the SQL Access Advisor to Tune a Workload • A SQL Access Advisor workload can consist of a single SQL statement, a SQL Tuning Set, the current SQL cache contents, existing statistics, or a schema name. • Recommendations from the SQL Access Advisor include new indexes, materialized views, and partitioning. • The four steps composing a SQL Access Advisor session are: (1) creating the task, (2) defining the workload, (3) generating the recommendations, and (4) reviewing and implementing the recommendations. • You can either review usage of existing structures or recommend new structures in a SQL Access Advisor session. Understand Database Replay • Database Replay consists of four steps: (1) workload capture, (2) workload preprocessing, (3) workload replay, and (4) analysis and reporting. • Each recorded client request contains the SQL text, bind values, and transaction information—including a timestamp. • Client requests such as SQL*Loader operations, Oracle Streams, flashback queries, distributed transactions, and remote DESCRIBE or COMMIT commands are not included in the capture operation. • Captured replay information needs to be processed only once for any number of target environments, and for any number of replays on the target system. OCA/OCP Oracle Database 11g All-in-One Exam Guide 930 Self Test 1. Where are private SQL areas stored? (Choose the best answer.) A. In each session’s PGA, always B. In each session’s PGA, unless a PGA Aggregate Target has been set C. In the PGA, unless Automatic Memory Management has been enabled D. In the shared pool of the SGA, always 2. Which memory structure is fixed in size at instance startup? (Choose the best answer.) A. The shared pool B. The large pool C. The Java pool D. The log buffer E. None are fixed, if Automatic Memory Management has been enabled 3. When Automatic Memory Management is enabled, what is not possible? (Choose the best answer.) A. Transfer of memory between sessions’ PGAs B. Transfer of memory between structures within the SGA C. Transfer of memory from SGA to PGA, and vice versa D. Increasing the total memory usage after instance startup E. All of the above are possible 4. Storage of what structures can exist in the PGA? (Choose all correct answers.) A. Shared SQL areas B. Private SQL areas C. Global temporary tables D. Sort areas E. Bitmap merge areas F. Cached object definitions 5. Which instance parameter can disable the memory advisors? (Choose the best answer.) A. DB_CACHE_ADVICE B. MEMORY_TARGET C. STATISTICS_LEVEL D. TIMED_STATISTICS Chapter 25: Performance Tuning 931 PART III 6. Which of these parameters cannot be changed without an instance restart? (Choose all correct answers.) A. MEMORY_MAX_TARGET B. MEMORY_TARGET C. PGA_AGGREGATE_TARGET D. SGA_TARGET 7. If you create a table and a procedure that refers to it, and then change the definition of the table, what will happen when you try to run the procedure? (Choose the best answer.) A. The procedure will recompile automatically and run successfully. B. The procedure will fail until you recompile it. C. The procedure will run with reduced performance until you analyze the table. D. The procedure may or may not compile, depending on the nature of the change. 8. If a SELECT statement attempts to use an UNUSABLE index, what will happen? (Choose the best answer.) A. The statement will fail. B. The statement will succeed, but at reduced performance. C. The index will be rebuilt automatically if possible. D. It depends on the SKIP_UNUSABLE_INDEXES parameter. 9. You determine that an index is unusable, and decide to rebuild it. Which of the following statements, if any, are correct? (Choose all correct answers.) A. The NOLOGGING and ONLINE keywords cannot be used together when rebuilding the index. B. A rebuild may require double the disk space while it is in progress. C. If you do not use the ONLINE keyword during a rebuild, the table will be unavailable for SELECT and DML statements. D. The NOLOGGING keyword applied to a rebuild means that DML against the index will not generate redo. 10. If a primary key index becomes unusable, what will be the effect upon an application that uses it? (Choose the best answer.) A. SELECT will succeed, but perhaps at reduced performance. B. DML commands will succeed, but perhaps at reduced performance. C. The primary key constraint can no longer be enforced. D. The table may be locked for DML. OCA/OCP Oracle Database 11g All-in-One Exam Guide 932 11. Identify the true statement about Automatic Memory Management (AMM). (Choose the best answer.) A. MEMORY_TARGET and MEMORY_MAX_TARGET must both be set to enable AMM. B. MEMORY_TARGET enables AMM, and it is a static parameter. C. MEMORY_MAX_TARGET enables AMM, and it is a static parameter. D. MEMORY_TARGET enables AMM, and it is a dynamic parameter. 12. The SQL Tuning Advisor performs all but which of the following analyses? (Choose the best answer.) A. Structure analysis B. SQL Profile analysis C. Access paths D. Changes to materialized views E. Statistics analysis 13. Which of the following can you use as input for the SQL Tuning Advisor? (Choose all that apply.) A. A single SQL statement provided by a user B. An existing SQL Tuning Set (STS) C. A preprocessed Database Replay workload D. A schema name E. A SQL statement identified in EM as using excessive resources 14. Which of the following procedures will run a SQL Tuning Advisor job against a SQL Tuning Set? (Choose the best answer.) A. DBMS_QUICKTUNE.EXECUTE_TUNING_TASK B. DBMS_SQLTUNE.EXECUTE_TUNING_TASK C. DBMS_SQLTUNE.RUN_TUNING_TASK D. DBMS_ADVISOR.EXECUTE_TUNING_TASK 15. Which of the following can you use as input for the SQL Access Advisor? (Choose all that apply.) A. A single SQL statement provided by a user B. An existing SQL Tuning Set (STS) C. A preprocessed Database Replay workload D. A schema name E. Current SQL cache contents 16. Which of the following changes can the SQL Access Advisor recommend? (Choose two answers.) A. Restructuring one or more SQL statements Chapter 25: Performance Tuning 933 PART III B. Gathering statistics for selected SQL statements C. Adding a materialized view log D. Enabling query rewrite 17. Which of the following procedures will run a SQL Access Advisor job against a single SQL statement? (Choose the best answer.) A. DBMS_QUICKTUNE.EXECUTE_TUNING_TASK B. DBMS_ADVISOR.EXECUTE_TUNING_TASK C. DBMS_SQLTUNE.RUN_TUNING_TASK D. DBMS_ADVISOR.QUICK_TUNE E. The SQL Access Advisor requires a workload, AWR snapshot, or STS and cannot analyze a single SQL statement 18. You want to remap your database links so that they do not reference production database objects. Within which Database Replay step do you perform the remapping? (Choose the best answer.) A. During the workload replay step B. During the workload preprocessing step C. During the workload capture step D. Before the workload capture starts E. You do not need to remap, since it happens automatically 19. Which of the following database client operations are captured during Database Replay? (Choose all that apply.) A. A flashback query B. Distributed transactions C. Oracle Streams operations D. A CREATE TABLE statement E. A transaction started before capturing begins Self Test Answers 1. þ A. Private SQL areas are private to each session, in the session’s PGA. ý B, C, and D. B is wrong because automatic PGA management is not relevant to where the private SQL area is stored, only to how it is managed. C and D are wrong because private SQL areas are always in the PGA. 2. þ D. The log buffer cannot be changed after startup. ý A, B, C, and E. A, B, and C are wrong because all these structures can be resized. E is wrong because not even Automatic Memory Management makes the log buffer resizable. OCA/OCP Oracle Database 11g All-in-One Exam Guide 934 3. þ E. Memory can be transferred between all structures (except the log buffer), and the total can be increased. ý A, B, C, and D. These are wrong because all are possible—though D, the increase of total memory usage, is only possible up to the value specified by the MEMORY_MAX_TARGET parameter. 4. þ B, C, D, and E. These are all PGA memory structures, though they may spill to a temporary segment in the users’ temporary tablespace. ý A and F. These are wrong because these structures both exist in the shared pool of the SGA. 5. þ C. STATISTICS_LEVEL must be on TYPICAL or FULL, or the advisors will not run. ý A, D, and B. A and D are wrong, because these parameters (which still exist only for backward compatibility) are controlled by STATISTICS_LEVEL. B is wrong because MEMORY_TARGET determines whether implementing the advice is automatic or manual. 6. þ A. MEMORY_MAX_TARGET is a static parameter: it cannot be changed without restarting the instance. ý B, C, and D. All these parameters are dynamic, meaning that they can be changed without restarting the instance. 7. þ D. Oracle will attempt recompilation, but this may not succeed. ý A, B, and C. A is wrong because this will not necessarily succeed if the nature of the change is such that the procedure needs to be rewritten. B is wrong because manual recompilation is not necessary (though it may be a good idea). C is wrong because it refers to object statistics, which are not relevant to a problem of this kind. 8. þ D. The SKIP_UNUSABLE_INDEXES parameter will control whether the statement produces an error or reverts to an alternative plan. ý A, B, and C. A and B are both wrong because they make an assumption about the SKIP_UNUSABLE_INDEXES parameter: A assumes it is false; B assumes it is true. C is wrong because indexes are never rebuilt automatically. 9. þ B. A rebuild requires additional space, as the new index is built before the original index is dropped. ý A, C, and D. A is wrong because NOLOGGING and ONLINE can be used together. C is wrong because without ONLINE the index is locked for DML, but not for SELECT. D is wrong because DML always generates redo—it is only the DDL that will not generate redo. 10. þ D. Loss of a primary key index means that DML against the constrained column(s) will be impossible. Chapter 25: Performance Tuning 935 PART III ý A, B, and C. A is wrong because this is not certain—it is dependent on the SKIP_UNUSABLE_INDEXES setting. B is wrong because DML commands will fail if they affect the constrained column(s). C is wrong because the constraint will be enforced—by locking the table. 11. þ D. MEMORY_TARGET enables AMM; it is a dynamic parameter and cannot be more than MEMORY_MAX_TARGET. ý A, B, and C. A is wrong because the MEMORY_MAX_TARGET can be left on default. B is wrong because MEMORY_TARGET is dynamic. C is wrong because while MEMORY_MAX_TARGET provides a limit for AMM, it does not enable it. 12. þ D. Only the SQL Access Advisor recommends changes to materialized views, including creating materialized view logs. ý A, B, C, and E. The SQL Tuning Advisor performs statistics analysis, SQL Profiling, access paths, and structure analysis. 13. þ A, B, and E. The SQL Tuning Advisor can use currently running SQL statements, a single statement provided by any user, an existing SQL Tuning Set, or historical SQL statements from AWR snapshots. ý C and D. C is wrong because you cannot use Database Replay workloads to specify SQL for the SQL Tuning Advisor. D is wrong because you cannot specify a schema or table names; you can only specify SQL statements. 14. þ B. DBMS_SQLTUNE.EXECUTE_TUNING_TASK runs a SQL Tuning Advisor task created with DBMS_SQLTUNE.CREATE_TUNING_TASK. ý A, C, and D. These are not valid packages or procedures. 15. þ A, B, D, and E. In addition to a single SQL statement (using QUICK_ TUNE), an existing STS, a schema name, and current SQL cache contents, the SQL Access Advisor also uses statistics to analyze overall SQL performance. ý C. C is wrong because you cannot use the captured Database Replay information as a source for the SQL Access Advisor. 16. þ C and D. The SQL Access Advisor recommends materialized views, materialized view logs, and enabling query rewrite. In addition, the SQL Access Advisor will also recommend new indexes or partitions. ý A and B. The SQL Tuning Advisor recommends SQL statement restructuring and statistics gathering, not the SQL Access Advisor. 17. þ D. DBMS_ADVISOR.QUICK_TUNE runs an analysis on a single SQL statement. You provide the name of the tuning task, which the procedure automatically creates, along with the SQL to be tuned. ý A, B, C, and E. A, B, and C are wrong because these procedures do not exist. E is wrong because the SQL Access Advisor can run an analysis on a single SQL statement, just as the SQL Tuning Advisor can. . the parameter MEMORY_TARGET. OCA/ OCP Oracle Database 11g All-in-One Exam Guide 928 Use Memory Advisors • There are advisors for PGA, SGA, and total memory usage. • The advisors can be accessed. Memory Management can be enabled with the parameter SGA_TARGET. • Automatic PGA Management can be enabled with the parameter PGA_ AGGREGATE_TARGET. • Automatic Memory Management can be enabled. during Database Replay? (Choose all that apply.) A. A flashback query B. Distributed transactions C. Oracle Streams operations D. A CREATE TABLE statement E. A transaction started before capturing