12 Copyright © 2004, Oracle. All rights reserved. Automatic Management

12-2 Copyright © 2004, Oracle. All rights reserved. Objectives After completing this lesson, you should be able to: Describe the various tools used to diagnose database performance issues Access the database advisors Use the SQL Tuning Advisor to improve database performance

12-3 Copyright © 2004, Oracle. All rights reserved. Oracle Wait Events A collection of wait events provides information on the sessions or processes that had to wait or must wait for different reasons. These events are listed in the V$EVENT_NAME view

12-4 Copyright © 2004, Oracle. All rights reserved. V$SGASTAT pool name bytes V$SYSSTAT statistic# name class value stat_id V$SYSTEM_EVENT event total_waits total_timeouts time_waited average_wait time_waited_micro System Statistics V$EVENT_NAME event_number event_id name parameter1 parameter2 parameter3 wait_class V$SYSTEM_WAIT_CLASS wait_class_id wait_class# wait_class total_waits time_waited

12-5 Copyright © 2004, Oracle. All rights reserved.

12-6 Copyright © 2004, Oracle. All rights reserved. Displaying Session-Related Statistics V$STATNAME statistic# name class V$SESSTAT sid statistic# value V$SESSION sid serial# username command osuser seq# event# event p1/2/3text p1/2/3 p1/2/3raw wait_class wait_time seconds_in_wait state... V$SESSION_EVENT sid event total_waits total_timeouts time_waited average_wait max_wait time_waited_micro event_id V$EVENT_NAME event# name parameter1 parameter2 parameter3

12-7 Copyright © 2004, Oracle. All rights reserved. Instance/Database V$DATABASE V$INSTANCE V$PARAMETER V$SPPARAMETER V$SYSTEM_PARAMETER V$PROCESS V$BGPROCESS V$PX_PROCESS_SYSSTAT V$SYSTEM_EVENT Troubleshooting and Tuning Views Disk V$DATAFILE V$FILESTAT V$LOG V$LOG_HISTORY V$DBFILE V$TEMPFILE V$TEMPSEG_USAGE V$SEGMENT_STATISTICS Contention V$LOCK V$UNDOSTAT V$WAITSTAT V$LATCH Memory V$BUFFER_POOL_STATISTICS V$LIBRARYCACHE V$SGAINFO V$PGASTAT

12-8 Copyright © 2004, Oracle. All rights reserved. Statistics Collection There are different types of statistics: –Optimizer statistics –System statistics There are different methods of collecting statistics: –Automatically through GATHER_STATS_JOB –Manually with the DBMS_STATS package –By setting database initialization parameters –Importing statistics from another database

12-9 Copyright © 2004, Oracle. All rights reserved. Automatic Optimizer Statistics Collection: Overview Oracle8 i Database provides DBMS_STATS package: –DBA determines how to gather statistics. –DBA determines when to gather statistics. Oracle9 i Database determines how to gather statistics: –Statistics can be gathered using a single command. –DBA determines when to gather statistics. Oracle Database 10g fully automates statistics gathering: –DBA no longer needs to gather statistics. –Table monitoring is used by default.

12-10 Copyright © 2004, Oracle. All rights reserved.

12-11 Copyright © 2004, Oracle. All rights reserved. Dictionary and Special Views The following dictionary and special views provide useful statistics after using the DBMS_STATS package: – DBA_TABLES, DBA_TAB_COLUMNS – DBA_CLUSTERS – DBA_INDEXES, INDEX_STATS – INDEX_HISTOGRAM, DBA_TAB_HISTOGRAMS This statistical information is static until you reexecute the appropriate procedures in DBMS_STATS.

12-12 Copyright © 2004, Oracle. All rights reserved. Statspack Execute statspack.snap to collect statistics. Automate the collection of statistics using the spauto.sql script. Produce a report using the spreport.sql script. Set TIMED_STATISTICS to TRUE to collect timing information.

12-13 Copyright © 2004, Oracle. All rights reserved. Workload Repository SYSAUX SGA In-memory statistics 6:00 a.m. 7:00 a.m. 8:00 a.m. Snapshot 1 Snapshot 2 Snapshot 3 Snapshot 4 9:00 a.m. 9:30 a.m. ADDM finds top problems MMON

12-14 Copyright © 2004, Oracle. All rights reserved. AWR Snapshot Baselines DBMS_WORKLOAD_REPOSITORY.CREATE_BASELINE ( - start_snap_id IN NUMBER, end_snap_id IN NUMBER, baseline_name IN VARCHAR2); Relevant period in the past

12-15 Copyright © 2004, Oracle. All rights reserved. Advisory Framework Overview ADDM SQL Tuning Advisor SQL Access Advisor Memory Space PGA Advisor SGA Segment Advisor Undo Advisor Buffer Cache Advisor Library Cache Advisor PGA

12-16 Copyright © 2004, Oracle. All rights reserved.

12-17 Copyright © 2004, Oracle. All rights reserved. Database Control and Advisors

12-18 Copyright © 2004, Oracle. All rights reserved. Typical Advisor Tuning Session Adjust task parameters. Accept results? Implement recommendations. Yes No Perform analysis. Create an advisor task.

12-19 Copyright © 2004, Oracle. All rights reserved. Manually Invoking ADDM

12-20 Copyright © 2004, Oracle. All rights reserved. Application Tuning Challenges DBA ADDM SQL Tuning Advisor High-load SQL SQL workload I can do it for you! How can I tune my high-load SQL?

12-21 Copyright © 2004, Oracle. All rights reserved. SQL Tuning Advisor Overview Add Missing Index Run Access Advisor Restructure SQL Plan Tuning (SQL Profile) Automatic Tuning Optimizer SQL Analysis Optimization Mode Access Analysis Optimization Mode Plan Tuning Optimization Mode Statistics Check Optimization Mode Detect Stale/Missing Statistics Comprehensive SQL Tuning SQL Tuning Advisor

12-22 Copyright © 2004, Oracle. All rights reserved. SQL Tuning Advisor Options and Recommendations

12-23 Copyright © 2004, Oracle. All rights reserved. Using the SQL Tuning Advisor Use the SQL Tuning Advisor to analyze SQL statements and obtain performance recommendations. Sources for SQL Tuning Advisor to analyze: –Top SQL: Analyzes the top SQL statements currently active –SQL Tuning Sets: Analyzes a set of SQL statements you provide –Snapshots: Analyzes a snapshot –Baselines: Analyzes a baseline

12-24 Copyright © 2004, Oracle. All rights reserved. Using the SQL Tuning Advisor: Example

12-25 Copyright © 2004, Oracle. All rights reserved. Using the SQL Access Advisor

12-26 Copyright © 2004, Oracle. All rights reserved. Full Notes Page

12-27 Copyright © 2004, Oracle. All rights reserved. The Undo Management Page

12-28 Copyright © 2004, Oracle. All rights reserved. Automatic Undo Retention Tuning Proactive tuning: –Undo retention is tuned for longest-running query. –Query duration information is collected every 30 seconds. Reactive tuning: –Undo retention is gradually lowered under space pressure. –Oldest unexpired extents are used first. –Undo retention never goes below either UNDO_RETENTION or 15 minutes (whichever is less). Enabled by default

12-29 Copyright © 2004, Oracle. All rights reserved. The Undo Advisor Page

12-30 Copyright © 2004, Oracle. All rights reserved. Summary In this lesson, you should have learned how to: Describe the various tools used to diagnose database performance issues Access the database advisors Use the SQL Tuning Advisor to improve database performance

12-31 Copyright © 2004, Oracle. All rights reserved. Practice 12 Overview: Optimizing Database Performance This practice covers proactively tuning your database using ADDM.

12-32 Copyright © 2004, Oracle. All rights reserved.