Auto Workload Repository-Imtiyaz Presentation

8/2/2019 Auto Workload Repository-Imtiyaz Presentation

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Imtiyaz Shaikh


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Until Oracle 9i, DBAs spent a lot of time on databasemonitoring, identifying problem areas and performancebottlenecks

DBA tasks focused on System Resources

Storage management

Space Management

Application and SQL tuning

Fixing Security Issues


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AWR, a built-in repository in every database is thecentral component of Oracle Database 10gmanageability infrastructure.

Provides services to the database to access, collect,

process, and maintain performance statistics on variousfunctionalities within the database.

At regular intervals (60 minutes), Oracle Database 10gtakes snapshots of all vital statistics and workload data

Stores them in the repository for a period of seven days.


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The repository is a source of information forseveral other Oracle 10g features including:

Automatic Database Diagnostic Monitor

SQL Tuning AdvisorUndo Advisor

Segment Advisor


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Repository data used for analysis and as statistics for

problem detection and self-tuning.

Used for system level and user level analysis.

AWR is the basis for all self-management functionalitiesof the database.

Gives the Oracle Database with the historicalperspective on its usage.

AWR has report generation mechanism to producesummary reports based on database statistics.

Very similar to STATSPACK in previous database

versions, but a lot convenient to use


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AWR in Oracle Database 10g collects-

Time model statistics

Object statistics

Session and system statistics in v$sesstat andv$sysstat

Optimizer statistics


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Active Session History (ASH) contains recent sessionactivity.

Memory for ASH comes from the SGA, fixed for theinstance lifetime.

ASH samples the v$sessionview every second andrecords the events the active sessions are waiting for.

ASH statistics can be viewed fromv$active_session_history, one row for each active

session per sample with the latest session rows first. Contents of v$active_session_history flushed to disk

as part of the AWR snapshot process.


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AWR stored in Workload Repository (WR) schema. AWR schema resides in the SYSAUX tablespace. A snapshot is a set of performance statistics captured

at a certain time in the database. Used for computing the rate of change of a statistic. Identified by unique snapshot sequence # (snap_id). Generated every 60 minutes by default. INTERVAL parameter to change snapshot frequency.

Manual snapshots can be taken using the

DBMS_WORKLOAD_REPOSITORY.CREATE_SNAPSHOT procedure or through Enterprise Manager.


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Metrics are a set of statistics for certain systemattributes.

Calculated and stored by the Automatic WorkloadRepository (AWR).

Results displayed in Enterprise Manager through theAll Metricspage under Related Linkson theDatabase Homepage.

Thresholds are the boundary values against

which the metric values are compared.


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AWR reports are generated using awrrpt.sql, awrrpti.sql,awrddrpt.sql, and awrddrpi.sqlin$ORACLE_HOME/rdbms/admindirectory.

Reports as html pages or text reports. awrrpt.sql - all available AWR snapshots.

awrrpti.sql - statistics for a range of snapshot ids on aspecified database and instance awrddrpt.sql - statistics of a particular SQL statement

for a range of snapshot ids. awrddrpi.sql - statistics of a SQL statement for a range

of snapshot ids on a specified database and instance.


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Thank You

Auto Workload Repository-Imtiyaz Presentation

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