AWR In-depth analysis (Automatic workload Repository) _oracle

Automatic Workload Repositoryis an important component of 10g introduction
Storage of the recent period of time the status of the database activity details, information retention default is 7Days
The predecessor of AWR is Statspack, and Statspack is the source of the public.

Therefore, the information about Statspack, as well as the source code of Statspack, is a useful aid to understand awr.

The AWR, who areSYSOwnership, granularity is snapshot, stored inSysauxTable space is also

What is a snapshot?

Snapshots are a set of performance statistics captured and stored in AWR at specific times
Snapshot used to calculate the rate of change for statistics

How do I identify a snapshot?

Each snapshot is identified with a snapshot sequence number (snap_id), which is unique in AWR

How do I modify a snapshot?

By default, snapshots each A minutes generated once
You can adjust this frequency by changing the snapshot INTERVAL parameter
However, adjustment interval settings may affect diagnostic accuracy
For example, if you set the INTERVAL to 4 hours, you may miss spikes that occur in the 60-minute interval
With Dbms_workload_repository. Modify_snapshot_settings stored procedure or Database control to change settings for controlling snapshot collection
In the Database control:
"Administration" → "Statistics Management" → "Automatic workload Repository" → "Edit"

How do I create a snapshot?

Use Database control or dbms_workload_repository. Create_snapshot
Supports system-generated automatic snapshots while supporting manual capture of snapshots
You need to use a manual snapshot if you want to capture system behavior at two specific points of time that are inconsistent with the automatic plan

      What is a baseline?

     baseline, in short, reference standard
      A snapshot set is defined as a pair of snapshots, each baseline corresponds to a pair (and only one pair) of snapshots
      baseline is used to keep the snapshot data, therefore, snapshots that belong to the baseline remain

    until the baseline is deleted   How does identify a baseline?

      baselines can be identified either by user-supplied names or by system-generated identifiers
      Baseline identifiers are unique in the lifecycle of the database

      How do I create a baseline?

      use Database control or execute dbms_workload_repository. CREATE_BASELINE&NBSP

      When would you create a baseline?

      Typically, you set the snapshot set in some typical time periods in the past to compare to the current system behavior

     
      AWR reports that all data originates from AWR view, that is, dba_hist_ All system tables at the beginning
      How to effectively analyze AWR reports, which may require DBA experience over the longer period