Rollback Page
Within Oracle, rollback is the undoing of uncommitted transactions. Data that has been changed within the transaction is restored to its previous values — values that have been stored in the database in rollback segments.
The Rollback page shows information about rollback segments, including their status and optimal settings, and the number of active transactions in rollback segments.
To open the Rollback page
- Select the Spotlight on Oracle connection in the Spotlight Browser.
-
Click Activity | Rollback.
Grid on the Rollback Page
Rollback Activity (UNDO statistics) contains a description of the UNDO statistics available for rollback segments. This occurs when Spotlight is diagnosing an Oracle system where Oracle parameter "undo_management" is set to "auto".
The table shows statistics that have been collected by Oracle at 10-minute intervals.
Note: Not all columns are visible by default. Use the Column Organizer to view hidden columns. Show, Hide & Order Columns
| Column | Description |
|---|---|
|
Begin time |
The date and time at which the (10-minute) interval began. |
|
End time |
The date and time at which the interval ended. |
|
Name |
The last active UNDO tablespace name used during the time interval. |
|
Used blocks |
The total number of UNDO blocks used during the interval. |
|
Transactions |
The total number of transactions that occurred during the interval. |
|
Longest query |
The number of seconds for which the longest completed query ran during this interval. This query may also have started in the previous interval. |
|
Highest concurrent transactions |
The highest number of concurrently running transactions in this interval. |
|
Unexpired block steals |
The number of attempts to get more space by stealing unexpired extents from other transactions. |
|
Unexpired blocks removed |
The number of blocks removed during "Unexpired block steals". |
|
Unexpired blocks reused |
The number of blocks reused during "Unexpired block steals". |
|
Expired block steals |
The number of attempts to get more space by stealing expired extents from other transactions. |
|
Expired blocks removed |
The number of blocks removed during "Expired block steals". |
|
Expired blocks reused |
The number of blocks reused during "Expired block steals". |
|
Increase undo_retention? |
This column shows if you need to increase the parameter undo_retention to avoid the "ora_01555 – snapshot too old" error message. If yes, the number in parentheses shows how many times this error message occurred during the interval. |
|
Need more space? |
This column shows if you need more space in the UNDO tablespace. If yes, the number in parentheses shows how many times UNDO space ran out during this interval. |
Chart on the Rollback Page
Rollback Information (Undo activity) contains a series of graphs based on the data shown in the Rollback Activity table above, where Spotlight is diagnosing an Oracle system whose undo_management parameter is set to "auto".
| Data Series | Description |
|---|---|
|
Used blocks |
The number of UNDO blocks used during the display period. |
|
Transactions |
The number of transactions that occurred at different times during the display period. |
|
Highest concurrent transactions |
The highest number of concurrently running transactions during the displayed period of time. |
|
Longest query |
The number of seconds for which the longest completed query ran during the display period. |
Viewing individual series in the chart
The automatic scaling of this chart can sometimes make an individual graph in the chart too small to read. You can adjust the chart to display a graph to a convenient scale by temporarily removing all other graphs from the chart. To do this:
- Right-click on the header of the Rollback Activity table and select Organize columns.
- Move one or more of the items Longest query, Highest conc. txns, Used blocks, or Transactions from the list of selected columns to the list of available columns to hide its column from the table AND remove its graph from the UNDO Activity chart.
- The scaling of the chart adjusts automatically to fit the remaining graph(s) in the chart.
You can reinstate a removed graph by using Organize columns... to restore its item to the table and chart.