The Recycle Bin is a logical container that is used for dropped tables and their dependent objects. Oracle automatically preserves dropped objects in the Recycle Bin in case you need to recover them. Oracle then treats the space used by these objects as free space. The space can be reclaimed for use by other objects.
In the Explorer, you can view Recycle Bin space and objects for each database and for each tablespace. You can also view information about free space for each tablespace.
To view Recycle Bin space for a database or tablespace
In the Explorer tree-list, expand the node for the database or tablespace you are interested in.
Tip: Click on a database or tablespace name in the Explorer tree-list to display a pie chart which shows the amount of Recycled space as a percentage of total space.
To view free space for a tablespace
Tip: Click on a database or tablespace name in the Explorer tree-list to display a pie chart which shows the amount of free space as a percentage of total space.
To purge an object from the Recycle Bin
To restore a table from the Recycle Bin
To purge the Recycle Bin
Do one of the following:
Use the Reorg Need column in the Segments/Objects grid and the Datafile Map to identify objects in need of reorganization.
Reorg need is a measure of the benefit of reorganizing an object to resolve space-use problems. Benefit is the improvement in performance to be gained and wasted space to be recovered. The higher the value, the greater the benefit.
Note: Space Manager provides the best Reorg Need and Wasted space information when statistics are current in the Repository. Be sure to run the Repository Update job on regular or nightly basis (see Change Repository Update Schedule).
Use the following Explorer features to identify objects with the greatest need for reorganization.
To learn more about the reorg need value, review the following topics:
Explorer - Segments Grid
Each segment/object grid in the Explorer includes a Reorg Need column. This column provides the calculated reorg need value for each object in the grid.
To view Reorg Need column
Review the Reorg Need column to determine those segments that would benefit from reorganization. Click the column header twice to sort from highest to lowest need.
Explorer - Advanced Search
Use the Advanced Search window to search for objects based on their reorg need value. See Advanced Search for more information.
Explorer - Datafile Map
Use the Datafile Map to view segments with extents that are blocking you from resizing the datafile.
To view segments with blocking extents
Right-click a segment in the list to launch the Reorg Manager.
Reorg need is calculated based on factors that have a negative impact on database performance. These factors include wasted blocks and excessive chaining (which force Oracle to perform additional reads).
Which factors are used for an object depends on its type and whether it resides in a tablespace that is data dictionary managed or locally managed. The following factors are used for different object types:
To determine reorg need for an object, Space Manager performs the following calculations:
Each reorg need factor is multiplied by a weight. Default weights are 70% for wasted blocks and 30% for chained rows. Default weights add up to 100%.
Note: You can specify the default weight values in Tools | Options | Reorg Need. See Reorg Need Options.
All weighted values are added together to arrive at a reorg need value in the range of 1 to 100.
Note: Statistics for reorg need factors are taken from the Oracle data dictionary and DBMS_SPACE.