Oracle Enterprise Manager Database Tuning with the Oracle Tuning Pack
Release 9.0.1

Part Number A86647-01

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24
Introduction to the Tablespace Map

The Tablespace Map provides a complete picture of the characteristics of all tablespaces associated with a particular Oracle database. These characteristics include analysis status, segment type, segment name, number of extents, and the total size of the extent in blocks. You can display all segments for a tablespace.

The Tablespace Map also provides an allocation map which illustrates the organization of a tablespace's segments. This map displays an overview of the sequential allocation of space for segment extents within a selected tablespace. Within the tablespace map, it is possible to point to an individual extent and see the following detail information:

Another key feature of the Tablespace Map is the Tablespace Analysis tool. A tablespace analysis can detect potential space management problems. Once a tablespace analysis has been performed, a Tablespace Analysis report is created and provides a detailed listing of any detected problems and marks the problematic segments with a warning or alert flag. See Analyzing Segments in a Tablespace.


Note:

You can print the current tablespace extent map by selecting File=>Print=>Tablespace Summary and Map from the menu bar. When you print the extent map, a list of the segments that make up the tablespace will also be provided. 


Accessing the Tablespace Map

The Tablespace Map is part of the Oracle Tuning Pack. When the Tuning Pack is installed, you can access the Tablespace Map from the Oracle Enterprise Manager console. The Tablespace Map is always launched in context to a selected tablespace.

Viewing the Tablespace Map

The Tablespace Map provides a list of all of the segments for a selected tablespace and a graphical display of the extents that make up those segments.


Note:

The first time you use Tablespace Map, gray flags will appear in the Analysis column of the Segment List which indicates that the segments have not been checked for space usage problems. Select Tablespace Analysis from the Tools menu to perform the analysis. The results of the Tablespace Analysis appear in the Tablespace Analysis Report tab. You can also print the Tablespace Analysis report by using the File=>Print=>Tablespace Analysis Report menu item. 


The list of segments includes the following information:

The graphical display shows how space is being used within the tablespace:

Figure 24-1 Tablespace Map


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Analyzing Segments in a Tablespace

The Tablespace Analysis tool checks the tablespace for various space usage problems such as objects suffering from excessive row chaining and/or migration and overextended objects. The tool also generates a full report that describes all of the space usage problems in the current tablespace. The report can be printed and used in conjunction with the Reorg Wizard to correct the problems.

Generating a Tablespace Analysis Report

To run the Tablespace Analysis, use the Tools=>Tablespace Analysis menu item or the Tablespace Analysis tool bar button. The Analysis is performed immediately. The results are displayed in the form of colored flags in the Analysis column of the Segment List. The colored flags represent the problem status of each segment. The status conditions are defined below.

The analysis results can then be viewed from the Tablespace Analysis Report tab.


Note:

Some space usage checks performed by the Tablespace Analysis tool require existing ANALYZE statistics. Up-to-date ANALYZE statistics will improve the quality of the Tablespace Analysis report. To perform an ANALYZE, use Oracle Enterprise Manager's Analyze Wizard. 


Viewing Tablespace Analysis Results

The analysis results can be viewed from the Tablespace Analysis Report tab.

Space management problems associated with the Tablespace Analysis warning and alert status flags are as follows.

An Alert status (Red Flag) may include one or more of the following problems:

A Warning status (Yellow Flag) may include one or more of the following problems:

Launching Reorg Wizard to Correct Space Problems

You may decide that you want to correct the space usage problems within the tablespace. To correct these problems, select Reorg Wizard from the Tools menu or the Reorg Wizard toolbar button. The Reorg Wizard allows you to reorganize the space used by problematic schema objects or the entire tablespace. You can also use the Reorg Wizard to repair migrated rows.

There are two options for launching the Reorg Wizard from Tablespace Map:

For more information on using the Reorg Wizard, see Chapter 23, "Introduction to the Reorg Wizard".


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