Space Analyst for Microsoft - Map Tab

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The Map tab displays a graphical file map that displays extent placement for objects within database files.

The Map tab lets you view a graphical layout regarding the physical placement of every object inside a selected database and file. The map helps identify allocated and unused extents throughout a database file. An object grid is also present that lets you view detailed information about every object's storage usage in that file. Keep in mind that an object can span more than one file.

The Space Info section at the top contains information regarding the total number of extents allocated to a database file, a count of extents that contain table data, a count of extents that contain index data, and a count of extents that contain text data.

Databases are comprised of logical pages, each of which is a fixed 8KB in size. Note that the 8KB page is also a unit of I/O, which affects performance and locking. Extents are collections of database pages. An extent is made up of eight, 8K pages and is therefore 64KB in size. Extents are the graphical "blocks" displayed in the map.

Extents come in two flavors - uniform and mixed. Uniform extents ascribe all eight database pages to a single object, whereas mixed extents have the potential to hold multiple objects. With mixed extents, SQL Server tries to preserve space by not letting very small objects take up an entire extent and therefore waste a lot of space. By placing your mouse pointer over an extent "block" in the map, Space Analyst will present a pop-up dialog displaying what object(s) is/are contained in that extent.

The table below describes the options and functionality on the Map tab of Space Analyst:

Option Description

Space Info

Displays total extent count, extents with tables count, extents with indexes count, and extents with text count. Note that an extent can contain more than one object and more than one object type.


Displays object extent data from beginning to end of the database or file. All blocks in the map are the same size. A Microsoft SQL Server extent is 64KB in size or 8, 8K pages. Purple - Indicate extents that have been allocated to objects (used), and extents that are free. Green - Free extents.


Displays table owner.

Table name

Displays table name.

Object type

Displays object type.

Index name

Displays index name.

Pages used

Displays pages used.

Pages allocated

Displays pages allocated.

In extents

How many extents each object is in.

Table id

Displays table id.

Index id

Displays index id.

The Tablespace Map tab includes the following buttons:

Button Description


Opens the Tablespace Map Legend.


Opens the Display window. The Display window lets you specifies the magnification level for the Tablespace Map.

Fit to Window

Fits the Tablespace Map to the window.

Full Screen

Fits the Tablespace Map to the full screen.

Print Map

Opens the Print dialog to print the Tablespace Map.

Available Functionality

The following functionality is available in the Command menu, shortcut menu, and toolbar: