Use the Estimate Size window to estimate the amount of
storage space required for a new or existing table or index. The estimated
storage space is determined from the definition of a particular table
and its dependent indexes. Minimum and maximum storage values are
estimated for these objects.
About this task
Reasons to estimate space requirements for tables and
indexes include:
- To create a new table and determine the size of the table space
required.
- To create a new table based on the size estimate of an existing
table.
- To rearrange a table space. For example, you want to move a table
from table space A to table space B, and you want to know how much
space the table uses in table space A.
- To identify the amount of space occupied by different objects
in the table space because the system is running out of storage space.
Note: For DB2® Enterprise Server Edition databases,
size estimates are based on the logical size of the data in the table
instead of by database partition.
To open the Estimate Size
window, from the Control Center, expand the object tree until you
find the
Tables folder or
Indexes folder. Click the
Tables folder
or
Indexes folder. Any existing tables or indexes are displayed
in the pane on the right side of the window (contents pane).
- For an existing table or index, right-click the table or index
you want in the contents pane, and click Estimate Size in the
pop-up menu.
- When you are creating a table or index, right-click the table
or index folder and click Create Table or Create Index in
the pop-up menu. The Create Table wizard or Create Index window opens.
Complete the information required to create a table or index. Select Estimate
Size from the Create Table wizard or Create Index window.
Since every row added to the table affects the storage
used by the indexes as well as tables, the table and all its related
indexes are displayed in the Estimate Size window.
If recent
statistics are not available for the table or index, click Run
statistics before updating the New total number of rows and New
average row length fields and running a size estimate. The calculation
of the size estimate can then be based on more accurate information.
In the Run Statistics window that opens, either accept the default
or select a different value for New total number of rows.