Specifying storage allocation properties

These steps are part of the larger task of Creating an index. When you complete the steps for specifying the storage allocation properties, return to Creating an Index.

To specify storage allocation properties:

1. In the Index Space Management page, select Managed by user or Managed by DB2 from the Data Set Management radio buttons.
   
   
2. If you selected Managed by user, type or select the Catalog name. The name specifies the integrated catalog facility where the data sets for this indexed are catalogued. If the catalog name is greater than eight characters, then you must use an alias for this setting.
   
   
3. If you selected Managed by DB2:
   
   1. Type or select a storage group name. The storage group must be defined at the current server and it must include at least one volume serial number in its description.
      Important: The privilege set must contain SYSADM authority, SYSCTL authority, or USE privileges on the specified storage group.
      
      
   2. Type the Minimum primary space allocation.This value should be an integer between 12 and 4194304, inclusive. Smaller or larger values will use 12 or 4194304, respectively.
      
      
   3. Type the Minimum Secondary space allocation. If you want DB2 enabled to extend the data set for the index if necessary, this value should be an integer between 12 and 131068, inclusive. If you specify 0, DB2 cannot extend the data set. If you specify a Minimum primary space and do not specify this value, then DB2 calculates a default secondary space allocation. The default is the larger of two values: (1) 10 percent of the minimum primary space allocation or (2) 3 times the index page size, which is 3 * 4 KB.
      
      
   4. Select the Erase data sets when the index is dropped check box to erase data sets for the index or partition when they are deleted during the execution of a utility or when you drop the index. The index or partition must be in the stopped state when you are altering the index.
      
      
4. If you want to explicitly manage free space in the index space, select the Specify management scheme for free space check box.
   
   
   1. In the Free space reserved field, select an integer value from 0 to 255 that describes how often to leave a page of free space when index entries are created as the result of executing a DB2 utility. One free page is left for every integer pages.
      
      
   2. In the Percentage of free space in a page field, select an integer value from 0 to 99 to determine the percentage of free space to leave in each nonleaf page and subpage when entries are added to the index or partition as the result of executing a DB2 utility. The first entry is loaded without restriction. When additional entries are placed in a nonleaf or subpage, the percentage of free space is at least as great as integer.
      
      
5. From the Cache pages in a group buffer pool radio buttons, select:
   
   

   Only on Update (CHANGED)

   When more than one DB2 member has the index or partition open and at least one member has the index open for an UPDATE operation, updated pages are written to the group buffer pool.

   Always cache pages (ALL)

   Pages are cached in the group buffer when read in from DASD.

   Important: These values are ignored and no pages are cached if the group buffer pool is defined for cross-invalidation use only.
   

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