Physical Modeling › DB2 z/OS Property Editors › Define a DB2 z/OS Index

Define a DB2 z/OS Index

A primary key (PK) and a foreign key (IF) index is automatically created for each table in your model, based on the primary key and foreign key columns. If you designate columns as an alternate key group (AK) or inversion entry group (IE), the equivalent unique (AK) and non-unique (IE) indexes are also generated.

Use the Index editor to create alternate key (unique) and inversion entry (non-unique) indexes for tables in your model. After you create an index, you can use the Index editor to modify its properties, such as the index name, column members, physical properties, user-defined properties, and comments.

To define a DB2 z/OS Index

1. Right-click a table and select Index Properties from the shortcut menu.

   The Table Index Editor opens.

2. Select an index and work with the following options:

   Note: Click New on the toolbar to create an index. Use the Enter filter text text box to filter a very large list of indexes to locate the one you want to work with.

   Show FK Indexes

   Displays foreign key indexes in the Index list.

   Physical Name

   Specifies the name of the index.

   Schema

   Specifies the default schema for the index.

   Type

   Shows the key group type. This is a read-only field.

   Is Unique

   Specifies that the fields defined in the index must be unique.

   Where Not Null

   Specifies that a table cannot have two or more rows with the same value of the index key; this applies when you select the Is Unique check box.

   Physical Only

   Lets you select whether the index should be suppressed from a logical model and appear in a physical model only.

   Generate

   Specifies whether or not to generate DDL for this object during Forward Engineering.

   Generate As Consraint

   Specifies whether or not to enforce the Is Unique option as a constraint while generating the index.

3. Click the Members tab and work with the following options:

   Column

   Specifies the columns that you want to include in the index.

   Index Member Sort Order

   Specifies the order in which you want to sort the index columns. Select from the drop-down list; valid values are Ascending, Descending, and Random.

   Column Expression

   Specifies a key-expression that returns a scalar value. You cannot include the same expression more than once in an index. This field is enabled only when you create a non-unique index. For more information about including key expressions in indexes, see the IBM DB2 for z/OS documentation.

   Column Editor

   Displays the Column Editor for DB2 for z/OS so that you can edit the selected column.

   Reset Order

   Displays the Reset Order dialog where you can select the reset option you want to use.

4. Work with the following fields on the General tab:

   Constraint Name

   Specifies the constraint associated with the index.

   Clustered

   Specifies whether the index is clustered or nonclustered.

   Is Partitioned

   Specified whether or not the index is data partitioned.

   DB2 z/OS Type

   Specifies the index type. Valid values are Type2, Data Partitioned, and Partitioning.

   Pad Variable Length Columns

   Specifies that varying-length string columns within the index are always padded with the default pad character to their maximum length. Clear the check box to indicate NOT PADDED.

   Define Data Sets

   Specifies that the data sets are created when the index is created. Clear the check box to set the DEFINE parameter to NO.

   Use Bufferpool

   Identifies the buffer pool to use for the index.

   Close

   Specifies that the index is eligible for closing. The CLOSE parameter specifies whether or not the data set is eligible to be closed when the index is not being used and the limit on the number of open data sets is reached. Select from the drop-down list.

   Defer

   Specifies whether or not to build the index during the execution of the CREATE INDEX statement. Default is No, which means the index is built.

   Piece Size

   Specifies the maximum addressability of each data set for a secondary index. Enter a valid integer (see your DB2 z/OS documentation for specific information on valid integers).

   Copy

   Indicates that the COPY utility is allowed for the index.

   Is Compressed

   Specifies that the index will use index compression. Clear the check box to set the parameter to COMPRESS NO.

5. Click the Using Clause tab and work with the following options:

   Volume Catalog

   Specifies that the first data set of the index is managed by the user. Catalog Name identifies the linear VSAM data sets that are cataloged in an integrated catalog facility catalog.

   Storage Group

   Specifies that DB2 manages the data set.

   Primary Space Allocation

   Specifies the minimum primary space allocated to a DB2-managed data set. If you do not specify any value, DB2 uses a default value.

   Secondary Space Allocation

   Specifies the minimum secondary space allocated to a DB2-managed data set. If you do not specify any value, DB2 uses a formula to calculate the value. For more information, refer to IBM DB2 for z/OS documentation.

   Erase When Deleted

   Specifies whether or not to delete the DB2-managed data sets when the index is dropped while executing a utility or an SQL statement.

   Free Page Interval

   Specifies the frequency at which you want to leave a page of free space when you create index entries while executing a DB2 utility or when you create an index for a table with existing rows.

   Percent Free

   Specifies the percentage of free space you want to leave in each nonleaf page and leaf page when you add entries to an index or index partition while executing a DB2 utility or when you create an index for a table with existing rows.

   Group Bufferpool

   Specifies the index pages that are written to the group buffer pool and applies to the data sharing environment. Select from the drop-down list; valid values are: Changed, All, and None.

6. Click the Partition tab and work with the following options:

   Name

   Specifies a name for the partition.

   Partition Number

   Specifies the highest value of the sorting sequences of index columns in a single partition of a partitioning index.

7. (Optional) Click the Comment tab and enter any comments you want associated with the index.
8. (Optional) Click the Where Used tab to view where the index is used in the model.
9. (Optional) Click the UDP tab to work with user-defined properties for the index.
10. (Optional) Click the Notes tab to view history information and view or edit user notes.
11. Click Close.

    The DB2 for z/OS Table Index Editor closes.

More information:

Specify DB2 z/OS Using Clause Parameters

Define DB2 z/OS Table Partition Elements

Define DB2 z/OS Table or Index Partitions

Add a Comment in a Property Editor

Add a UDP in a Physical Property Editor