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
- Right-click a table and select Index Properties from the shortcut menu.
The Table Index Editor opens.
- 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.
- 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.
- 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.
- 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.
- 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.
- (Optional) Click the Commenttab and enter any comments that you want to associate with the object.
- (Optional) Click the Where Used tab to view where the object is used within the model.
- (Optional) Click the UDPtab to work with user-defined properties for the object.
- (Optional) Click the Notestab to view and edit user notes.
- (Optional) Click the Extended Notes tab to view or edit user notes.
- Click Close.
The DB2 for z/OS Table Index Editor closes.
|
Copyright © 2018 erwin, Inc.
All rights reserved.
|
|