Indexes Tab
How to Access
, select the Indexes tab. If no table is selected in the Filelist dialog, nothing will happen when you select this menu item. The dialog will only show if at least one table is selected.
Side Button in the Filelist dialog, Convert Database, select the Indexes tab.
If you wish to make the indexes on the migrated table different than the DataFlex table, use this tab to make those changes. Please use caution when making changes in this tab, see the note below.
Note
Indexes on the target server are created based on the indexes in the DataFlex data file. These are also the default indexes on the server. Mertech recommends that you keep the indexes the same and make no changes during the first phase of data migration. Working with defaults and allowing Flex2SQL to handle data migration and index creation ensure proper and optimal functioning of the driver. Once you develop a familiarity with SQL databases and the Mertech drivers, you can make modifications in index structures to enhance performance.
Primary Key
The Primary Key tab shows the index number in the DataFlex file and the fields that comprise the index and are used to create a primary key on the target server. By default, Index 1 is selected in a DataFlex file to be the primary key in the table, but the user can change this. For fast and efficient access, it is suggested that the primary key be comprised of columns that give maximum selectivity.
Flex2SQL selects the Inverse Key checkbox in the Primary Key tab and Native Index tab if one segment is DESC or C/S.
Primary Index
RECNUM is the primary index in a DataFlex file. Whenever you perform any operation using RECNUM, the RECNUM index (Index.0) is used. If you are using only the DataFlex database, there is no choice; RECNUM is the primary index. However, with other databases, you can specify any index as the primary index. In ORAFlex, RECNUM, by default, behaves just like the RECNUM field in DataFlex. However, the user can select another index to be the primary index. This is controlled during migration or can be changed after migration in the intermediate file by changing the PRIMARY_INDEX token to an index number specified in the intermediate file.
For ORAFlex, you can select an index created on a non-numeric field to be the primary index. But to make this work, you have to change the definition of the RECNUM field in your .FD file from a numeric to a string data type. For example, if you have a definition like:
#REPLACE VENDOR.RECNUM |FN21,0
In your .FD file, you will have to change this to:
#REPLACE VENDOR.RECNUM |FS21,0
Native Index
The Native Index tab allows you to control which indexes are created on the server. If you do not plan to change your DataFlex program, Mertech recommends that you use the default selections that are presented to you by Flex2SQL. The primary key is not selected because the primary key is always created.
Bottom Controls
The controls at the bottom of the dialog remain the same regardless of the tab selected.
