| DataGate® 16.0 for SQL Server Reference Guide
|
Index Considerations
The following table details important index (keys) considerations when converting or communicating between DataGate® for IBM i, DataGate® for SQL Server, and the core DataGate® program.
Considerations
|
Item |
DG/400 |
DSS |
DataGate |
|
Indexed logical files per physical file |
|
249 |
*NoMax |
|
Imposing 'uniqueness' via select/omit rules in logical files |
Supported |
Not directly supported. See work-around note below. |
Supported |
|
Logical field used as a key field must be based on a physical field with the same name |
No |
Yes. Notice that this eliminates the possibility of using Renamed, Concatenated and Sub-stringed fields as keys. |
No |
|
Maximum number of key fields per key |
|
16 |
250 |
|
Maximum length of key in bytes |
2,000 |
900 |
250 |
Work-around:
As a work-around to support "Imposing 'uniqueness' via select/omit rules in logical files":
- Change the logical file definition to allow duplicate keys.
- Create the logical file.
- Alter the SQL view with the "SCHEMABINDING" attribute.
- Add a Unique, Clustered Index to the SQL view (logical file).
- Make sure the "ARITHABORT" SET option is on/true for the database.