Special columns
Deployment options: IBM Netezza Appliance
IBM Netezza Appliance
The backup and restore method that you use affects how the system retains specials. The term
specials refers to the end-user-invisible columns in every table that the system
maintains. The specials include rowid, datasliceid,
createxid, and deletexid.
The
following table describes how the backup method affects these values.
| Special | The nzbackup and nzrestore commands | Compressed external tables | Text format external tables |
|---|---|---|---|
rowid |
Retain. | Retain. | Not unloaded. |
datasliceid |
Retain when the system model size stays the same, otherwise recalculates. | Retain when the model size stays the same, otherwise recalculates. | Recalculate. |
createxid |
Receive the transaction ID of transaction that does the restore. | Receive the transaction ID of transaction that does the restore. | Receive the transaction ID of transaction that does the restore. |
deletexid |
Set to zero. | Set to zero. | Set to zero. |