In netezza, each table has the following internal columns which are invisible when querying rows from the table:

Code:
Type                    Column-Name  Storage
-----------------------------------------------------
rowid                     rowid               8 bytes
transaction id        createxid,        8 bytes
                              deletexid                     
dataslice               datasliceid       4 bytes
  • Rowid: Is the physical address of the row.
  • Createxid: Specifies the transaction that created the row.
  • Deletexid: Specifies the transaction that deleted the row. 0 indicates row is not deleted.
  • Datasliceid: Indicates the SPU number.