15.10 - Method 1: Alter Existing Transaction-Time Table - Teradata Database

Teradata Database ANSI Temporal Table Support

prodname
Teradata Database
vrm_release
15.00
15.10
category
Programming Reference
featnum
B035-1186-015K

This method:

  • requires that the executor have the NONTEMPORAL privilege in the database, and that the database be enabled to recognize that privilege. For more information on the NONTEMPORAL privilege, see Temporal Table Support.
  • cannot be used if the transaction-time table is row partitioned on the beginning or ending bound of the transaction-time.
  • is not recommended for large, column-partitioned tables because for these tables the update operation in Step 4 can be very resource intensive and time consuming.
  • 1 Note all the constraints on the transaction-time table.

    2 Drop all the constraints from the transaction-time table.

    3 Use NONTEMPORAL ALTER TABLE to add two new columns of type TIMESTAMP(6) WITH TIME ZONE. For the purposes of this procedure, assume the columns are named sys_start and sys_end. These will hold the beginning and ending bound values of the new SYSTEM_TIME derived period column.

    4 Use NONTEMPORAL UPDATE to populate the new columns with the start and end values of the existing transaction-time columns or derived period column.

    5 Use NONTEMPORAL ALTER TABLE to drop the existing transaction-time column. Use the WITHOUT DELETE option to preserve the historical closed rows, which would otherwise be deleted automatically when you drop the transaction-time column:

    ALTER TABLE transaction_time_table_name 
      DROP transaction_time_column WITHOUT DELETE

    6 Use ALTER TABLE to create the SYSTEM_TIME derived period column and to add attributes to the set the sys_start and sys_end columns in the same ALTER TABLE statement:

    ALTER TABLE transaction_time_table_name
     ADD PERIOD FOR SYSTEM_TIME(sys_start,sys_end)
     ADD sys_start TIMESTAMP(6) WITH TIME ZONE NOT NULL
       GENERATED ALWAYS AS ROW START
     add sys_end TIMESTAMP(6) WITH TIME ZONE NOT NULL
       GENERATED ALWAYS AS ROW END;

    7 Add system versioning to make the new table an ANSI system-time temporal table:

    ALTER TABLE transaction_time_table_name 
     ADD SYSTEM VERSIONING;

    8 Recreate all the constraints that were dropped in step 2. Note that ANSI constraints behave as NONSEQUENCED constraints.