17.05 - Nonsequenced Updates - Teradata Database

Teradata Vantage™ - Temporal Table Support

Advanced SQL Engine
Teradata Database
June 2020
Programming Reference

A nonsequenced update modifies the specified rows across all states or any state. A nonsequenced update ignores valid-time semantics when updating a row of a table with valid time.

A nonsequenced update operates on only open rows for a table with transaction time. A nonsequenced update treats a valid-time column like a regular column for a table with valid time. For a valid-time table, a nonsequenced update does not create multiple rows like in a current or sequenced update.

For a table with transaction time, a nonsequenced update of a row first closes out the existing qualified row and inserts a new row with the updated columns only when the column values change. If there are no changes made to the row, the existing row is not closed. For a valid-time table, a nonsequenced update modifies the existing qualified row like a regular update.

Because a nonsequenced update permits updates to the valid-time column like a conventional Period column, the valid-time column can be used in the assignment list.

All modifications on a transaction-time table or a bitemporal table cause changes to be recorded, regardless of whether the modifications are in the same transaction.

A nonsequenced update that joins two or more tables is like a regular join. The valid-time column may participate in the join like a regular column.