Override Transaction Locks for Access | Teradata Data Mover - 17.11 - About Overriding Locks for Access - Teradata Data Mover

Teradata® Data Mover User Guide

Product
Teradata Data Mover
Release Number
17.11
Release Date
October 2021
Content Type
User Guide
Publication ID
B035-4101-091K
Language
English (United States)
The Teradata Database system places a lock on a table during every table transaction. For example, if a transaction is taking place on the source table, you cannot run a read operation until the previous transaction is complete. However, the override lock for access feature allows you to override the default lock and read data from the source table, which could be in the middle of a transaction. This functionality (also known as a dirty read) contains the risk of copying data to a target table that has not been committed on the source table:
Be extremely careful when using this feature.

This feature is optional and can only be specified using XML, not the command-line interface. In the object list XML file, override the default lock by adding an override_lock_access element that is set to true. The functionality works on a per-table basis, therefore specify the override_lock_access element under the specific table where the override should occur.

The example below shows the correct location for the override_lock_access element.

<database selection="unselected">
	<name>srcDatabase</name>
	<table selection="included">
		<name>srcTable</name>
		<validate_row_count>all</validate_row_count>
		<override_lock_access>true</override_lock_access>
		<compare_ddl>true</compare_ddl>
	</table>
</database>

The default value for the override_lock_access element is false.

Only Teradata PT API, T2T, and JDBC utilities support this feature. Teradata DSA cannot be used.