About Overriding Locks for Access - Teradata Data Mover

Teradata Data Mover User Guide

Product
Teradata Data Mover
Release Number
16.10
Published
June 2017
Language
English (United States)
Last Update
2018-03-29
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kmo1482331935137.ditamap
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dita:id
B035-4101
lifecycle
previous
Product Category
Analytical Ecosystem
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 and JDBC utilities can be used with this feature. Teradata ARC cannot be used.