Read-Only on Write Failure Feature | Teradata Unity - 17.00 - Read-Only on Write Failure Feature - Continuous Availability - Teradata Unity

Teradata® Unity™ User Guide

Product
Continuous Availability
Teradata Unity
Release Number
17.00
Published
September 2020
Language
English (United States)
Last Update
2020-09-15
dita:mapPath
fmz1594836948704.ditamap
dita:ditavalPath
qqk1595871525984.ditaval

From an Active state, a table may be placed in Read-only if a session encounters an error and the "Read-only on write failure" feature is turned on.

With the Read-Only on Write Failure parameter enabled, when a "INSERT to targetTable SELECT FROM sourceTable" fails on one system, the targetTable is Interrupted, a sourceTable becomes Read-Only. As a result, no further writes to sourceTable are allowed on system 1 until the INSERT-SELECT successfully completes recovery. If a write occurs on sourceTable, sourceTable is interrupted on system 1 (will need a recovery).

The feature is used in ETL environments where data is loaded to a stage table, then moved to a base table, and finally moved to a target table. This feature is not needed for a reporting environment. For mixed environment, it is recommended to keep the feature turned on.