Referential Integrity Revalidation on LOB Tables - Teradata Database

Teradata Database Node Software Migration Guide

Product
Teradata Database
Release Number
15.10
Published
November 2017
Language
English (United States)
Last Update
2018-04-25
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dita:id
B035-5942
lifecycle
previous
Product Category
Software

Referential integrity is the term used to define the keys and checks that ensure that related values and indexes can be maintained between tables within the database. These relationships are also known as foreign key references. Referential integrity is a connection between multiple tables such that changes to one table cause changes in the other table.

After a migration where data rows may have been redistributed to different AMPs, the Referential Indexes (RIs) must be revalidated before the tables with referential integrity can be accessed. Establishment of a foreign key reference creates a Referential Integrity error table. Because of the way table names are constructed, any data rows in the RI error table contain information that is valid only on that system. If the RI error table is migrated to a different system, any attempt to revalidate referential integrity on the new system fails. If an RI error table is migrated to a different system, the table should be emptied.

Referential integrity on LOB tables should be dropped prior to archival. Otherwise, the rehashlobs.pl script fails because it cannot drop the rows on the original table involved in a reference.