16.20 - Considerations For Dropping Secondary Indexes to Enable Client Batch Load Utilities - Teradata Database - Teradata Vantage NewSQL Engine

Teradata Vantage™ SQL Data Definition Language Detailed Topics

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Release Date
March 2019
Content Type
Programming Reference
Publication ID
B035-1184-162K
Language
English (United States)

You cannot drop a secondary index to enable batch data loading by utilities such as MultiLoad and FastLoad as long as queries are running that access that secondary index. Each such query places a READ lock on the hash index while it is running, so it blocks the completion of any DROP INDEX transaction until the READ lock is removed. Furthermore, as long as a DROP INDEX transaction is running, batch data loading jobs against the underlying table of the index cannot begin processing because of the EXCLUSIVE lock DROP INDEX places on the base table that defines the index.