17.10 - Considerations For Dropping Hash Indexes to Enable Client Batch Load Utilities - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL Data Definition Language Detailed Topics

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1184-171K
Language
English (United States)

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