16.20 - Usage Notes - Teradata Database - Teradata Vantage NewSQL Engine

Teradata Vantage™ SQL Data Definition Language Syntax and Examples

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Published
March 2019
Language
English (United States)
Last Update
2019-05-24
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Altering the Hash Index to a Sparse Map Without Specifying the Colocation Option

If you alter the hash index to use a sparse map without specifying the COLOCATE USING clause and the hash index previously used a sparse map, the colocation name does not change. Otherwise, the colocation name defaults to database_index, where database is the name of the database or user followed by an underscore (_) and index is the name of the hash index. If database exceeds 63 characters, database is truncated to 63 characters. If index exceeds 64 characters, index is truncated to 64 characters.

Locks During the Alter Hash Index Operation

A read lock is placed on the hash index during the copy to the new map. The lock is upgraded to an exclusive lock while DBC.TVM is updated and the transaction is committed.

Indexes and the Alter Table Map Operation

Secondary indexes for the table are moved or rebuilt using the new map.

Hash indexes on the base table are not moved when the table is moved to a new map. You must use ALTER HASH INDEX.

Secure Zones and Sparse Maps

For a sparse map, you must be in the same secure zone as the sparse map.