17.10 - Restrictions - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - Data Types and Literals

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1143-171K
Language
English (United States)
  • You cannot use ALC to compress columns that have a data type of structured UDT.
  • The TD_LZ_COMPRESS and TD_LZ_DECOMPRESS system functions compress all large UDTs including UDT-based system types such as Geospatial, XML, and JSON. However, if you write your own compression functions, the following restrictions apply:
    • Custom compression functions cannot be used to compress UDT-based system types (except for ARRAY and Period types).
    • Custom compression functions cannot be used to compress distinct UDTs that are based on UDT-based system types (except for ARRAY and Period types).
  • You cannot write your own compression functions to perform algorithmic compression on JSON type columns. However, Teradata provides the JSON_COMPRESS and JSON_DECOMPRESS functions that you can use to perform ALC on JSON type columns.
  • You cannot use ALC to compress temporal columns:
    • A column defined as SYSTEM_TIME, VALIDTIME, or TRANSACTIONTIME.
    • The DateTime columns that define the beginning and ending bounds of a temporal derived period column (SYSTEM_TIME, VALIDTIME, or TRANSACTIONTIME).

    You can use ALC to compress period data types in columns that are nontemporal; however, you cannot use ALC to compress derived period columns.

    For details about temporal tables, see Teradata Vantage™ - Temporal Table Support, B035-1182 and Teradata Vantage™ - ANSI Temporal Table Support, B035-1186.

  • You cannot specify multi-value or algorithmic compression for a row-level security constraint column.