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