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HeatWave User Guide  /  ...  /  Variable-length Encoding

11.4.1 Variable-length Encoding

Variable-length (VARLEN) encoding has the following characteristics:

  • It is the default encoding type. No action is required to use variable-length encoding. It is applied to string columns by default when tables are loaded with the exception of string columns defined explicitly as dictionary-encoded columns.

  • It minimizes the amount of data stored for string columns by efficiently storing variable length column values.

  • It is more efficient than dictionary encoding with respect to storage and processing of string columns with a high number of distinct values relative to the cardinality of the table.

  • It permits more operations involving string columns to be offloaded than dictionary encoding.

  • It supports all character sets and collation types supported by the MySQL DB System. User defined character sets are not supported.

  • VARLEN columns can be declared as NULL.