Variable-length encoding (
VARLEN) has the
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 that are 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 collations types supported by the MySQL DB System. User defined character sets are not supported.
VARLENcolumns can be declared as NULL.