2.14.1.4 VARLEN Encoding and Performance

• The presence of VARLEN encoded VARCHAR or CHAR columns does not affect table load performance.

• Table load and change propagation operations perform more slowly on VARLEN encoded TEXT type columns than on VARLEN encoded VARCHAR columns.

• There are two main differences with respect to HeatWave result processing for variable-length encoding compared to dictionary encoding:

  • A dictionary decode operation is not required, which means that fewer CPU cycles are required.

  • Because VARLEN encoded columns use a larger number of bytes than dictionary-encoded columns, the network cost for sending results from HeatWave to the MySQL DB System is greater.