Tables with VARCHAR(<31) are created as row_format = Fixed

[Philip Stoev]

If a table contains only columns with VARCHAR(30) or less, the table is created as Fixed regardless of the ROW_FORMAT or KEY_BLOCK_SIZE settings. This does not correspond to any documented limitation:

To repeat:

CREATE TABLE t1 ( f1 VARCHAR(30)) ENGINE=HEAP ROW_FORMAT=DYNAMIC;

SHOW TABLE STATUS:

           Name: t1
         Engine: MEMORY
        Version: 10
     Row_format: Fixed
           Rows: 0
 Avg_row_length: 18
    Data_length: 0
Max_data_length: 943704
   Index_length: 0
      Data_free: 0
 Auto_increment: NULL
    Create_time: NULL
    Update_time: NULL
     Check_time: NULL
      Collation: latin1_swedish_ci
       Checksum: NULL
 Create_options: row_format=DYNAMIC
        Comment: