myisamchk — MyISAM Table-Maintenance Utility The size of the data file pointer, in bytes. It is usually 2, 3, 4, or 5 bytes. Most tables manage with 2 bytes, but this cannot be controlled from MySQL yet. For fixed tables, this is a row address. For dynamic tables, this is a byte address. The size of the index file pointer, in bytes. It is usually 1, 2, or 3 bytes. Most tables manage with 2 bytes, but this is calculated automatically by MySQL. It is always a block address. How long the table data file can become, in bytes. How long the table index file can become, in bytes. How much space each row takes, in bytes. The  table description  part of the output includes a list of all keys in the table. For each key, myisamchk  displays some low-level information: This key’s number. This value is shown only for the first column of the key. If this value is missing, the line corresponds to the second or later column of a multiple-column key. For the table shown in the example, there are two  table description  lines for the second index. This indicates that it is a multiple-part index with two parts. Where in the row this portion of the index starts. How long this portion of the index is. For packed numbers, this should always be the full length of the column. For strings, it may be shorter than the full length of the indexed column, because you can index a prefix of a string column. The total length of a multiple-part key is the sum of the  Len  values for all key parts. Whether a key value can exist multiple times in the index. Possible values are  unique  or  multip. (multiple). What data type this portion of the index has. This is a  MyISAM  data type with the possible values packed ,  stripped , or  empty . Address of the root index block. • Datafile pointer • Keyfile pointer • Max datafile length • Max keyfile length • Recordlength • Key • Start • Len • Index • Type • Root • Blocksize 574