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ISAM Tables
===========

You can also use the deprecated ISAM table type. This will disappear
rather soon because `MyISAM' is a better implementation of the same
thing. ISAM uses a `B-tree' index. The index is stored in a file with
the `.ISM' extension, and the data is stored in a file with the `.ISD'
extension.  You can check/repair ISAM tables with the `isamchk'
utility. Note: Crash recovery.

`ISAM' has the following features/properties:

   * Compressed and fixed-length keys

   * Fixed and dynamic record length

   * 16 keys with 16 key parts/key

   * Max key length 256 (default)

   * Data is stored in machine format; this is fast, but is machine/OS
     dependent.

Most of the things true for `MyISAM' tables are also true for `ISAM'
tables. Note: MyISAM. The major differences compared to `MyISAM'
tables are:

   * ISAM tables are not binary portable across OS/Platforms.

   * Can't handle tables > 4G.

   * Only support prefix compression on strings.

   * Smaller key limits.

   * Dynamic tables get more fragmented.

   * Tables are compressed with `pack_isam' rather than with
     `myisampack'.

If you want to convert an `ISAM' table to a `MyISAM' table so that you
can use utilities such as `mysqlcheck', use an `ALTER TABLE' statement:

     mysql> ALTER TABLE tbl_name TYPE = MYISAM;