(mysql.info) static-format

 
 14.1.3.1 Static (Fixed-Length) Table Characteristics
 ....................................................
 
 Static format is the default for `MyISAM' tables. It is used when the
 table contains no variable-length columns (`VARCHAR', `VARBINARY',
 `BLOB', or `TEXT'). Each row is stored using a fixed number of bytes.
 
 Of the three `MyISAM' storage formats, static format is the simplest
 and most secure (least subject to corruption). It is also the fastest
 of the on-disk formats due to the ease with which rows in the data file
 can be found on disk: To look up a row based on a row number in the
 index, multiply the row number by the row length to calculate the row
 position. Also, when scanning a table, it is very easy to read a
 constant number of rows with each disk read operation.
 
 The security is evidenced if your computer crashes while the MySQL
 server is writing to a fixed-format `MyISAM' file. In this case,
 `myisamchk' can easily determine where each row starts and ends, so it
 can usually reclaim all rows except the partially written one. Note
 that `MyISAM' table indexes can always be reconstructed based on the
 data rows.
 
 Static-format tables have these characteristics:
 
    * `CHAR' columns are space-padded to the column width. This is also
      true for `NUMERIC', and `DECIMAL' columns created before MySQL
      5.0.3.  `BINARY' columns are space-padded to the column width
      before MySQL 5.0.15. As of 5.0.15, `BINARY' columns are padded with
      `0x00' bytes.
 
    * Very quick.
 
    * Easy to cache.
 
    * Easy to reconstruct after a crash, because rows are located in
      fixed positions.
 
    * Reorganization is unnecessary unless you delete a huge number of
      rows and want to return free disk space to the operating system.
      To do this, use `OPTIMIZE TABLE' or `myisamchk -r'.
 
    * Usually require more disk space than dynamic-format tables.
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