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(mysql.info)Static format

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Static (Fixed-length) Table Characteristics
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This is the default format. It's used when the table contains no
`VARCHAR', `BLOB', or `TEXT' columns.

This format is the simplest and most secure format. It is also the
fastest of the on-disk formats. The speed comes from the easy way data
can be found on disk. When looking up something with an index and static
format it is very simple. Just multiply the row number by the row
length.

Also, when scanning a table it is very easy to read a constant number of
records with each disk read.

The security is evidenced if your computer crashes when writing to a
fixed-size MyISAM file, in which case `myisamchk' can easily figure out
where each row starts and ends. So it can usually reclaim all records
except the partially written one. Note that in MySQL all indexes can
always be reconstructed:

   * All `CHAR', `NUMERIC', and `DECIMAL' columns are space-padded to
     the column width.

   * Very quick.

   * Easy to cache.

   * Easy to reconstruct after a crash, because records are located in
     fixed positions.

   * Doesn't have to be reorganized (with `myisamchk') unless a huge
     number of records are deleted and you want to return free disk
     space to the operating system.

   * Usually requires more disk space than dynamic tables.