Changing Table Structures - Mastering phpMyAdmin 2.8 for Effective MySQL Management - page 86

There are three parameters that control the layout of the text area that will be
displayed in Insert or Edit mode for the TEXT fields. First, the number of columns
and rows for each field is defined by:
$cfg['TextareaCols'] = 40;
$cfg['TextareaRows'] = 7;
This gives (by default) the following space to work on a TEXT field:
The settings impose only a visual limit on the text area, and a vertical scroll bar is
created by the browser if necessary.
Although MEDIUMTEXT , TEXT , and LONGTEXT
columns can accommodate more than 32K of data, some
browsers cannot always edit them with the mechanism
offered by HTML: a text area. In fact, experimentation has
convinced the phpMyAdmin development team to have
the product display a warning message, if the contents are
larger than 32K, telling users that it might not be editable.
The last parameter has an impact for LONGTEXT fields. Setting $cfg['LongtextDo
ubleTextarea'] to TRUE doubles the available editing space.
BLOB (Binary Large Object) Fields
BLOB fields are usually used to hold binary data (such as images and sounds), even
though the MySQL documentation implies that TEXT fields could be used for this
purpose. The MySQL 5.1 manual says "In some cases, it may be desirable to store
binary data such as media files in BLOB or TEXT columns" but another phrase,
" BLOB columns are treated as binary strings (byte strings)" seems to indicate that
binary data should really be stored in BLOB fields. Thus, phpMyAdmin's intention
is to work with BLOB fields to hold all binary data.