Re: Char & Varchar2

In article <34fb2f35.107655129_at_192.86.155.100>, Thomas Kyte <tkyte_at_us.oracle.com> writes
>
>Simply put, a CHAR is a VARCHAR2 that is blank padded to its maximum length.
>The are stored the same on disk.
>
>A char and varchar2 are stored on disk in the same fashion -- both have a
>leading byte(s) to indicate their length. A CHAR(5) will always (when not
>null)
>take 5 bytes for the data plus 1 byte for the length. a Varchar2(5) with the
>value "ABC" will take 3 bytes for the data and 1 byte for the length.
>
>A CHAR therefore, always consumes maximum storage. This is good and bad. Its
>bad in that it eats alot of space on disk. Good in that a varchar2, if updated
>frequently with values of different lengths, can cause a row to migrate or
>chain. A CHAR, since it takes maximum storage, will not cause a row to migrate
>(unless it goes from being NULL to NOT NULL that is).
>
Thomas,
Your point taken entirely. However, unless there are exceptional circumstances (such as one could posit based on your example) I would say that in the real world, a good rule of thumb would be simply never to use CHAR, and always to use VARCHAR2. Unless of course, I am missing something, which is entirely possible.

-- 
Paul Brewer