> http://www.mysql.com/doc/n/o/node_357.html > > explains the different string data types and the storage requirements: > > Column Type Storage required > [...] > VARCHAR(M) L+1 bytes, where L <= M and 1 <= M <= 255 > [...] > TINYBLOB, TINYTEXT L+1 bytes, where L < 2^8 > [...] > > These two storage requirements are exactly the same, so isn't a TINYBLOB > almost exactly like a VARCHAR(255) BINARY, and a TINYTEXT almost exactly > like a VARCHAR(255)? > > There are some differences listed at: > http://www.mysql.com/doc/B/L/BLOB.html > Apparently, in MySQL 3.23.2, the only difference between a TINYTEXT and a > VARCHAR(255) is that TEXT/BLOB fields can't have default values and > trailing spaces are not removed as they are in VARCHAR values. But are > those really the only differences?
No. There's another small, but important difference: TEXT/BLOB fields aren't stored directly in the row. Instead, a "pointer" is stored to the data, which is located "somewhere else". This is important where you have a lot of data stored in each row, as each row is limited to about 64k. TEXT/BLOB fields only count towards this limit with 1-4 bytes; a VARCHAR uses the L+1 bytes as you write. I assume that there is a small speed penalty in using TEXT/BLOB fields, as compared to VARCHARs. / Carsten -- Carsten H. Pedersen keeper and maintainer of the bitbybit.dk MySQL FAQ http://www.bitbybit.dk/mysqlfaq --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
