Re: What does it mean?

[Russell Dyer]

The maximum length for a VARCHAR column can be specified as 1 to 255 before MySQL 4.0.2, 0 to 255 as of MySQL 4.0.2, and 0 to 65,535 as of MySQL 5.0.3. (The maximum actual length of a VARCHAR in MySQL 5.0 is determined by the maximum row size and the character set you use. The maximum effective length is 65,532 bytes.) Basically, it seems that your version of MySQL is converting VARCHAR(1000) to a TEXT column type--hence the comment about BLOB/TEXT in the error message.

Only the first several bytes of a column is used when sorting. The number of bytes used is based on the value of the max_sort_length variable for your server. The default value of max_sort_length is 1024. This value can be changed using the --max_sort_length option when starting the mysqld server or with the SET statement.

Relating this background to your question and situation, when you say UNIQUE on a TEXT file, you're suggesting MySQL index on possibly more than the max_sort_length variable amount. It can't and won't do that, thank you very much. At least this is my assessment. I could be totally wrong.