MySQL Determine longest VarChar length

Question

I am trying to optimize my database. In order to do so, I need to be able to determine the longest data entry in a varchar column, and then trim the column definition to just a

Answer 1

You can do this by using the following statement

SELECT column_name FROM database.table PROCEDURE ANALYSE(1,1);

The Max_length value of the results from this will give you the longest varchar in that column.

So in this case assuming you want to investigate the output column then you can run the following

SELECT output FROM poller_output PROCEDURE ANALYSE(1,1);

The advantage of this is that it will also give you the optimal fieldtype in the return values which will be something along the lines of

VARCHAR(56) NOT NULL