column type's size

[Anon]

As far as I know in MySQL, mediumint is 3 bytes and int is 4 bytes. How come some php program make it larger like phpbb made mediumint 8 bytes and int 10 bytes. What are the purposes or those are mistakes?

[[deleted]]

you can't change the daatypes in mysql, you can only choose different types.

WHat the purpose is is defined only by what you want to store in them.
If you want to store numbers from 0-255, then tinyint (1 byte) will do. If you need more, you'll have to use a larger datatype.

[Anon]

I mean in the question: what is the difference between int(4) and int(10)? is it a waste of space to have int(10)?

[[deleted]]

4=4bytes, 10=10 bytes.

If you can find any application that requires a 1 byte integer (2^80, that's a range from zero to 1208925819614629174706176) then you're a better man than me 🙂

the most you'll ever need in any normal app is int4, sometimes int8 if you have millions of rows and thousands of mutations on sequence-columns per day.

So int(10) would be a wast of space if you never use more than 4 bytes.
Wether it's a problem is a different matter because int(10) uses 6 bytes more than int(4), so you 'waste' a huge 6 bytes per row. If your rows are 300 bytes, then 6 bytes is not that big a deal.

[Anon]

An int in Mysql is always 4 bytes. The number within parenthesis is a display length.

[[deleted]]

No, in mysql and INT is as large as you define it to be. The display size is just to help you mess up.

You can define a smallint as int(10), and get into big trouble.

In regular databases when we say int(10) we mean a ten-byte integer.

[Anon]

http://www.mysql.com/doc/n/o/node_366.html

in this page it is stated that the storage requirement for an int is 4 bytes. I have always assumed that the displaylength (yeah, it is messy) is handled when data is retrieved.

[Anon]

Too confusing! So you guys said that int(10) is just the same as tinyint(10) ??? Is making int(10) a bad practice?