I need to know whether there is a performance issue when dealing with the database(database operations)depending on the datatype size of a particular field of a table. I have a table with a SMALLINT size primary key. But there is a chance of having a big data range than this data type can hold later.

I thought to allocate SMALLINT at the moment and later change it to MEDIUMINT depending on the required size. I thought to do this as I highly require the system to perform faster and because I thought datatype would affect the performance.

It's highly appreciated if someone could explain the relationship between datatype size and performance.

7 Years
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Last Post by chandimak

of course there is a differences in performance
but in my opinion, unless your application is really mission critical where second counts and u have hundred thousand of records and may be more than one hundred tables u don't need to be worried about performance



Even some database do not allow to change type especially when table having data, or it is key column.

In your case if it is PK then when u change PK's datatype you will also have to change datatype of its foreign key reference.

I suggest if it is going to cross SMALLINT range then better to use MEDIUMINT in the begining.

Edited by urtrivedi: n/a

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