Home/ Questions/Q 6924635
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-27T10:41:16+00:00

I want to handle a date dimension in a MySQL datawarehouse. (I m a

  • 0

I want to handle a date dimension in a MySQL datawarehouse. (I m a newbie in the DW world)

I made some searches with google and saw a lot of table structures (most of) date dimension where the Primary Key is a simple UNSIGNED INTEGER.

Why don’t use a DATE field as primary key since with MySQL it is 3 Bytes VS 4 Bytes for INTEGER?

Ex:

CREATE TABLE dimDate
id INTEGER UNSIGNED NOT NULL PRIMARY AUTOI_NCREMENT,
date DATE NOT NULL,
dayOfWeek
...

VS

CREATE TABLE dimDate
date DATE NOT NULL PRIMARY,
dayOfWeek
...
Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    If you have a table with a column that is of date type and where no two rows will ever have the same date, then you can surely use this column as PRIMARY KEY.

    You see a lot of examples where the Primary Key is a simple UNSIGNED INTEGER because there are many cases where there is no perfect candidate for Primary Key. The AUTO_INCREMENT allows this column to be automatically filled by the database (and be unique) during inserts .

    • 0