Dear Kettlers,
A couple of years ago I wrote a post about key/value tables and how they can ruin the day of any honest person that wants to create BI solutions. The obvious advice I gave back then was to not use those tables in the first place if you’re serious about a BI solution. And if you have to, do some denormalization.
However, there are occasions where you need to query a source system and get some report going on them. Let’s take a look at an example :
mysql> select * from person; +----+-------+----------+ | id | name | lastname | +----+-------+----------+ | 1 | Lex | Luthor | | 2 | Clark | Kent | | 3 | Lois | Lane | +----+-------+----------+ 3 rows in set (0.00 sec) mysql> select * from person_attribute; +----+-----------+---------------+------------+ | id | person_id | attr_key | attr_value | …[Read more]