Ways to implement tags - pros and cons of each

Question

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Using SO as an example, what is the most sensible way to manage tags if you anticipate they will change often?

Way 1: Seriously denormalized (comma delim

Answer 1

Well I have the same doubt I adopted the third solution for my website. I know there is another way for dealing with this problem of variable-length tuples which consists in using columns as rows in this way you will have some information identifying the tuple redudant and the varying ones organized one for each row.

+--------+-------+-------------------------------------+
| postId | label | value                               | 
+--------+-------+-------------------------------------+
|   1    | tag   |C++                                  |
+--------+-------+-------------------------------------+
|   1    | tag   |search                               | 
+--------+-------+-------------------------------------+
|   1    | tag   |code                                 |
+--------+-------+-------------------------------------+
|   1    | title | Why is a raven like a writing desk? |
+--------+-------+-------------------------------------+ 

This is really bad but sometimes it's the only feasible solution, and it's very far from the relational approach.