to be more specific, I’ve created a news module with a tag system. As each tag is unique (you are not allowed, as an admin, to create 2 identical tags), is the id column still useful? I guess no, but I was wondering about the performances.
id | mews_title | date … <————-> news_id | tag_id <———-> id | tag_name
VS
id | mews_title | date … <————-> news_id | tag_tag_name <———-> tag_name
Thanks a lot!
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Answer
The performance difference is insignificant.
Advantages to using a numeric id for the tags in your example would be:
- to make the intersection table somewhat smaller because integers are smaller on average than a string
- to allow changing the spelling of a tag name by updating one row instead of many rows
These may not be important considerations for your case. So no, it’s not required to use a numeric id.
I also wrote about this in a chapter titled “ID Required” in my book, SQL Antipatterns: Avoiding the Pitfalls of Database Programming.