CODEWITHSUNDEEP
javadatabase-designgoogle-cloud-datastoreapp-engine-ndb
Pouton Gerald
Pouton Gerald

Reputation: 1625

How to add tagging to a database

Say I am working on a free for all blog where writers are allowed to tag their posts (basically twitter et all). How do I do that so that queries are optimized for speed?

I am thinking of having a tag field where the content is a list of tags

for example an entry may be an article about the president and the tags may be:

tag={politics, family, social, news, economy}

Notice that the tags are not predefined and that a writer adds them at whim/will.

Is my approach as described the best? Or is there a more efficient approach to doing this?

As it may matter, I am using the app-engine datastore and my language is java.

The ultimate objective is to allow users to search by specific tags, say a user wants to search by the tag "marriage".

Upvotes: 0

Views: 74

Answers (1)

Blake Hood
Blake Hood

Reputation: 314

First off, you probably do not want any field in a database to be a list of anything, as you typically want it to stay in third normal form at worst and having a column be a list of values violates first normal form.

The way that I've done tagging with small-scale projects (haven't tried anything large so I don't know for sure how scalable or not this would be) is to have a lookup table containing the tags, and a linking table containing the key for the thing to be tagged and the key for its tags.

So it would look something like this:

Thing                   Thing_Tags             Tags
------                  -----------            ----
ThingID (Guid)          ThingID (Guid)         TagID (Guid)
otherAttributes         TagID (Guid)           Tag (varchar)

Upvotes: 2

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