sql primary key auto increment

Question

Is having a primary key that auto increments on each new row necessary? for me this number is getting quite long and I'm not even using it for anything.
I can imagine that with gradual user activity on my site new rows will be added (I am only testing atm with just 2 alfa test users and already the number has auto incremented to over 100), eventually this number could reach silly proportions (example: 10029379000577352881086) and not only slow the site down (effecting user experience) but also could inevitably push my site over its quota (exceeding its allowed size (laymen's))

really is this needed?

Answer 1

If you have some field/column (or combination of columns) which can be a primary key, use that, why use Auto increment. There are school of thoughts which believe using a mix of both. You could search for surrogate keys and you may find this answer interesting Surrogate vs. natural/business keys

For size quota problem, practically I don't think the maximum auto increment value would cause your site to go over data limit. If it is of int type it will take 4 bytes, regardless of the value inside. For SQL server int type could contain values ranging from -2^31 (-2,147,483,648) to 2^31-1 (2,147,483,647). Here is the link for that

Answer 2

You need a way to uniquely identify each record in your table.

If you have that already -- say a user-ID or email-address -- then you don't necessarily need that auto-incrementing field.

Note: If you don't already have a unique constraint on that field, you should add one so that duplicate data cannot be entered into the table.

Warning: If you decide to get rid of it, be sure that no other tables are using it.

Answer 3

can't you user multiple columns to get a composite key instead of that? just a hint.

Answer 4

You do need a key that identifies every row. But a key doesn't have to be a number that "auto-increments" for every row. The fact that a few people seem to think incrementing numbers are always a good idea for keys is probably a consequence either of carelessness or a lack of appreciation of database fundamentals, sound design and data integrity.

Answer 5

primary key is not always necessary to have for a table . for your question check my answer:

when and when not primary key should use