database schema - Use official identification card id or generated id's from MongoDB for identifying users? -

i designing schema simple mongodb database there collection customers.

natural way of identifying customer use official identification card id (6 numbers , letter, unique each person in country). way of doing letting mongodb choose _id field value , using card id field.

any suggestion of advantages / disadvantages of choosing 1 string 6 numbers , letter _id, or choosing , objectid created mongo?

uh, old "surrogate key vs. non-surrogate (natural) key" discussion. bit of flame war...

i think surrogate keys (i.e. objectids) way go. key objections "natural" key (the official id card id) these:

• you can't verify them. if user entered wrong number (but valid format), do? since primary keys can't changed, you'll have re-insert new object , fix links user. ugly.
• you have no control of them. if government decides re-issue number, you're out of luck
• their format can change on time, isn't big problem mongodb might problem in code / in api
• the natural key might expose information outside shall remain secret some/many users of system. suppose amazon use id card's number public identifier of account.

...and mongodb-specific argument

• the objectid has number of properties: carries timestamp , it's monotonic. natural keys can't make such guarantees