Is there a way to enforce unique constraint on a property (field) other than the primary key in dynamodb
amazon-dynamodb, unique-constraint
Solution
Short answer: No.
DynamoDB is a key:value store. It is very good at quickly retrieving/saving Items because it does a couple of compromise. This is a constraint you have to handle yourself.
Nonethess, depending on your actual model, it might be a good idea to use this field as you `hash_key` or consider using a `range_key`
If this is not possible, I advise you to de-normalize your data. You currently have something like:
`UserTable`
- `hash_key`: `user_id`
- `e-mail`
- ...
To ensure unicity, add a new table with this schema:
`EmailUser`
- `hash_key`: e-mail
- `user_id`
To make sure an e-mail is unique, just issue a `GetItem` to `EmailUser` before.
This kind of de-normalization is quite common with No-SQL databases.
Problem
In dynamodb, if you want to enforce uniqueness in a field other than the primary key (like were you have a users table and want unique email addresses for users while primary key is a userid which is a number) is there a way other thans scanning the table to see if the email is already in use?