Menu
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?
796
In DynamoDB, each record in a table is uniquely identified by the primary key for your table. You can use this primary key to ensure there is not an existing record with the same primary key. To do so, you would use a Condition Expression to prevent writing an item if an item with the same key already exists.
However, the key values in a global secondary index do not need to be unique.
Unlike conventional relational databases, DynamoDB does not natively support a date and time data type. It can be useful instead to store data and time data as a number data type, using Unix epoch time.
A secondary index is a data structure that contains a subset of attributes from a table, along with an alternate key to support Query operations. You can retrieve data from the index using a Query , in much the same way as you use Query with a table.
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-mailTo ensure unicity, add a new table with this schema:
EmailUser
hash_key: e-mailuser_idTo 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.
107
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
