“Get” document from cosmosdb by id (not knowing the _rid)

Question

As MS Support recently told me that using a "GET" is much more efficient in RUs usage than a sql query. I'm wondering if I can (within the azure.cosmos python package or a custom HTTP request to the REST API) get a document by its unique 'id' field (for which I generated a GUIDs) without an SQL Query.

Every example shown are using the link/path of the doc which is built with the '_rid' metadata of the document and not the 'id' field set when creating the doc.

I use a bulk upsert stored procedure I wrote to create my new documents and never retrieve the metadata for each one of them (I have ~ 100 millions docs) so retrieving the _rid would be equivalent to retrieving the doc itself.

Answer 1

The reason that the ReadDocument method is so much more efficient than a SQL query is because it uses _rid instead of a user generated field, even the required id field. This is because the _rid isn't just a unique value, it also encodes information about where that document is physically stored.

To give an example of how this works, let's say you are explaining to someone where a party is this weekend. You could use the name that you use for the house "my friend Ryan's house" or you could use the address "123 ThatOne Street Somewhere, WA 11111". They both are unique identifiers, but for someone trying to get there one is way more efficient than the other.

Telling someone to go to your friend's house is like using your own id . It does map to a specific house, but the person will still need to find out where that physically is to get there. Using the address is like working with the _rid field. Based on that information alone they can get to the party location. Of course, in the real world the person would probably need directions, but the data storage in a database is a lot more organized than most city streets so an address is sufficient to go retrieve the document.

If you want to take advantage of this method you will need to find a way to work with the _rid field.