Get all the Partition Keys in Azure Cosmos DB collection

Question

I have recently started using Azure Cosmos DB in our project. For the reporting purpose, we need to get all the Partition Keys in the collection. I could not find any suitable API to achieve it.

Answer 1

UPDATE: According to Brian in the comments below, DISTINCT is now supported. Try something like:

SELECT DISTINCT c.partitionKey FROM c

Prior answer: Idea that could work but for one thing...

The only way to get the actual partition key values is to do a unique aggregate on that field.

You can directly hit the REST endpoint at https://{your endpoint domain}.documents.azure.com/dbs/{your collection's uri fragment}/pkranges to pull back the minInclusive and maxExclusive ranges for each partition but those are hash space ranges and I don't know how to convert those into partition key values nor do a fanout using the actual minInclusive hash.

Also, there is a slim possibility that the pkranges can change between the time you retrieve them and the time you go to do something with them.