DocumentDb: can multiple joins include empty sets - azure-cosmosdb

Question

I have a 'Message' collection in DocumentDb:
{
Subject: "Foo",
To: [
{ "Name": "Me", "Address": "me#company.com" }
],
Cc: [
{ "Name": "You", "Address": "you#company.com" }
]
}
and
{
Subject: "Bar",
To: [
{ "Name": "You", "Address": "you#company.com" }
],
Cc: []
}
I would like to select all documents that have 'you#company.com' as the To or Cc address:
SELECT Message.Subject
FROM Message
JOIN To IN Message.To
JOIN Cc IN Message.Cc
WHERE "you#company.com" IN (To.Address, Cc.Address)
This returns the first document, but not the second.
I believe the JOIN Cc in Message.Cc is causing the second document to be removed from the results because it is empty.
Is there a way I can structure the SQL query to include the second document in the result set?

Answer 1

No, this require two queries (You could write it in one query using a user-defined function, but that approach might not be able to use the index effectively).
SELECT Message.Subject
FROM Message
JOIN To IN Message.To
WHERE To.Address = "you#company.com"
SELECT Message.Subject
FROM Message
JOIN To IN Message.Cc
WHERE Cc.Address = "you#company.com"
Alternatively, if you have values for both Name and Value, you could write it as:
SELECT Message.Subject
FROM Message
WHERE ARRAY_CONTAINS(Message.To, { "Name": "You", "Address": "you#company.com" })
OR ARRAY_CONTAINS(Message.Cc, { "Name": "You", "Address": "you#company.com" })
If you'd like to see this added to DocumentDB's query, please support/upvote support for sub-queries at https://feedback.azure.com/forums/263030-documentdb/.