Group by multiple properties in Cosmos DB - azure-cosmosdb

Question

I have the following collection (c) and I want to group a specific property into a list of values, by multiple properties.
{
"trim": "8375",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": "9854",
"year": "2022",
"model_name": "NX Hybrid",
"brand": "LEXUS"
},
{
"trim": "8361",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": "8382",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": "9854",
"year": "2022",
"model_name": "NX Hybrid",
"brand": "LEXUS"
},
{
"trim": "8386",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": "9764",
"year": "2022",
"model_name": "NX Hybrid",
"brand": "LEXUS"
},
{
"trim": "8361",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": "8261",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": "8376",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": "8361",
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
}
The properties by which I want to group by are the year, model_name and brand. I want to store the trim in a list containing unique trims only.
Result should look like:
{
"trim": ["8375", "8361", "8382", "8386", "8261", "8376"],
"year": "2022",
"model_name": "Tundra",
"brand": "TOYOTA"
},
{
"trim": ["9854", "9764"],
"year": "2022",
"model_name": "NX Hybrid",
"brand": "LEXUS"
},

Answer 1

From group by documentation:
When a query uses a GROUP BY clause, the SELECT clause can only contain the subset of properties and system functions included in the GROUP BY clause. One exception is aggregate functions, which can appear in the SELECT clause without being included in the GROUP BY clause.
Aggregation function documentation does not mention any aggregation function for concatenating arrays.
So, your intended query cannot currently be implemented just by SQL query.
What you can do instead (depending on expected data amounts and acceptable RU usage):
query without grouping and apply grouping in client,
-or- query without array and make separate N queries to get trim numbers per each group.