Cosmo DB Mongo Collection Order of compound index matters or not

[yupwei68]

request:
{
"parameters": {
"accountName": "ddb1",
"resourceGroupName": "rg1",
"api-version": "2020-04-01",
"subscriptionId": "subid",
"databaseName": "databaseName",
"collectionName": "collectionName",
"createUpdateMongoDBCollectionParameters": {
"location": "West US",
"tags": {},
"properties": {
"resource": {
"id": "collectionName",
"indexes": [
{
"key": {
"keys": ["testKey" ] <<- Here whether the order of the keys matters
},
"options": {
"expireAfterSeconds": 100,
"unique": true
}
}
],
...
},
"options": {}
}
}
},

[yupwei68]

@MehaKaushik Could you please support us on this question?

[ghost]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @wmengmsft, @MehaKaushik, @shurd, @anfeldma-ms.

[MehaKaushik]

@yupwei68 MongoDB API for CosmosDB follows the same rules as for the MongoDB.

Referencing this https://docs.mongodb.com/manual/core/index-compound/.
"The order of the fields listed in a compound index is important. The index will contain references to documents sorted first by the values of the item field and, within each value of the item field, sorted by values of the stock field. See Sort Order for more information."

To summarize: the order will matter.

[yupwei68]

Thanks @MehaKaushik !