Updating CosmosDb indexing policy through ARM templates - azure-cosmosdb

Question

I am trying to use ARM templates to update the indexing policy for cosmos container. I tried 2 methods, one to simply declare the indexing policy in while declaring the container in ARM.
{
"apiVersion": "[variables('cosmosDbApiVersion')]",
"type": "Microsoft.DocumentDB/databaseAccounts/apis/databases/containers",
"dependsOn": [ /* resourceId */ ],
"name": "/* containerName */",
"properties": {
"resource": {
"id": "/* id */",
"partitionKey": {
"paths": [
"/partitionKey"
],
"kind": "Hash"
},
"indexes": [
{
"indexingMode": "consistent",
"automatic": true,
"includedPaths": [
{
"path": "/*",
"indexes": [
{
"kind": "Range",
"dataType": "Number",
"precision": -1
},
{
"kind": "Hash",
"dataType": "String",
"precision": 3
}
]
}
]
}
],
"defaultTtl": "[variables('defaultTtlValueToEnableTtl')]"
}
}
},
The second was to use to use ARM to deploy container setting as such:
{
"apiVersion": "[variables('cosmosDbApiVersion')]",
"type": "Microsoft.DocumentDB/databaseAccounts/apis/databases/containers/settings",
"name": "[/* name */",
"dependsOn": [ " /* container name */" ],
"properties": {
"resource": {
"throughput": "/* some throughput */",
"indexes": [
{
"indexingMode": "consistent",
"automatic": true,
"includedPaths": [
{
"path": "/*",
"indexes": [
{
"kind": "Range",
"dataType": "Number",
"precision": -1
},
{
"kind": "Hash",
"dataType": "String",
"precision": 3
}
]
}
]
}
]
}
}
},
Both techniques do not fail deployment but the indexing policy does not change.
Would appreciate some help.

Answer 1

this is the example from the template reference (looks slightly different to what you are doing):
"resource": {
"id": "string",
"indexingPolicy": {
"automatic": "boolean",
"indexingMode": "string",
"includedPaths": [
{
"path": "string",
"indexes": [
{
"dataType": "string",
"precision": "integer",
"kind": "string"
}
]
}
],
"excludedPaths": [
{
"path": "string"
}
],
"spatialIndexes": [
{
"path": "string",
"types": [
"string"
]
}
]
},
xxx
}
https://learn.microsoft.com/en-us/azure/templates/microsoft.documentdb/2019-08-01/databaseaccounts/sqldatabases/containers

Answer 2

Range and hash index types are ignored by the Cosmos resource provider now for new containers or containers that were created within the past year or so. ARM does not validate the index policy which is why the template will deploy successfully.
Hash index was deprecated for these newer container because the performance of the range index in the new indexer is surpasses what hash index provided so was no longer necessary.
To create/modify index policy refer to this article below. There are multiple examples of index policies that implement everything from very simple to more complex policies that include composite indexes, spatial indexes and unique keys.
https://learn.microsoft.com/en-us/azure/cosmos-db/manage-sql-with-resource-manager#create-resource