What does each item in Cosmos DB statistics mean?

To collect the usage of each partition of Azure Cosmos DB, I ran the following command in the Azure CLI.

As a result, the following is returned as a response, but is there a document that describes the contents of each item?

In particular, I don't know what the item id in statistics means.

sh
$ az cosmosdb sql container show -n <container> -d <db> -a <account> -g <rg>



json
{
  "id": "/subscriptions/xxxx/resourceGroups/providers/Microsoft.DocumentDB/databaseAccounts/cosmos-account/sqlDatabases/test-db/tes-container",
  "location": null,
  "name": "test-container",
  "options": null,
  "resource": {
    "_conflicts": "conflicts/",
    "_docs": "docs/",
    "_sprocs": "sprocs/",
    "_triggers": "triggers/",
    "_udfs": "udfs/",
    "analyticalStorageTtl": null,
    "conflictResolutionPolicy": {
      "conflictResolutionPath": "/_ts",
      "conflictResolutionProcedure": "",
      "mode": "LastWriterWins"
    },
    "defaultTtl": null,
    "etag": "\"02000e57-0000-2300-0000-6168f37f0000\"",
    "geospatialConfig": {
      "type": "Geography"
    },
    "id": "test-cosmos-container",
    "indexingPolicy": {
      "automatic": true,
      "compositeIndexes": null,
      "excludedPaths": [
        {
          "path": "/\"_etag\"/?"
        }
      ],
      "includedPaths": [
        {
          "indexes": null,
          "path": "/*"
        }
      ],
      "indexingMode": "consistent",
      "spatialIndexes": null
    },
    "partitionKey": {
      "kind": "Hash",
      "paths": [
        "/partition-path"
      ],
      "systemKey": null,
      "version": null
    },
    "rid": "EpFgALliH9I=",
    "statistics": [
      {
        "documentCount": 189,
        "id": "0",
        "partitionKeys": [
          {
            "partitionKey": [],
            "sizeInKB": 7
          }
        ],
        "sizeInKB": 378
      }
    ],
    "ts": 1634268031.0,
    "uniqueKeyPolicy": {
      "uniqueKeys": []
    }
  },
  "resourceGroup": "rg",
  "tags": null,
  "type": "Microsoft.DocumentDB/databaseAccounts/sqlDatabases/containers"
}