Azure CosmosDB Java SDK で 集計クエリー (Count) を使う

JavaSDK から CosmosDB で集計クエリーを利用するのにハマった点があったのでメモします。

クエリーにVALUE句を設定しないと以下のエラーになります。

java.lang.IllegalStateException: com.microsoft.azure.documentdb.DocumentClientException: Message: {"Errors":["Cross partition query only supports 'VALUE <AggreateFunc>' for aggregates."]}
Caused by: com.microsoft.azure.documentdb.DocumentClientException: Message: {"Errors":["Cross partition query only supports 'VALUE <AggreateFunc>' for aggregates."]}

また、setEnableCrossPartitionQuery を true にしないと以下のエラーになります。

java.lang.IllegalStateException: com.microsoft.azure.documentdb.DocumentClientException: Cross partition query is required but disabled. Please set x-ms-documentdb-query-enablecrosspartition to true, specify x-ms-documentdb-partitionkey, or revise your query to avoid this exception.
Caused by: com.microsoft.azure.documentdb.DocumentClientException: Cross partition query is required but disabled. Please set x-ms-documentdb-query-enablecrosspartition to true, specify x-ms-documentdb-partitionkey, or revise your query to avoid this exception.

以下、Javaのコードです。

		// Azure Cosmos DB Libraries for Java
		// https://docs.microsoft.com/ja-jp/java/api/overview/azure/cosmosdb?view=azure-java-stable

		String host = "yourhost";
		String container_id = "yourcontainer";
		String database = "yourdatabase";

		// Get key from Azure Web Console
		// read write key
		String key = "yourkey";

		String endPoint = "https://" + host + ".documents.azure.com:443";

		DocumentClient client = new DocumentClient(endPoint, key, //
				new ConnectionPolicy(), ConsistencyLevel.Session);

		String collectionLink = String.format("/dbs/%s/colls/%s", database, container_id);

		String q = String.format("SELECT VALUE count(1) FROM c");
		// IF (without 'VALUE' in query)
//		java.lang.IllegalStateException: com.microsoft.azure.documentdb.DocumentClientException: Message: {"Errors":["Cross partition query only supports 'VALUE <AggreateFunc>' for aggregates."]}
//		Caused by: com.microsoft.azure.documentdb.DocumentClientException: Message: {"Errors":["Cross partition query only supports 'VALUE <AggreateFunc>' for aggregates."]}

		FeedOptions feedOptions = new FeedOptions();
		feedOptions.setEnableCrossPartitionQuery(true);
		// IF (EnableCrossPartitionQuery = false)
//		java.lang.IllegalStateException: com.microsoft.azure.documentdb.DocumentClientException: Cross partition query is required but disabled. Please set x-ms-documentdb-query-enablecrosspartition to true, specify x-ms-documentdb-partitionkey, or revise your query to avoid this exception.
//		Caused by: com.microsoft.azure.documentdb.DocumentClientException: Cross partition query is required but disabled. Please set x-ms-documentdb-query-enablecrosspartition to true, specify x-ms-documentdb-partitionkey, or revise your query to avoid this exception.

		try {

			List<Object> results = client //
					.queryAggregateValues(collectionLink, q, feedOptions);

			System.err.println(results.get(0));

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			client.close();
		}

以上です。