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AvgAggregationWithLimit.java
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AvgAggregationWithLimit.java
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/*
* Copyright 2023 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.datastore.aggregation;
// [START datastore_avg_aggregation_query_with_limit]
import static com.google.cloud.datastore.aggregation.Aggregation.avg;
import com.google.cloud.datastore.AggregationQuery;
import com.google.cloud.datastore.AggregationResult;
import com.google.cloud.datastore.Datastore;
import com.google.cloud.datastore.DatastoreOptions;
import com.google.cloud.datastore.Entity;
import com.google.cloud.datastore.EntityQuery;
import com.google.cloud.datastore.Key;
import com.google.cloud.datastore.Query;
import com.google.common.collect.Iterables;
public class AvgAggregationWithLimit {
public static void invoke() {
// Instantiates a client.
Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
// The kind for the new entity.
String kind = "Sales";
Key sales1Key = datastore.newKeyFactory().setKind(kind).newKey("sales1");
Key sales2Key = datastore.newKeyFactory().setKind(kind).newKey("sales2");
Key sales3Key = datastore.newKeyFactory().setKind(kind).newKey("sales3");
// Save all the tasks.
datastore.put(
Entity.newBuilder(sales1Key).set("amount", 89).build(),
Entity.newBuilder(sales2Key).set("amount", 95).build(),
Entity.newBuilder(sales3Key).set("amount", 55).build());
EntityQuery selectAllSales = Query.newEntityQueryBuilder().setKind(kind).setLimit(2).build();
// Creating an aggregation query to get the avg of all sales amount.
AggregationQuery avgOfSalesQuery =
Query.newAggregationQueryBuilder()
.over(selectAllSales)
.addAggregation(avg("amount").as("at_least"))
.build();
// Executing aggregation query.
AggregationResult limitQueryResult =
Iterables.getOnlyElement(datastore.runAggregation(avgOfSalesQuery));
System.out.printf("Average with limit 2 is %d.", limitQueryResult.getLong("at_least")); // 72
}
}
// [END datastore_avg_aggregation_query_with_limit]