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samples: Add sample snippets for count aggregations (#871)
* Add method in Datastore client to invoke rpc for aggregation query * Creating count aggregation and using it to populate Aggregation proto * Moving aggregation builder method to root level aggregation class * Introducing RecordQuery to represent queries which returns entity records when executed * Updating gitignore with patch extension * Setting up structure of Aggregation query and its builder * Introducing ProtoPreparer to populate the request protos * Delegating responsibility of preparing query proto to QueryPreparer * Populating aggregation query with nested structured query * Delegating responsibility of preparing query proto in GqlQuery to QueryPreparer * Removing RecordQuery from the query hierarchy and making it a standalone interface for now * Populating aggregation query with nested gql query * Removing deprecation warning by using assertThrows instead of ExpectedException rule * Making DatastoreRpc call aggregation query method on client * Creating response transformer to transform aggregation query response into domain objects * Implementing aggregation query executor to execute AggergationQuery * Adding missing assertion statements * Creating RetryExecutor to inject it as a dependency in other components * Making RetryExecutor accept RetrySettings when creating it * Revert "Making RetryExecutor accept RetrySettings when creating it" This reverts commit 1dfafb7. * Revert "Creating RetryExecutor to inject it as a dependency in other components" This reverts commit 8872a55. * Introducing RetryAndTraceDatastoreRpcDecorator to have retry and traceability logic on top of another DatastoreRpc * Extracting out the responsibility of preparing ReadOption in it's own ProtoPreparer * Making QueryExecutor to execute query with provided ReadOptions * Exposing readTime to the user * Ignoring runAggregationQuery method from clirr check * Making readTime final * Allowing namespace to be optional in AggregationQuery * Add capability to fetch aggregation result by passing alias * Implementing User facing datastore.runAggrgation method to run aggregation query * Add integration test for count aggregation * Add transaction Id support in ReadOptionsProtoPreparer * Supporting aggregation query with transactions * Allowing user to create Aggregation directly without involving its builder * Preventing creating duplicated aggregation when creating an aggregation query * Marking RecordQuery implemented method as InternalApi * Writing comments and JavaDoc for aggregation query related class * Adding a default implementation in the public interfaces to avoid compile time failures * covering a scenario to maintain consistent snapshot when executing aggregation query in a transaction * Creating emulator proxy to simulate AggregationQuery response from emulator * Integration test to execute an aggregation query in a read only transaction * Count aggregation samples with structuredQuery and gql query * Count aggregation samples to demonstrate stale read * Getting rid off limit operation on count aggregation as same behaviour can be achieved by using 'limit' operation on the underlying query * Removing import statement from javadoc and undo changes in .gitignore file * Using Optional instead of returning null from ReadOptionsProtoPreparer * using assertThat from Truth library * Removing 'limit' api from count query samples * fixing unit test * Getting rid off Double braces initialization syntax * Fixing lint * Getting rid off emulator proxy and using easy mock to check the aggregationQuery triggered * Deleting a entity created locally in other test which is causing failure in other test * Deleting all keys in datastore in integration test so that new test can start fresh * Executing two read write transaction simultaneously and verifying their behaviour * Removing tests to verify serializability as it's an underlying implementation detail * Fixing lint * Adding runAggregationQuery method to reflect config so that it's available and accessible in native image through reflection * Aggregation query samples with limit and order by option * Aggregation query samples with transactions * fixing lint and reusing sysoutRule * correcting region tag * simplifying tearDown method * Reverting back to using Task domain for aggregation query samples * Limiting tearDown method to delete only Task entities * Splitting count aggregation query samples into individual java files * 🦉 Updates from OwlBot post-processor See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md * Adding missing header * Sticking to the practise of deleting the old created data in setUp of test * Moving comment to the top of statement. Co-authored-by: Sita Lakshmi Sangameswaran <[email protected]> * Making builder syntax multiline Co-authored-by: Sita Lakshmi Sangameswaran <[email protected]> * Adding comment describing the purpose of GQL query Co-authored-by: Sita Lakshmi Sangameswaran <[email protected]> * Rephrasing the comment Co-authored-by: Sita Lakshmi Sangameswaran <[email protected]> * Adding a comment describing the purpose of the GQL query Co-authored-by: Sita Lakshmi Sangameswaran <[email protected]> * Rephrasing the comment Co-authored-by: Sita Lakshmi Sangameswaran <[email protected]> * Relocating region tags to include import statments * Few styling and comment fixes * Adding comment in the transaction block * Adding fullstop to the comment lines * Showcasing with/without alias usage separately * Importing static methods are we are now including import statements in samples * 🦉 Updates from OwlBot post-processor See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com> Co-authored-by: Sita Lakshmi Sangameswaran <[email protected]>
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‎README.md‎

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@@ -234,6 +234,13 @@ Samples are in the [`samples/`](https://github.com/googleapis/java-datastore/tre
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| --------------------------- | --------------------------------- | ------ |
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| Native Image Datastore Sample | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/native-image-sample/src/main/java/com/example/datastore/NativeImageDatastoreSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/native-image-sample/src/main/java/com/example/datastore/NativeImageDatastoreSample.java) |
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| Quickstart Sample | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/QuickstartSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/QuickstartSample.java) |
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| Count Aggregation In Transaction | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationInTransaction.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationInTransaction.java) |
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| Count Aggregation On Kind | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationOnKind.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationOnKind.java) |
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| Count Aggregation With Gql Query | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithGqlQuery.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithGqlQuery.java) |
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| Count Aggregation With Limit | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithLimit.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithLimit.java) |
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| Count Aggregation With Order By | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithOrderBy.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithOrderBy.java) |
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| Count Aggregation With Property Filter | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithPropertyFilter.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithPropertyFilter.java) |
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| Count Aggregation With Stale Read | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithStaleRead.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithStaleRead.java) |
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| Task List | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/google/datastore/snippets/TaskList.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/google/datastore/snippets/TaskList.java) |
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‎samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationInTransaction.java‎

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/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.datastore.aggregation;
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// [START datastore_count_aggregation_query_in_transaction]
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import static com.google.cloud.datastore.aggregation.Aggregation.count;
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import com.google.cloud.datastore.AggregationQuery;
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import com.google.cloud.datastore.Datastore;
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import com.google.cloud.datastore.Datastore.TransactionCallable;
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import com.google.cloud.datastore.DatastoreOptions;
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import com.google.cloud.datastore.Entity;
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import com.google.cloud.datastore.EntityQuery;
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import com.google.cloud.datastore.Key;
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import com.google.cloud.datastore.Query;
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import com.google.cloud.datastore.StructuredQuery.PropertyFilter;
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import com.google.common.collect.Iterables;
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public class CountAggregationInTransaction {
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public static void invoke() {
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// Instantiates a client.
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Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
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// The kind for the new entity.
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String kind = "Task";
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Key task1Key = datastore.newKeyFactory().setKind(kind).newKey("task1");
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Key task2Key = datastore.newKeyFactory().setKind(kind).newKey("task2");
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// Save all the tasks.
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datastore.put(
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Entity.newBuilder(task1Key).set("owner", "john").build(),
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Entity.newBuilder(task2Key).set("owner", "john").build());
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// Using transactions to maintain consistent application state.
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datastore.runInTransaction(
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(TransactionCallable<Void>)
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transaction -> {
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// Create a query to get the count of all tasks of owner 'John'.
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EntityQuery tasksOfJohn =
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Query.newEntityQueryBuilder()
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.setKind(kind)
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.setFilter(PropertyFilter.eq("owner", "john"))
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.build();
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AggregationQuery totalTasksQuery =
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Query.newAggregationQueryBuilder()
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.over(tasksOfJohn)
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.addAggregation(count().as("tasks_count"))
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.build();
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// Executing aggregation query in the ongoing transaction.
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Long tasksCount =
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Iterables.getOnlyElement(transaction.runAggregation(totalTasksQuery))
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.get("tasks_count");
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if (tasksCount < 2) {
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Key newTaskKey = datastore.newKeyFactory().setKind(kind).newKey("task3");
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Entity newTask = Entity.newBuilder(newTaskKey).set("owner", "john").build();
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// Inserting a new entity in the transaction.
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transaction.put(newTask);
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} else {
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System.out.printf("Found existing %d tasks, rolling back", tasksCount);
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throw new Exception("User 'John' cannot have more than 2 tasks");
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}
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return null;
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});
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}
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}
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// [END datastore_count_aggregation_query_in_transaction]

‎samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationOnKind.java‎

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/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.datastore.aggregation;
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// [START datastore_count_aggregation_query_on_kind]
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import static com.google.cloud.datastore.aggregation.Aggregation.count;
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import com.google.cloud.datastore.AggregationQuery;
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import com.google.cloud.datastore.AggregationResult;
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import com.google.cloud.datastore.Datastore;
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import com.google.cloud.datastore.DatastoreOptions;
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import com.google.cloud.datastore.Entity;
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import com.google.cloud.datastore.EntityQuery;
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import com.google.cloud.datastore.Key;
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import com.google.cloud.datastore.Query;
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import com.google.common.collect.Iterables;
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public class CountAggregationOnKind {
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// Instantiates a client.
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private static final Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
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// The kind for the new entity.
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private static final String kind = "Task";
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// Setting up Tasks in database
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private static void setUpTasks() {
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Key task1Key = datastore.newKeyFactory().setKind(kind).newKey("task1");
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Key task2Key = datastore.newKeyFactory().setKind(kind).newKey("task2");
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Key task3Key = datastore.newKeyFactory().setKind(kind).newKey("task3");
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// Save all the tasks.
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datastore.put(
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Entity.newBuilder(task1Key).set("done", true).build(),
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Entity.newBuilder(task2Key).set("done", false).build(),
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Entity.newBuilder(task3Key).set("done", true).build());
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}
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// Accessing aggregation result by the generated alias.
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private static void usageWithGeneratedAlias() {
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EntityQuery selectAllTasks = Query.newEntityQueryBuilder().setKind(kind).build();
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// Creating an aggregation query to get the count of all tasks.
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AggregationQuery allTasksCountQuery =
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Query.newAggregationQueryBuilder().over(selectAllTasks).addAggregation(count()).build();
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// Executing aggregation query.
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AggregationResult aggregationResult =
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Iterables.getOnlyElement(datastore.runAggregation(allTasksCountQuery));
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System.out.printf(
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"Total tasks (accessible from default alias) is %d",
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aggregationResult.get("property_1")); // 3
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}
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// Accessing aggregation result by the provided custom alias.
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private static void usageWithCustomAlias() {
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EntityQuery selectAllTasks = Query.newEntityQueryBuilder().setKind(kind).build();
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// Creating an aggregation query to get the count of all tasks.
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AggregationQuery allTasksCountQuery =
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Query.newAggregationQueryBuilder()
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.over(selectAllTasks)
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// passing 'total_count' as alias in the aggregation query.
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.addAggregation(count().as("total_count"))
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.build();
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// Executing aggregation query.
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AggregationResult aggregationResult =
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Iterables.getOnlyElement(datastore.runAggregation(allTasksCountQuery));
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System.out.printf("Total tasks count is %d", aggregationResult.get("total_count")); // 3
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}
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public static void invoke() {
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setUpTasks();
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usageWithGeneratedAlias();
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usageWithCustomAlias();
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}
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}
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// [END datastore_count_aggregation_query_on_kind]

‎samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithGqlQuery.java‎

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/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.datastore.aggregation;
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// [START datastore_count_aggregation_query_gql]
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import com.google.cloud.datastore.AggregationQuery;
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import com.google.cloud.datastore.AggregationResult;
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import com.google.cloud.datastore.Datastore;
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import com.google.cloud.datastore.DatastoreOptions;
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import com.google.cloud.datastore.Entity;
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import com.google.cloud.datastore.GqlQuery;
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import com.google.cloud.datastore.Key;
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import com.google.cloud.datastore.Query;
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import com.google.common.collect.Iterables;
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public class CountAggregationWithGqlQuery {
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public static void invoke() {
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// Instantiates a client.
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Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
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// The kind for the new entity.
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String kind = "Task";
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Key task1Key = datastore.newKeyFactory().setKind(kind).newKey("task1");
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Key task2Key = datastore.newKeyFactory().setKind(kind).newKey("task2");
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Key task3Key = datastore.newKeyFactory().setKind(kind).newKey("task3");
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// Save all the tasks.
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datastore.put(
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Entity.newBuilder(task1Key).set("done", true).build(),
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Entity.newBuilder(task2Key).set("done", false).build(),
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Entity.newBuilder(task3Key).set("done", true).build());
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// Create a GQL query to get the count of all tasks.
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GqlQuery<?> selectAllTasks =
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Query.newGqlQueryBuilder(
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"AGGREGATE COUNT(*) AS total_count, COUNT_UP_TO(2) AS count_with_limit "
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+ "OVER (SELECT * FROM Task)")
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.setAllowLiteral(true)
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.build();
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// Create the aggregation query builder and set the query.
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AggregationQuery allTasksCountQuery =
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Query.newAggregationQueryBuilder().over(selectAllTasks).build();
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// Executing aggregation query.
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AggregationResult allTasksCountQueryResult =
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Iterables.getOnlyElement(datastore.runAggregation(allTasksCountQuery));
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System.out.printf(
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"We have at least %d tasks", allTasksCountQueryResult.get("count_with_limit")); // 2
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System.out.printf("Total tasks count is %d", allTasksCountQueryResult.get("total_count")); // 3
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// Create a query to get the count of all completed tasks.
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GqlQuery<?> completedTasks =
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Query.newGqlQueryBuilder(
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"AGGREGATE COUNT(*) AS total_completed_count "
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+ "OVER (SELECT * FROM Task WHERE done = true)")
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.setAllowLiteral(true)
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.build();
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// Create the aggregation query builder and set the query.
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AggregationQuery completedTasksCountQuery =
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Query.newAggregationQueryBuilder().over(completedTasks).build();
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// Executing aggregation query.
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AggregationResult completedTasksCountQueryResult =
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Iterables.getOnlyElement(datastore.runAggregation(completedTasksCountQuery));
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System.out.printf(
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"Total completed tasks count is %d",
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completedTasksCountQueryResult.get("total_completed_count")); // 2
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}
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}
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// [END datastore_count_aggregation_query_gql]

‎samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithLimit.java‎

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/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.datastore.aggregation;
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// [START datastore_count_aggregation_query_with_limit]
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import static com.google.cloud.datastore.aggregation.Aggregation.count;
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import com.google.cloud.datastore.AggregationQuery;
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import com.google.cloud.datastore.AggregationResult;
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import com.google.cloud.datastore.Datastore;
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import com.google.cloud.datastore.DatastoreOptions;
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import com.google.cloud.datastore.Entity;
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import com.google.cloud.datastore.EntityQuery;
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import com.google.cloud.datastore.Key;
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import com.google.cloud.datastore.Query;
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import com.google.common.collect.Iterables;
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public class CountAggregationWithLimit {
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public static void invoke() {
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// Instantiates a client.
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Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
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// The kind for the new entity.
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String kind = "Task";
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Key task1Key = datastore.newKeyFactory().setKind(kind).newKey("task1");
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Key task2Key = datastore.newKeyFactory().setKind(kind).newKey("task2");
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Key task3Key = datastore.newKeyFactory().setKind(kind).newKey("task3");
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// Save all the tasks.
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datastore.put(
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Entity.newBuilder(task1Key).set("done", true).build(),
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Entity.newBuilder(task2Key).set("done", false).build(),
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Entity.newBuilder(task3Key).set("done", true).build());
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EntityQuery selectAllTasks = Query.newEntityQueryBuilder().setKind(kind).setLimit(2).build();
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// Creating an aggregation query to get the count of all tasks.
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AggregationQuery allTasksCountQuery =
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Query.newAggregationQueryBuilder()
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.over(selectAllTasks)
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.addAggregation(count().as("at_least"))
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.build();
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// Executing aggregation query.
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AggregationResult limitQueryResult =
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Iterables.getOnlyElement(datastore.runAggregation(allTasksCountQuery));
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System.out.printf("We have at least %d tasks", limitQueryResult.get("at_least")); // 2
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}
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}
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// [END datastore_count_aggregation_query_with_limit]

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