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spanner: Add snippets for ReadContext (#3662)
spanner: Add snippets for ReadContext
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‎google-cloud-clients/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ReadContext.java

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@@ -43,7 +43,18 @@ enum QueryAnalyzeMode {
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* to the first {@link ResultSet#next()} call. Regardless of blocking behavior, any {@link
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* SpannerException} is deferred to the first or subsequent {@link ResultSet#next()} call.
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*
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* <p>TODO(user): Code examples.
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* <!--SNIPPET read_context_read-->
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* <pre>{@code
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* ReadContext readContext = dbClient.singleUse();
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* ResultSet resultSet =
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* readContext.read(
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* "Albums",
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* // KeySet.all() can be used to read all rows in a table. KeySet exposes other
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* // methods to read only a subset of the table.
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* KeySet.all(),
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* Arrays.asList("SingerId", "AlbumId", "AlbumTitle"));
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* }</pre>
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* <!--SNIPPET read_context_read-->
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*
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* @param table the name of the table to read
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* @param keys the keys and ranges of rows to read. Regardless of ordering in {@code keys}, rows
@@ -61,6 +72,15 @@ enum QueryAnalyzeMode {
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* to the first {@link ResultSet#next()} call. Regardless of blocking behavior, any {@link
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* SpannerException} is deferred to the first or subsequent {@link ResultSet#next()} call.
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*
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* <!--SNIPPET read_context_read_index-->
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* <pre>{@code
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* ReadContext readContext = dbClient.singleUse();
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* Struct row =
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* readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
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* Arrays.asList("AlbumId", "AlbumTitle"));
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* }</pre>
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* <!--SNIPPET read_context_read_index-->
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*
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* @param table the name of the table to read
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* @param index the name of the index on {@code table} to use
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* @param keys the keys and ranges of index rows to read. Regardless of ordering in {@code keys},
@@ -74,6 +94,14 @@ ResultSet readUsingIndex(
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/**
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* Reads a single row from a database, returning {@code null} if the row does not exist.
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*
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* <!--SNIPPET read_context_read_row-->
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* <pre>{@code
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* ReadContext readContext = dbClient.singleUse();
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* Struct row =
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* readContext.readRow("Albums", Key.of(2, 1), Arrays.asList("MarketingBudget"));
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* }</pre>
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* <!--SNIPPET read_context_read_row-->
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*
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* @param table the name of the table to read
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* @param key the row to read
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* @param columns the columns to return
@@ -85,6 +113,15 @@ ResultSet readUsingIndex(
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* Reads a single row from a database using an index, returning {@code null} if the row does not
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* exist.
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*
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* <!--SNIPPET read_context_read_index-->
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* <pre>{@code
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* ReadContext readContext = dbClient.singleUse();
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* Struct row =
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* readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
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* Arrays.asList("AlbumId", "AlbumTitle"));
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* }</pre>
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* <!--SNIPPET read_context_read_index-->
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*
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* @param table the name of the table to read
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* @param index the name of the index on {@code table} to use
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* @param key the index row to read
@@ -101,6 +138,18 @@ ResultSet readUsingIndex(
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* is deferred to the first {@link ResultSet#next()} call. Regardless of blocking behavior, any
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* {@link SpannerException} is deferred to the first or subsequent {@link ResultSet#next()} call.
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*
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* <!--SNIPPET read_context_execute_query-->
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* <pre>{@code
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* // Rows without an explicit value for MarketingBudget will have a MarketingBudget equal to
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* // null.
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* ReadContext readContext = dbClient.singleUse();
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* ResultSet resultSet =
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* readContext.executeQuery(
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* Statement.of(
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* "SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime FROM Albums"));
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* }</pre>
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* <!--SNIPPET read_context_execute_query-->
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*
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* @param statement the query statement to execute
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* @param options the options to configure the query
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*/
@@ -113,6 +162,21 @@ ResultSet readUsingIndex(
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* com.google.spanner.v1.ResultSetStats} that can be accessed by calling {@link
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* ResultSet#getStats()} on the returned {@code ResultSet}.
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*
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* <!--SNIPPET read_context_analyze_query-->
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* <pre>{@code
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* ReadContext rc = dbClient.singleUse();
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* ResultSet resultSet =
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* rc.analyzeQuery(
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* Statement.of("SELECT SingerId, AlbumId, MarketingBudget FROM Albums"),
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* ReadContext.QueryAnalyzeMode.PROFILE);
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* while (resultSet.next()) {
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* // Discard the results. We're only processing because getStats() below requires it.
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* resultSet.getCurrentRowAsStruct();
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* }
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* ResultSetStats stats = resultSet.getStats();
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* }</pre>
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* <!--SNIPPET read_context_analyze_query-->
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*
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* @param statement the query statement to execute
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* @param queryMode the mode in which to execute the query
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*/

‎google-cloud-examples/src/main/java/com/google/cloud/examples/spanner/snippets/ReadContextSnippets.java

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@@ -0,0 +1,124 @@
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/*
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* Copyright 2018 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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/*
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* EDITING INSTRUCTIONS
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* This file is referenced in spanner/ReadContext's javadoc. Any change
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* to this file should be reflected in spanner/ReadContext's javadoc.
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*/
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package com.google.cloud.examples.spanner.snippets;
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import com.google.cloud.spanner.DatabaseClient;
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import com.google.cloud.spanner.Key;
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import com.google.cloud.spanner.KeySet;
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import com.google.cloud.spanner.ReadContext;
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import com.google.cloud.spanner.ResultSet;
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import com.google.cloud.spanner.Statement;
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import com.google.cloud.spanner.Struct;
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import com.google.spanner.v1.ResultSetStats;
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import java.util.Arrays;
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/**
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* This class contains snippets for {@link com.google.cloud.spanner.ReadContext} interface.
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*/
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public class ReadContextSnippets {
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private final DatabaseClient dbClient;
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public ReadContextSnippets(DatabaseClient dbClient) {
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this.dbClient = dbClient;
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}
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ResultSet read() {
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// [START read_context_read]
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ReadContext readContext = dbClient.singleUse();
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ResultSet resultSet =
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readContext.read(
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"Albums",
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// KeySet.all() can be used to read all rows in a table. KeySet exposes other
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// methods to read only a subset of the table.
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KeySet.all(),
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Arrays.asList("SingerId", "AlbumId", "AlbumTitle"));
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// [END read_context_read]
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return resultSet;
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}
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ResultSet readUsingIndex() {
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// [START read_context_read_index]
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ReadContext readContext = dbClient.singleUse();
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ResultSet resultSet =
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readContext.readUsingIndex(
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"Albums",
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"AlbumsByAlbumTitle",
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KeySet.all(),
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Arrays.asList("AlbumId", "AlbumTitle"));
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// [END read_context_read_index]
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return resultSet;
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}
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Struct readRow() {
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// [START read_context_read_row]
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ReadContext readContext = dbClient.singleUse();
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Struct row =
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readContext.readRow("Albums", Key.of(2, 1), Arrays.asList("MarketingBudget"));
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// [END read_context_read_row]
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return row;
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}
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Struct readRowUsingIndex() {
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// [START read_context_read_index]
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ReadContext readContext = dbClient.singleUse();
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Struct row =
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readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
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Arrays.asList("AlbumId", "AlbumTitle"));
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// [END read_context_read_index]
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return row;
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}
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ResultSet executeQuery() {
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// [START read_context_execute_query]
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// Rows without an explicit value for MarketingBudget will have a MarketingBudget equal to
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// null.
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ReadContext readContext = dbClient.singleUse();
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ResultSet resultSet =
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readContext.executeQuery(
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Statement.of(
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"SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime FROM Albums"));
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// [END read_context_execute_query]
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return resultSet;
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}
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ResultSetStats analyzeQuery() {
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// [START read_context_analyze_query]
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ReadContext rc = dbClient.singleUse();
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ResultSet resultSet =
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rc.analyzeQuery(
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Statement.of("SELECT SingerId, AlbumId, MarketingBudget FROM Albums"),
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ReadContext.QueryAnalyzeMode.PROFILE);
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while (resultSet.next()) {
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// Discard the results. We're only processing because getStats() below requires it.
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resultSet.getCurrentRowAsStruct();
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}
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ResultSetStats stats = resultSet.getStats();
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// [END read_context_analyze_query]
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return stats;
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}
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}
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