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docs: Add snippet for ReadLockMode configuration at client and transaction
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-49
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‎samples/snippets/pom.xml‎

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@@ -34,7 +34,7 @@
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<dependency>
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<groupId>com.google.cloud</groupId>
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<artifactId>libraries-bom</artifactId>
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<version>26.72.0</version>
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<version>26.73.0</version>
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<type>pom</type>
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<scope>import</scope>
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</dependency>

‎samples/snippets/src/main/java/com/example/spanner/IsolationLevelAndReadLockModeSample.java‎

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/*
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* Copyright 2026 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.spanner;
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import com.google.cloud.spanner.DatabaseClient;
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import com.google.cloud.spanner.DatabaseId;
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import com.google.cloud.spanner.Options;
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import com.google.cloud.spanner.ResultSet;
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import com.google.cloud.spanner.Spanner;
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import com.google.cloud.spanner.SpannerOptions;
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import com.google.cloud.spanner.SpannerOptions.Builder.DefaultReadWriteTransactionOptions;
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import com.google.cloud.spanner.Statement;
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import com.google.spanner.v1.TransactionOptions.IsolationLevel;
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import com.google.spanner.v1.TransactionOptions.ReadWrite.ReadLockMode;
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public class IsolationLevelAndReadLockModeSample {
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// [START spanner_isolation_level]
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static void isolationLevelSetting(DatabaseId db) {
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// The isolation level specified at the client-level will be applied to all
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// RW transactions.
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DefaultReadWriteTransactionOptions transactionOptions =
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DefaultReadWriteTransactionOptions.newBuilder()
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.setIsolationLevel(IsolationLevel.SERIALIZABLE)
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.build();
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SpannerOptions options =
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SpannerOptions.newBuilder()
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.setDefaultTransactionOptions(transactionOptions)
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.build();
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Spanner spanner = options.getService();
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DatabaseClient dbClient = spanner.getDatabaseClient(db);
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dbClient
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// The isolation level specified at the transaction-level takes precedence
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// over the isolation level configured at the client-level.
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.readWriteTransaction(Options.isolationLevel(IsolationLevel.REPEATABLE_READ))
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.run(transaction -> {
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// Read an AlbumTitle.
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String selectSql =
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"SELECT AlbumTitle from Albums WHERE SingerId = 1 and AlbumId = 1";
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String title = null;
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try (ResultSet resultSet = transaction.executeQuery(Statement.of(selectSql))) {
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if (resultSet.next()) {
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title = resultSet.getString("AlbumTitle");
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}
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}
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System.out.printf("Current album title: %s\n", title);
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// Update the title.
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String updateSql =
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"UPDATE Albums "
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+ "SET AlbumTitle = 'New Album Title' "
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+ "WHERE SingerId = 1 and AlbumId = 1";
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long rowCount = transaction.executeUpdate(Statement.of(updateSql));
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System.out.printf("%d record updated.\n", rowCount);
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return null;
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});
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}
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// [END spanner_isolation_level]
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// [START spanner_read_lock_mode]
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static void readLockModeSetting(DatabaseId db) {
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// The read lock mode specified at the client-level will be applied to all
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// RW transactions.
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DefaultReadWriteTransactionOptions transactionOptions =
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DefaultReadWriteTransactionOptions.newBuilder()
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.setReadLockMode(ReadLockMode.OPTIMISTIC)
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.build();
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SpannerOptions options =
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SpannerOptions.newBuilder()
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.setDefaultTransactionOptions(transactionOptions)
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.build();
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Spanner spanner = options.getService();
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DatabaseClient dbClient = spanner.getDatabaseClient(db);
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dbClient
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// The read lock mode specified at the transaction-level takes precedence
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// over the read lock mode configured at the client-level.
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.readWriteTransaction(Options.readLockMode(ReadLockMode.PESSIMISTIC))
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.run(transaction -> {
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// Read an AlbumTitle.
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String selectSql =
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"SELECT AlbumTitle from Albums WHERE SingerId = 1 and AlbumId = 1";
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String title = null;
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try (ResultSet resultSet = transaction.executeQuery(Statement.of(selectSql))) {
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if (resultSet.next()) {
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title = resultSet.getString("AlbumTitle");
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}
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}
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System.out.printf("Current album title: %s\n", title);
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// Update the title.
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String updateSql =
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"UPDATE Albums "
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+ "SET AlbumTitle = 'New Album Title' "
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+ "WHERE SingerId = 1 and AlbumId = 1";
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long rowCount = transaction.executeUpdate(Statement.of(updateSql));
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System.out.printf("%d record updated.\n", rowCount);
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return null;
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});
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}
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// [END spanner_read_lock_mode]
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}

‎samples/snippets/src/main/java/com/example/spanner/SpannerSample.java‎

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@@ -32,15 +32,13 @@
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import com.google.cloud.spanner.KeyRange;
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import com.google.cloud.spanner.KeySet;
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import com.google.cloud.spanner.Mutation;
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import com.google.cloud.spanner.Options;
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import com.google.cloud.spanner.ReadOnlyTransaction;
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import com.google.cloud.spanner.ResultSet;
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import com.google.cloud.spanner.Spanner;
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import com.google.cloud.spanner.SpannerBatchUpdateException;
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import com.google.cloud.spanner.SpannerException;
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import com.google.cloud.spanner.SpannerExceptionFactory;
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import com.google.cloud.spanner.SpannerOptions;
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import com.google.cloud.spanner.SpannerOptions.Builder.DefaultReadWriteTransactionOptions;
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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.cloud.spanner.TimestampBound;
@@ -73,7 +71,6 @@
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import com.google.spanner.admin.database.v1.RestoreDatabaseRequest;
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import com.google.spanner.admin.database.v1.RestoreInfo;
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import com.google.spanner.v1.ExecuteSqlRequest.QueryOptions;
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import com.google.spanner.v1.TransactionOptions.IsolationLevel;
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import java.math.BigDecimal;
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import java.time.Instant;
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import java.time.ZoneId;
@@ -1555,47 +1552,6 @@ static void queryWithQueryOptions(DatabaseClient dbClient) {
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}
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// [END spanner_query_with_query_options]
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// [START spanner_isolation_level]
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static void isolationLevelSetting(DatabaseId db) {
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// The isolation level specified at the client-level will be applied to all
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// RW transactions.
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DefaultReadWriteTransactionOptions transactionOptions =
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DefaultReadWriteTransactionOptions.newBuilder()
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.setIsolationLevel(IsolationLevel.SERIALIZABLE)
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.build();
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SpannerOptions options =
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SpannerOptions.newBuilder()
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.setDefaultTransactionOptions(transactionOptions)
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.build();
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Spanner spanner = options.getService();
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DatabaseClient dbClient = spanner.getDatabaseClient(db);
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dbClient
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// The isolation level specified at the transaction-level takes precedence
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// over the isolation level configured at the client-level.
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.readWriteTransaction(Options.isolationLevel(IsolationLevel.REPEATABLE_READ))
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.run(transaction -> {
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// Read an AlbumTitle.
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String selectSql =
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"SELECT AlbumTitle from Albums WHERE SingerId = 1 and AlbumId = 1";
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ResultSet resultSet = transaction.executeQuery(Statement.of(selectSql));
1581-
String title = null;
1582-
while (resultSet.next()) {
1583-
title = resultSet.getString("AlbumTitle");
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}
1585-
System.out.printf("Current album title: %s\n", title);
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// Update the title.
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String updateSql =
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"UPDATE Albums "
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+ "SET AlbumTitle = 'New Album Title' "
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+ "WHERE SingerId = 1 and AlbumId = 1";
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long rowCount = transaction.executeUpdate(Statement.of(updateSql));
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System.out.printf("%d record updated.\n", rowCount);
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return null;
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});
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}
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// [END spanner_isolation_level]
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// [START spanner_create_backup]
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static void createBackup(DatabaseAdminClient dbAdminClient, String projectId, String instanceId,
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String databaseId, String backupId, Timestamp versionTime) {
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case "querywithqueryoptions":
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queryWithQueryOptions(dbClient);
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break;
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case "isolationlevelsettings":
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isolationLevelSetting(database);
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break;
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case "createbackup":
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createBackup(dbAdminClient, database.getInstanceId().getProject(),
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database.getInstanceId().getInstance(), database.getDatabase(),
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System.err.println(" SpannerExample querywithtimestampparameter my-instance example-db");
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System.err.println(" SpannerExample clientwithqueryoptions my-instance example-db");
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System.err.println(" SpannerExample querywithqueryoptions my-instance example-db");
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System.err.println(" SpannerExample isolationlevelsettings my-instance example-db");
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System.err.println(" SpannerExample createbackup my-instance example-db");
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System.err.println(" SpannerExample listbackups my-instance example-db");
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System.err.println(" SpannerExample listbackupoperations my-instance example-db backup-id");

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