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docs: Add snippet for ReadLockMode configuration at client and transaction (#4305)
* docs: Add snippet for ReadLockMode configuration at client and transaction * read write IT using txn options * updated README with the sample link
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‎README.md‎

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@@ -374,6 +374,7 @@ Samples are in the [`samples/`](https://github.com/googleapis/java-spanner/tree/
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| Get Database Ddl Sample | [source code](https://github.com/googleapis/java-spanner/blob/main/samples/snippets/src/main/java/com/example/spanner/GetDatabaseDdlSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/GetDatabaseDdlSample.java) |
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| Get Instance Config Sample | [source code](https://github.com/googleapis/java-spanner/blob/main/samples/snippets/src/main/java/com/example/spanner/GetInstanceConfigSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/GetInstanceConfigSample.java) |
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| Insert Using Dml Returning Sample | [source code](https://github.com/googleapis/java-spanner/blob/main/samples/snippets/src/main/java/com/example/spanner/InsertUsingDmlReturningSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/InsertUsingDmlReturningSample.java) |
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| Isolation Level and Read Lock Mode Sample | [source code](https://github.com/googleapis/java-spanner/blob/main/samples/snippets/src/main/java/com/example/spanner/IsolationLevelAndReadLockModeSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/IsolationLevelAndReadLockModeSample.java) |
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| Last Statement Sample | [source code](https://github.com/googleapis/java-spanner/blob/main/samples/snippets/src/main/java/com/example/spanner/LastStatementSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/LastStatementSample.java) |
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| List Backup Schedules Sample | [source code](https://github.com/googleapis/java-spanner/blob/main/samples/snippets/src/main/java/com/example/spanner/ListBackupSchedulesSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/ListBackupSchedulesSample.java) |
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| List Database Roles | [source code](https://github.com/googleapis/java-spanner/blob/main/samples/snippets/src/main/java/com/example/spanner/ListDatabaseRoles.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/ListDatabaseRoles.java) |

‎google-cloud-spanner/src/test/java/com/google/cloud/spanner/it/ITTransactionTest.java‎

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@@ -41,7 +41,10 @@
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import com.google.cloud.spanner.ReadContext;
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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.SpannerException;
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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;
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import com.google.common.collect.Sets;
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import com.google.common.util.concurrent.SettableFuture;
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import com.google.common.util.concurrent.Uninterruptibles;
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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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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
@@ -213,6 +218,54 @@ public void basicsUsingQuery() throws InterruptedException {
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});
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}
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@Test
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public void isolationLevelAndReadLockModeSetAtClientLevelTest() {
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SpannerOptions options =
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env.getTestHelper().getOptions().toBuilder()
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.setDefaultTransactionOptions(
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DefaultReadWriteTransactionOptions.newBuilder()
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.setIsolationLevel(IsolationLevel.REPEATABLE_READ)
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.setReadLockMode(ReadLockMode.OPTIMISTIC)
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.build())
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.build();
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try (Spanner spanner = options.getService()) {
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DatabaseClient client = spanner.getDatabaseClient(db.getId());
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Long updatedRows =
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client
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.readWriteTransaction()
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.run(
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transaction ->
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transaction.executeUpdate(
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Statement.of("INSERT INTO T (K, V) VALUES ('test1', 2)")));
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assertThat(updatedRows).isEqualTo(1L);
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}
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}
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@Test
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public void isolationLevelAndReadLockModeSetAtClientAndTxnLevelTest() {
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SpannerOptions options =
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env.getTestHelper().getOptions().toBuilder()
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.setDefaultTransactionOptions(
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DefaultReadWriteTransactionOptions.newBuilder()
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.setIsolationLevel(IsolationLevel.REPEATABLE_READ)
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.setReadLockMode(ReadLockMode.OPTIMISTIC)
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.build())
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.build();
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try (Spanner spanner = options.getService()) {
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DatabaseClient client = spanner.getDatabaseClient(db.getId());
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Long updatedRows =
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client
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.readWriteTransaction(
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Options.isolationLevel(IsolationLevel.SERIALIZABLE),
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Options.readLockMode(ReadLockMode.PESSIMISTIC))
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.run(
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transaction ->
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transaction.executeUpdate(
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Statement.of("INSERT INTO T (K, V) VALUES ('test1', 2)")));
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assertThat(updatedRows).isEqualTo(1L);
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}
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}
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@Test
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public void userExceptionPreventsCommit() {
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class UserException extends Exception {

‎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;
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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));
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String title = null;
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while (resultSet.next()) {
1583-
title = resultSet.getString("AlbumTitle");
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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_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(),
21602113
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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