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docs: Add snippet for Repeatable Read configuration at client and transaction #3908

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Jun 25, 2025
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Original file line number Diff line number Diff line change
Expand Up @@ -32,13 +32,15 @@
import com.google.cloud.spanner.KeyRange;
import com.google.cloud.spanner.KeySet;
import com.google.cloud.spanner.Mutation;
import com.google.cloud.spanner.Options;
import com.google.cloud.spanner.ReadOnlyTransaction;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerBatchUpdateException;
import com.google.cloud.spanner.SpannerException;
import com.google.cloud.spanner.SpannerExceptionFactory;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.SpannerOptions.Builder.DefaultReadWriteTransactionOptions;
import com.google.cloud.spanner.Statement;
import com.google.cloud.spanner.Struct;
import com.google.cloud.spanner.TimestampBound;
Expand Down Expand Up @@ -71,6 +73,7 @@
import com.google.spanner.admin.database.v1.RestoreDatabaseRequest;
import com.google.spanner.admin.database.v1.RestoreInfo;
import com.google.spanner.v1.ExecuteSqlRequest.QueryOptions;
import com.google.spanner.v1.TransactionOptions.IsolationLevel;
import java.math.BigDecimal;
import java.time.Instant;
import java.time.ZoneId;
Expand Down Expand Up @@ -1552,6 +1555,47 @@ static void queryWithQueryOptions(DatabaseClient dbClient) {
}
// [END spanner_query_with_query_options]

// [START spanner_isolation_level_settings]
static void isolationLevelSetting(DatabaseId db) {
// The isolation level specified at the client-level will be applied to all
// RW transactions.
DefaultReadWriteTransactionOptions transactionOptions =
DefaultReadWriteTransactionOptions.newBuilder()
.setIsolationLevel(IsolationLevel.SERIALIZABLE)
.build();
SpannerOptions options =
SpannerOptions.newBuilder()
.setDefaultTransactionOptions(transactionOptions)
.build();
Spanner spanner = options.getService();
DatabaseClient dbClient = spanner.getDatabaseClient(db);
dbClient
// The isolation level specified at the transaction-level takes precedence
// over the isolation level configured at the client-level.
.readWriteTransaction(Options.isolationLevel(IsolationLevel.REPEATABLE_READ))
.run(transaction -> {
// Read an AlbumTitle.
String selectSql =
"SELECT AlbumTitle from Albums WHERE SingerId = 1 and AlbumId = 1";
ResultSet resultSet = transaction.executeQuery(Statement.of(selectSql));
String title = null;
while (resultSet.next()) {
title = resultSet.getString("AlbumTitle");
}
System.out.printf("Current album title: %s\n", title);

// Update the title.
String updateSql =
"UPDATE Albums "
+ "SET AlbumTitle = 'New Album Title' "
+ "WHERE SingerId = 1 and AlbumId = 1";
long rowCount = transaction.executeUpdate(Statement.of(updateSql));
System.out.printf("%d record updated.\n", rowCount);
return null;
});
}
// [END spanner_isolation_level_settings]

// [START spanner_create_backup]
static void createBackup(DatabaseAdminClient dbAdminClient, String projectId, String instanceId,
String databaseId, String backupId, Timestamp versionTime) {
Expand Down Expand Up @@ -2108,6 +2152,9 @@ static void run(
case "querywithqueryoptions":
queryWithQueryOptions(dbClient);
break;
case "isolationlevelsettings":
isolationLevelSetting(database);
break;
case "createbackup":
createBackup(dbAdminClient, database.getInstanceId().getProject(),
database.getInstanceId().getInstance(), database.getDatabase(),
Expand Down Expand Up @@ -2218,6 +2265,7 @@ static void printUsageAndExit() {
System.err.println(" SpannerExample querywithtimestampparameter my-instance example-db");
System.err.println(" SpannerExample clientwithqueryoptions my-instance example-db");
System.err.println(" SpannerExample querywithqueryoptions my-instance example-db");
System.err.println(" SpannerExample isolationlevelsettings my-instance example-db");
System.err.println(" SpannerExample createbackup my-instance example-db");
System.err.println(" SpannerExample listbackups my-instance example-db");
System.err.println(" SpannerExample listbackupoperations my-instance example-db backup-id");
Expand Down