使用 spring R2DBC 连接 mySQL 服务器版本 8 时出现未知的系统变量“tx_isolation”

Question

I created a new spring boot project using the IntelliJ Idea's spring initializer and checked the Web/Spring reactive Web and the SQL/Spring data R2DBC dependencies.

I also added the the dependency to the R2DBC implementation for MySQL

        <dependency>
            <groupId>dev.miku</groupId>
            <artifactId>r2dbc-mysql</artifactId>
            <version>0.8.2.RELEASE</version>
        </dependency>

and the java connector

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

Asking the version of the MySQL server from a console with select version(); I get 8.0.17

The connection factory configuration is like this:

@Configuration
@RequiredArgsConstructor
public class R2dbcConfig extends AbstractR2dbcConfiguration {

    @Bean
    public ConnectionFactory connectionFactory() {
        ConnectionFactoryOptions conf = ConnectionFactoryOptions.builder()
                .option(DRIVER, "mysql")
                .option(HOST, "the.db.url")
                .option(PORT, 33066612)
                .option(USER, "myUserName")
                .option(PASSWORD, "myPassword")
                .option(DATABASE, "aDbName")
                .build();
        return ConnectionFactories.find(conf);
    }
}

Nevertheless, when I run the application I get the following exception

reactor.core.Exceptions$ErrorCallbackNotImplemented: org.springframework.dao.DataAccessResourceFailureException: Failed to obtain R2DBC Connection; nested exception is io.r2dbc.spi.R2dbcNonTransientResourceException: [1193] Unknown system variable 'tx_isolation'
Caused by: org.springframework.dao.DataAccessResourceFailureException: Failed to obtain R2DBC Connection; nested exception is io.r2dbc.spi.R2dbcNonTransientResourceException: [1193] Unknown system variable 'tx_isolation'

Answers to similar questions instructed the asker to update the version of the mysql:mysql-connector-java to 8.+ , and according to IntelliJ the versión resolved by maven is 8.0.26 . Curiously, if I remove the connector dependency the result is exactly the same.

So, I debbuged the R2DBC implementation to find out what is happening and I discovered that during the handshake, the dev.miku.r2dbc.mysq.QueryFlow#initHandshake method receives a HandshakeRequest message whose headers tell that the server version is "5.5.30". And that causes the R2DBC implementation to use the old "tx_isolation" system variable name instead of the new "transaction_isolation".

Why? What am I missing?

Answer 1

https://dev.mysql.com/doc/refman/8.0/en/mysql-nutshell.html says:

The tx_isolation and tx_read_only system variables have been removed. Use transaction_isolation and transaction_read_only instead.

You checked and discovered the server version is 8.0.17. This is more authoritative than the handshake headers message.

I recommend searching your classpath for any leftover jar files with old versions of the connector. You may have both version 8.0.26 of the connector and an older version that hasn't been updated to use the new option names.

Answer 2

Could you solved it? I found that R2dbc mysql driver doesn't get my MySql version, because it has a check of it to ask for tx_isolation or transaction_isolation.

The solution I got was changing the driver to Jasync.

//DB
implementation("com.github.jasync-sql:jasync-r2dbc-mysql:2.0.4")
implementation("io.r2dbc:r2dbc-h2")
implementation("org.springframework.boot:spring-boot-starter-data-r2dbc:2.6.0")

And my config:

@Configuration
@EnableTransactionManagement
@EnableConfigurationProperties(DbPropertiesConfig::class)
class DataSourceConfiguration {
@Configuration
    class ProdMySQLConfiguration(@Autowired val dbPropertiesConfig: DbPropertiesConfig) : AbstractR2dbcConfiguration() {

        @Bean
        @Throws(FuryDecryptException::class, FuryUpdateException::class, FuryNotFoundAPPException::class)
        override fun connectionFactory(): ConnectionFactory =
                JasyncConnectionFactory(MySQLConnectionFactory(
                        com.github.jasync.sql.db.Configuration(
                                database = dbPropertiesConfig.db,
                                port = dbPropertiesConfig.port,
                                username = dbPropertiesConfig.username,
                                host = dbPropertiesConfig.host,
                                password = dbPropertiesConfig.password
                        )
                ))
    }

}

Taking into consideration I have that DbPropertiesConfig in my yml.

Doc/Example: Doc Example

Gitter: https://gitter.im/jasync-sql/support