Connector/J 3.0.3 Release Notes

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Release date: 25 Jan 2022

MariaDB Connector/J 3.0.3 is a Stable (GA) release.

New version 3.0 is a complete rewrite of the connector, with code simplification, reduced size (15%), more than 90% coverage tested, with performance gain.

Licence is still LGPL-2.1 or later with copyright to MariaDB Corporation AB only (2.x was a fork from Drizzle-JDBC - BSD licensed)

What’s new :

• Binary prepare statement improvement

• faster connection creation

• Support of new 10.6 metadata skip

• Pipelining PREPARE

Performance

Other than features, connector permit significant performance improvements : Here are real world TPCC benchmarks results, comparing connector version 2.7.4 and 3.0.3

Binary prepare statement improvement

When using option useServerPrepStmts, the connector uses BINARY protocol, meaning executing PREPARE + EXECUTE commands.

Pipelining

Queries issued from the application are sent one by one to the server, waiting on the results of the first query before sending the next. Communication with the server follows this synchronous request-response messaging pattern.

When using binary protocol, a PREPARE command is issued (if not in cache) before executing an EXECUTE command.

For MariaDB server 10.2+, the connector will send an optimistic PREPARE + EXECUTE, sending queries one after another. EXECUTE command will be executed only if the PREPARE command succeeds. This avoids some network latency reading PREPARE result before sending EXECUTE command.

Support of new 10.6 metadata skip

10.6 Server with permit to avoid resending metadata when they haven’t changed. This concerns SQL commands that return a resultset, when using option useServerPrepStmts.

Now, the server will send metadata only if they have changed (DDL change for example). This avoids useless information transiting on the network and parsing those metadata.

Connector internal JMH Benchmark results, selecting one row of a 100 int column table :

Avoiding additional command on connection creation

Connection creation by default won't execute additional command to set session environement. Depending on options, there might be a few commands, but driver avoid them to the maximum.

REDO failover transaction

After a failover occurs, reconnection will be automatically done according to high-availability configuration. Even if implementation is now smaller and clearer, the result will be the same.

After reconnection, the connector might still throw an exception if the state is unsure. Failover on replica are transparent. This is different when the failover occurs during the execution of a query on a master server.

A new option transactionReplay permit to replay transactions : Most of the time, queries occur in transactions so redo transaction implementation will solve most of the failover cases transparently. Option is disabled by default. When enabled, all queries in a transaction are cached until transaction resolution. If a failover occurs, the driver will recreate a new connection and replay cache. There is a few limitations: When the last command was a "commit" sent to the server, an exception will be thrown, the driver cannot know the current state. application must have idempotent queries only (queries can be "replayable") If the transaction is too big (cache size limit set with new option transactionReplaySize), the driver won’t cache the transaction anymore, so a failover during that specific transaction will result in throwing an exception.

Better java version support

Driver uses Multi-Release JARs (MRJAR), to simultaneously contain implementations for different versions of java. This permit still supports Java 8, but provides solutions for higher versions of java.

Connector now provides a java 9 full module-info JPMS descriptor

Java 11 socket extended option TCP_KEEPIDLE, TCP_KEEPCOUNT and TCP_KEEPINTERVAL are now configurable with tcpKeepIdle, tcpKeepCount, tcpKeepInterval options respectively. (These options don't have any effect if using a java version lower than 11).

Authentication plugin restriction

A new option restrictedAuth permits to restrict authentication plugins. Example connection string jdbc:mariadb:*localhost/db?restrictedAuth=mysql_native_password,client_ed25519 will restrict plugin use of standard mysql_native_password and client_ed25519 only.*

Metadata queries performance improvement

Metadata queries use of information_schema improvement for partial or exact matching, permitting faster results.

Easy logging

Logging can now be easily enabled at runtime, using slf4j if present, or fallback to JDK logger / console if not.

• INFO level log connection error

• DEBUG/FINE level log commands

• TRACE/FINEST level log network exchanges

jdbc:mariadb scheme

It occurs that mysql AND mariadb driver are sometimes available in the same classpath, so, now, driver only accept jdbc:mariadb: by default.

If for some reason, connection string is required to be jdbc:mysql: Driver will be used only if connection string contain 'permitMysqlScheme'. example :jdbc:mysql:*localhost/test?permitMysqlScheme.*

Option changed

Ssl configuration use now a new option sslMode to simplify configuration Possible value are :

This can still be done by 2.x options (useSsl, disableSslHostnameVerification, trustServerCertificate) for compatibility, but this is the preferred way.

A new option timezone permits to force session timezone in case of client having a different timezone compare to server. if set timezone must to either offset or IANA tz (like '+5:00' or 'America/New_York')': connector will set connection timezone. This replace options useLegacyDatetimeCode and serverTimezone that did cause some problems when using .

Option removal

Even if connectors aim to be compatible with the 2.x version, there has been very few option removal since connection exists. This is now the time :

Specific support for aurora has been removed, since Issues were piling up without the community proposing any PR for them and without access for us to test those modifications.

Changelog

For a complete list of changes made in MariaDB Connector/J 3.0.3, with links to detailed information on each push, see the .