Connector/J's load-balancing functionality only allowed the following events to trigger failover:

This meant that connections where auto-commit was enabled were not balanced, except for Exceptions, and this was problematic in the case of distribution of read-only work across slaves in a replication deployment.

The ability to load-balance while auto-commit is enabled has now been added to Connector/J. This introduces two new properties:

Load-balancing will be done after the statement is executed, before control is returned to the application. If rebalancing fails, the driver will silently swallow the resulting Exception (as the statement itself completed successfully). (Bug#55723)

Connector/J mapped both 3-byte and 4-byte UTF8 encodings to the same Java UTF8 encoding.

To use 3-byte UTF8 with Connector/J set characterEncoding=utf8 and set useUnicode=true in the connection string.

To use 4-byte UTF8 with Connector/J configure the MySQL server with character_set_server=utf8mb4. Connector/J will then use that setting as long as characterEncoding has not been set in the connection string. This is equivalent to autodetection of the character set. (Bug#58232)

The CallableStatementRegression test suite failed with a Null Pointer Exception because the OUT parameter in the I__S.PARAMETERS table had no name, that is COLUMN_NAME had the value NULL. (Bug#58232)

DatabaseMetaData.supportsMultipleResultSets() was hard-coded to return false, even though Connector/J supports multiple result sets. (Bug#57380)

Using the useOldUTF8Behavior parameter failed to set the connection character set to latin1 as required.

In versions prior to 5.1.3, the handshake was done using latin1, and while there was logic in place to explicitly set the character set after the handshake was complete, this was bypassed when useOldUTF8Behavior was true. This was not a problem until 5.1.3, when the handshake was modified to use utf8, but the logic continued to allow the character set configured during that handshake process to be retained for later use. As a result, useOldUTF8Behavior effectively failed. (Bug#57262)

Invoking a stored procedure containing output parameters by its full name, where the procedure was located in another database, generated the following exception:

Parameter index of 1 is out of range (1, 0)

(Bug#57022)

When a JDBC client disconnected from a remote server using Connection.close(), the TCP connection remained in the TIME_WAIT state on the server side, rather than on the client side. (Bug#56979)

Leaving Trust/ClientCertStoreType properties unset caused an exception to be thrown when connecting with useSSL=true, as no default was used. (Bug#56955)

When load-balanced connections swap servers, certain session state was copied from the previously active connection to the newly-selected connection. State synchronized included:

However, the read-only state was not synchronized, which caused problems if a write was attempted on a read-only connection. (Bug#56706)

When using Connector/J configured for failover (jdbc:mysql://host1,host2,... URLs), the non-primary servers re-balanced when the transactions on the master were committed or rolled-back. (Bug#56429)

An unhandled Null Pointer Exception (NPE) was generated in DatabaseMetaData.java when calling an incorrectly cased function name where no permission to access mysql.proc was available.

In addition to catching potential NPEs, a guard against calling JDBC functions with db_name.proc_name notation was also added. (Bug#56305)

Attempting to use JDBC4 functions on Connection objects resulted in errors being generated:

Exception in thread "main" java.lang.AbstractMethodError:
com.mysql.jdbc.LoadBalancedMySQLConnection.createBlob()Ljava/sql/Blob;
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at
com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:476)
   at $Proxy0.createBlob(Unknown Source)

(Bug#56099)