Changes in MySQL Connector/J 8.0.24 (2021-04-20, General Availability)

Version 8.0.24 is the latest General Availability release of the 8.0 series of MySQL Connector/J. It is suitable for use with MySQL Server versions 8.0, 5.7, and 5.6. It supports the Java Database Connectivity (JDBC) 4.2 API, and implements the X DevAPI.

• Functionality Added or Changed

• Bugs Fixed

Functionality Added or Changed

• X DevAPI: For X Protocol connections, the Server now provides three new kinds of notifications for disconnections:

  • Server shutdown: This is due to a server shutdown. It causes Connector/J to terminate all active and idle sessions connected to the server in the connection pool with the error message "Server shutdown in progress".

  • Connection idle: This is due to the connection idling for longer than the relevant timeout settings. It causes Connector/J to close the current connection with the error message "IO Read error: read_timeout exceeded".

  • Connection killed: This is due to the connection being killed by another client session. It causes Connector/J to close the connection in the current session with the error message “Session was killed".

  (WL #14202)

• A new connection property, scrollTolerantForwardOnly, has been introduced, which preserved the legacy behavior of Connector/J 8.0.17 and earlier by tolerating backward and absolute cursor movements on result sets of type ResultSet.TYPE_FORWARD_ONLY. This is for maintaining compatibility with legacy code that took advantage of the old behavior. See the description for scrollTolerantForwardOnly for details. (Bug #31747910)

  References: See also: Bug #30474158.

• Connector/J now supports "userless" authentication for JDBC connections: When the user for the connection is unspecified, Connector/J uses the name of the OS user who runs the application for authentication with the MySQL server. See Connector/J: Obtaining a connection from the DriverManager for more details. (WL #14453)

• Starting from this release, whenever an authentication plugin is explicitly set for the connection property defaultAuthenticationPlugin, the specified plugin takes precedence over the server's default when Connector/J negotiates a plugin with the server. There is no behavioral change for Connector/J if no value is explicitly set for the property, in which case the server's choice of default plugin takes precedence over the implicit default of mysql_native_password for Connector/J. See the description of defaultAuthenticationPlugin for details. (WL #14453)

• In the past, for JDBC connections, when the server closed a session because a client was idling beyond the period specified by the server's wait_timeout system variable, Connector/J returned a generic IO error. Connector/J now relays a clearer error message from the server. (WL #14392)

Bugs Fixed

• X DevAPI: Concurrently getting and closing multiple sessions from the same X DevAPI Client object might result in a ConcurrentModificationException thrown by Connector/J at the closing of a session. (Bug #31699993)

• X DevAPI: Under some specific conditions, when using Deflate as the algorithm for compression of X Protocol connections, Connector/J threw an AssertionFailedException (ASSERTION FAILED: Unknown message type: 57). It was because when a compressed packet was just a few bytes longer than the size of some internal buffer used by a Java InflaterInputStream, the leftover bytes from the inflate procedure were being discarded by Connector/J, causing inflation of subsequent packets to fail. With this fix, no data bytes are discarded, and the inflation works as expected. (Bug #31510398, Bug #99708)

• When a SecurityManager was in place, connections to a MySQL Server could not be established unless the client had been properly configured to use SASL-based LDAP authentication. It was because the AuthenticationLdapSaslClientPlugin in Connector/J requires a special permission to load the provider MySQLScramShaSasl when a SecurityManager is in place; but since the provider was loaded by a static initializer during initialization for the plugin, the lack of the permission was causing an error and then failures for all connections, even if the plugin was never used or enabled. This fix changes how the provider is loaded: the loading now happens only at the plugin instance's initialization and the initialization was deferred to the time when the plugin is actually needed, so that connections that do not use SASL-based LDAP authentication are unaffected by security settings regarding the plugin. (Bug #32526663, Bug #102188)

• When using Connector/J 8.0.23, ResultSetMetaData.getColumnClassName() did not return the correct class name corresponding to DATETIME columns. (Bug #32405590, Bug #102321)

• Creation of an UpdatableResultSet failed with a NullPointerException when it was generated by querying a view with a derived value. (Bug #32338451, Bug #102131)

• Using getLong() on the CHAR_OCTET_LENGTH column of the ResultSet for DatabaseMetaData.getProcedureColumns() (or getFunctionColumns()) resulted in a NumberOutOfRange exception when the column's value exceeded 2³² − 1. With this patch, the value of 2³² − 1 is returned in the situation. (Bug #32329915, Bug #102076)

• Connections to a server could not be established when the user supplied an implementation of the ConnectionPropertiesTransform interface using the connection property propertiesTransform. This was because Connector/J called PropertyKey.PORT.getKeyName() instead of PropertyKey.HOST.getKeyName() for getting the host name, and that has been corrected by this fix. (Bug #32151143, Bug #101596)

• A NullPointerException was returned when a statement that could not be used as a ServerPreparedStatement was executed and the connection property useUsageAdvisor was set to true. With this fix, a SQLException is returned instead. (Bug #32141210, Bug #101558)

• Using the setSessionMaxRows() method on a closed connection resulted in a NullPointerException. With this fix, a SQLNonTransientConnectionException is thrown instead, with the error message "No operations allowed after connection closed." (Bug #22508715)

• Using the setObject() method for a target type of Types.TIME resulted in a SQLException when the value to be set had a fractional part, or when the value did not fit any pattern described in Date and Time Literals. This patch introduced a new logic that can handle fractional parts; also, it performs the conversion according to the patterns of the literals and, when needed, the target data type. (Bug #20391832)