MySQL Connector/J Release Notes  /  Changes in MySQL Connector/J 5.0  /  Changes in MySQL Connector/J 5.0.6 (2007-05-15)

Changes in MySQL Connector/J 5.0.6 (2007-05-15)

Functionality Added or Changed

  • random: The driver will pick a random host for each request. This tends to work better than round-robin, as the randomness will somewhat account for spreading loads where requests vary in response time, while round-robin can sometimes lead to overloaded nodes if there are variations in response times across the workload.

  • com.mysql.jdbc.[NonRegistering]Driver now understands URLs of the format jdbc:mysql:replication:// and jdbc:mysql:loadbalance:// which will create a ReplicationConnection (exactly like when using [NonRegistering]ReplicationDriver) and an experimental load-balanced connection designed for use with SQL nodes in a MySQL Cluster/NDB environment, respectively.

    In an effort to simplify things, we're working on deprecating multiple drivers, and instead specifying different core behavior based upon JDBC URL prefixes, so watch for [NonRegistering]ReplicationDriver to eventually disappear, to be replaced with com.mysql.jdbc[NonRegistering]Driver with the new URL prefix.

  • More intelligent initial packet sizes for the "shared" packets are used (512 bytes, rather than 16K), and initial packets used during handshake are now sized appropriately as to not require reallocation.

  • Fixed issue where a failed-over connection would let an application call setReadOnly(false), when that call should be ignored until the connection is reconnected to a writable master unless failoverReadOnly had been set to false.

  • bestResponseTime: The driver will route the request to the host that had the best response time for the previous transaction.

  • Added an experimental load-balanced connection designed for use with SQL nodes in a MySQL Cluster/NDB environment (This is not for master-slave replication. For that, we suggest you look at ReplicationConnection or lbpool).

    If the JDBC URL starts with jdbc:mysql:loadbalance://host-1,host-2,...host-n, the driver will create an implementation of java.sql.Connection that load balances requests across a series of MySQL JDBC connections to the given hosts, where the balancing takes place after transaction commit.

    Therefore, for this to work (at all), you must use transactions, even if only reading data.

    Physical connections to the given hosts will not be created until needed.

    The driver will invalidate connections that it detects have had communication errors when processing a request. A new connection to the problematic host will be attempted the next time it is selected by the load balancing algorithm.

    There are two choices for load balancing algorithms, which may be specified by the loadBalanceStrategy JDBC URL configuration property:

    • random: The driver will pick a random host for each request. This tends to work better than round-robin, as the randomness will somewhat account for spreading loads where requests vary in response time, while round-robin can sometimes lead to overloaded nodes if there are variations in response times across the workload.

    • bestResponseTime: The driver will route the request to the host that had the best response time for the previous transaction.

  • When useLocalSessionState is set to true and connected to a MySQL-5.0 or later server, the JDBC driver will now determine whether an actual commit or rollback statement needs to be sent to the database when Connection.commit() or Connection.rollback() is called.

    This is especially helpful for high-load situations with connection pools that always call Connection.rollback() on connection check-in/check-out because it avoids a round-trip to the server.

  • Driver will now use INSERT INTO ... VALUES (DEFAULT)form of statement for updatable result sets for ResultSet.insertRow(), rather than pre-populating the insert row with values from DatabaseMetaData.getColumns()(which results in a SHOW FULL COLUMNS on the server for every result set). If an application requires access to the default values before insertRow() has been called, the JDBC URL should be configured with populateInsertRowWithDefaultValues set to true.

    This fix specifically targets performance issues with ColdFusion and the fact that it seems to ask for updatable result sets no matter what the application does with them.

  • Give better error message when "streaming" result sets, and the connection gets clobbered because of exceeding net_write_timeout on the server.

  • New configuration property, enableQueryTimeouts (default true).

    When enabled, query timeouts set with Statement.setQueryTimeout() use a shared java.util.Timer instance for scheduling. Even if the timeout doesn't expire before the query is processed, there will be memory used by the TimerTask for the given timeout which won't be reclaimed until the time the timeout would have expired if it hadn't been cancelled by the driver. High-load environments might want to consider disabling this functionality. (this configuration property is part of the maxPerformance configuration bundle).

  • Added configuration property useDynamicCharsetInfo. If set to false (the default), the driver will use a per-connection cache of character set information queried from the server when necessary, or when set to true, use a built-in static mapping that is more efficient, but isn't aware of custom character sets or character sets implemented after the release of the JDBC driver.

    Note

    This only affects the padCharsWithSpace configuration property and the ResultSetMetaData.getColumnDisplayWidth() method.

  • Added configuration property padCharsWithSpace (defaults to false). If set to true, and a result set column has the CHAR type and the value does not fill the amount of characters specified in the DDL for the column, the driver will pad the remaining characters with space (for ANSI compliance).

Bugs Fixed

  • More useful error messages are generated when the driver thinks a result set is not updatable. (Thanks to Ashley Martens for the patch). (Bug #28085)

  • Connection.getTransactionIsolation() uses "SHOW VARIABLES LIKE" which is very inefficient on MySQL-5.0+ servers. (Bug #27655)

  • Fixed issue where calling getGeneratedKeys() on a prepared statement after calling execute() didn't always return the generated keys (executeUpdate() worked fine however). (Bug #27655)

  • CALL /* ... */ some_proc() doesn't work. As a side effect of this fix, you can now use /* */ and # comments when preparing statements using client-side prepared statement emulation.

    If the comments happen to contain parameter markers (?), they will be treated as belonging to the comment (that is, not recognized) rather than being a parameter of the statement.

    Note

    The statement when sent to the server will contain the comments as-is, they're not stripped during the process of preparing the PreparedStatement or CallableStatement.

    (Bug #27400)

  • ResultSet.get*() with a column index < 1 returns misleading error message. (Bug #27317)

  • Using ResultSet.get*() with a column index less than 1 returns a misleading error message. (Bug #27317)

  • Comments in DDL of stored procedures/functions confuse procedure parser, and thus metadata about them can not be created, leading to inability to retrieve said metadata, or execute procedures that have certain comments in them. (Bug #26959)

  • Fast date/time parsing doesn't take into account 00:00:00 as a legal value. (Bug #26789)

  • PreparedStatement is not closed in BlobFromLocator.getBytes(). (Bug #26592)

  • When the configuration property useCursorFetch was set to true, sometimes server would return new, more exact metadata during the execution of the server-side prepared statement that enables this functionality, which the driver ignored (using the original metadata returned during prepare()), causing corrupt reading of data due to type mismatch when the actual rows were returned. (Bug #26173)

  • CallableStatements with OUT/INOUT parameters that are "binary" (BLOB, BIT, (VAR)BINARY, JAVA_OBJECT) have extra 7 bytes. (Bug #25715)

  • Whitespace surrounding storage/size specifiers in stored procedure parameters declaration causes NumberFormatException to be thrown when calling stored procedure on JDK-1.5 or newer, as the Number classes in JDK-1.5+ are whitespace intolerant. (Bug #25624)

  • Client options not sent correctly when using SSL, leading to stored procedures not being able to return results. Thanks to Don Cohen for the bug report, testcase and patch. (Bug #25545)

  • Statement.setMaxRows() is not effective on result sets materialized from cursors. (Bug #25517)

  • BIT(> 1) is returned as java.lang.String from ResultSet.getObject() rather than byte[]. (Bug #25328)