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What's new in this version:

# Bugs fixed:

* Incompatible Change: Replication: As of MySQL 5.5.6, handling of CREATE TABLE IF NOT EXISTS ... SELECT statements has been changed for the case that the destination table already exists:
- Previously, for CREATE TABLE IF NOT EXISTS ... SELECT, MySQL produced a warning that the table exists, but inserted the rows and wrote the statement to the binary log anyway. By contrast, CREATE TABLE ... SELECT (without IF NOT EXISTS) failed with an error, but MySQL inserted no rows and did not write the statement to the binary log.
- MySQL now handles both statements the same way when the destination table exists, in that neither statement inserts rows or is written to the binary log. The difference between them is that MySQL produces a warning when IF NOT EXISTS is present and an error when it is not.
- This change in handling of IF NOT EXISTS results in an incompatibility for statement-based replication from a MySQL 5.1 master with the original behavior and a MySQL 5.5 slave with the new behavior. Suppose that CREATE TABLE IF NOT EXISTS ... SELECT is executed on the master and the destination table exists. The result is that rows are inserted on the master but not on the slave. (Row-based replication does not have this problem.)
- To address this issue, statement-based binary logging for CREATE TABLE IF NOT EXISTS ... SELECT is changed in MySQL 5.1 as of 5.1.51:
- If the destination table does not exist, there is no change: The statement is logged as is.
- If the destination table does exist, the statement is logged as the equivalent pair of CREATE TABLE IF NOT EXISTS and INSERT ... SELECT statements. (If the SELECT in the original statement is preceded by IGNORE or REPLACE, the INSERT becomes INSERT IGNORE or REPLACE, respectively.)
- This change provides forward compatibility for statement-based replication from MySQL 5.1 to 5.5 because when the destination table exists, the rows will be inserted on both the master and slave. To take advantage of this compatibility measure, the 5.1 server must be at least 5.1.51 and the 5.5 server must be at least 5.5.6.To upgrade an existing 5.1-to-5.5 replication scenario, upgrade the master first to 5.1.51 or higher. Note that this differs from the usual replication upgrade advice of upgrading the slave first.A workaround for applications that wish to achieve the original effect (rows inserted regardless of whether the destination table exists) is to use CREATE TABLE IF NOT EXISTS and INSERT ... SELECT statements rather than CREATE TABLE IF NOT EXISTS ... SELECT statements.Along with the change just described, the following related change was made: Previously, if an existing view was named as the destination table for CREATE TABLE IF NOT EXISTS ... SELECT, rows were inserted into the underlying base table and the statement was written to the binary log. As of MySQL 5.1.51 and 5.5.6, nothing is inserted or logged. (Bug#47442, Bug#47132, Bug#48814, Bug#49494)
* Incompatible Change: Previously, if you flushed the logs using FLUSH LOGS or mysqladmin flush-logs and mysqld was writing the error log to a file (for example, if it was started with the --log-error option), it renamed the current log file with the suffix -old, then created a new empty log file. This had the problem that a second log-flushing operation thus caused the original error log file to be lost unless you saved it under a different name. For example, you could use the following commands to save the file: shell> mysqladmin flush-logs shell> mv host_name.err-old backup-directory To avoid the preceding file-loss problem, renaming no longer occurs. The server merely closes and reopens the log file. To rename the file, you can do so manually before flushing. Then flushing the logs reopens a new file with the original file name. For example, you can rename the file and create a new one using the following commands: shell> mv host_name.err host_name.err-old shell> mysqladmin flush-logs shell> mv host_name.err-old backup-directory (Bug#29751)
* Partitioning: When the storage engine used to create a partitioned table was disabled, attempting to drop the table caused the server to crash. (Bug#46086)
* If a view was named as the destination table for CREATE TABLE ... SELECT, the server produced a warning whether or not IF NOT EXISTS was used. Now it produces a warning only when IF NOT EXISTS is used, and an error otherwise. (Bug#55777)
* The CHECK TABLE command could cause a time-consuming verification of the InnoDB adaptive hash index memory structure. Now this extra checking is only performed in binaries built for debugging. (Bug#55716)
* After the fix for Bug#39653, the shortest available secondary index was used for full table scans. The primary clustered key was used only if no secondary index could be used. However, when the chosen secondary index includes all columns of the table being scanned, it is better to use the primary index because the amount of data to scan is the same but the primary index is clustered. This is now taken into account. (Bug#55656)
* (Bug#55627)
* The server was not checking for errors generated during the execution of Item::val_xxx() methods when copying data to a group, order, or distinct temp table's row. (Bug#55580)
* ORDER BY clauses that included user variable expressions could cause a debug assertion to be raised. (Bug#55565)
* Queries involving predicates of the form const NOT BETWEEN not_indexed_column AND indexed_column could return incorrect data due to incorrect handling by the range optimizer. (Bug#54802)
* MIN() or MAX() with a subquery argument could raise a debug assertion for debug builds or return incorrect data for nondebug builds. (Bug#54465)
* INFORMATION_SCHEMA plugins with no deinit() method resulted in a memory leak. (Bug#54253)
* INSERT IGNORE INTO ... SELECT statements could cause a debug assertion to be raised. (Bug#54106)
* The fix for Bug#30234 caused the server to reject the DELETE tbl_name.* ... Access compatibility syntax for multiple-table DELETE statements. (Bug#53034)
* Enumeration plugin variables were subject to a type casting error, causing inconsistent results between different platforms. (Bug#42144)
* A PKG install on Solaris put some files in incorrect locations. (Bug#31058)