This is a milestone release, for use at your own risk. Significant development changes take place in milestone releases and you may encounter compatibility issues, such as data format changes that require attention in addition to the usual procedure of running mysql_upgrade. For example, you may find it necessary to dump your data with mysqldump before the upgrade and reload it afterward.
Functionality Added or Changed
Important Change; Replication:
SHOW SLAVE STATUS when run
STOP SLAVE can
take a long time to execute if the slave SQL thread was in the
midst of applying a large update. To fix this problem, a new
NONBLOCKING option has been added to the
SHOW SLAVE STATUS statement. When
this option is used,
SHOW SLAVE STATUS does
not wait on the SQL or I/O threads but returns immediately. This
means that the reported states of these threads may not be
completely up to date when the option is used.
NONBLOCKING is intended primarily for use by
monitoring tools in which obtaining an immediate response is
more important than having the most timely data.
(Bug #15993588, Bug #67879)
Important Change; Replication:
option for mysqlbinlog, which causes the
MySQL Server to employ idempotent mode. This causes suppression
of all duplicate-key and key-not-found errors when processing
updates from the binary log. The mode is in effect for the
current mysqlbinlog client and client session
is no longer supported. The server recognizes but ignores the
DELAYED keyword, handles the insert as a
nondelayed insert, and generates an
warning. (“INSERT DELAYED is no longer supported. The
statement was converted to INSERT.”). Similarly,
DELAYED is handled as a nondelayed replace. The
DELAYED keyword will be removed in a future
In addition, several
or features were removed:
--delayed-insert option for
MAX_TIMER_WRITE_DELAYED columns of the
If you upgrade to this release of MySQL from an earlier
version, you must run mysql_upgrade (and
restart the server) to incorporate these changes into the
mysqlbinlog no longer writes comments
Windows Vista, Windows Server 2008, and newer support native
symlinking using the mklink command. This
makes the MySQL Server implementation of database symbolic links
.sym files redundant, so that
mechanism is now removed. This change has the following
The server now issues a warning if an index is created that duplicates an existing index, or an error in strict SQL mode. (Bug #37520, Bug #11748842)
Previously, Control+C in mysql interrupted the current statement if there was one, or exited mysql if not. Now Control+C interrupts the current statement if there was one, or cancels any partial input line otherwise, but does not exit. (Bug #66583, Bug #14554568)
client-side authentication plugin is intended for authentication
schemes that require the server to receive the password as
entered on the client side, without hashing. Because the
password is sent in the clear, this plugin should be used within
the context of a secure connection, such as an SSL connection,
to avoid exposing the password over the network. To make
inadvertent use of this plugin less likely, it is now required
that clients explicitly enable it. This can be done several
environment variable to a value that begins with
y. This enables the plugin for all client
The mysql, mysqladmin,
and mysqlslap client programs support an
--enable-cleartext-plugin option that
enables the plugin on a per-invocation basis.
mysql_options() C API
function supports a
MYSQL_ENABLE_CLEARTEXT_PLUGIN option that
enables the plugin on a per-connection basis. Also, any
program that uses
reads option files can enable the plugin by including an
enable-cleartext-plugin option in an
option group read by the client library.
MySQL now supports stacked diagnostics areas. When a push to the
diagnostics area stack occurs, the first (current) diagnostics
area becomes the second (stacked) diagnostics area and a new
current diagnostics area is created as a copy of it. Within a
condition handler, executed statements modify the new current
diagnostics area, but
DIAGNOSTICS can be used to inspect the stacked
diagnostics area to obtain information about the condition that
caused the handler to activate, independent of current
conditions within the handler itself. (Previously, there was a
single diagnostics area. To inspect handler-activating
conditions within a handler, it was necessary to check this
diagnostics area before executing any statements that could
change it.) See
GET DIAGNOSTICS Syntax, and
The MySQL Diagnostics Area.
UpdateXML() functions supported a
maximum length of 127 characters for XPath expressions supplied
to them as arguments. This limitation has now been removed.
(Bug #13007062, Bug #62429)
InnoDB: During an online DDL operation, a duplicate key error could be incorrectly issued if a record was inserted and subsequently updated while the table was being rebuilt. (Bug #14723456)
Creating and altering tables repeatedly would result in a memory
leak that was due to a duplicate key error. The duplicate key
error occurred because the
row_merge_build_indexes function did not call
row_fts_psort_info_destroy often enough. As
full-text search indexes were created with a unique index, the
unique index would fail due to the duplicate key error, and
full-text search build resource would not be released.
If the server crashed at a precise moment during an
ALTER TABLE operation that
rebuilt the clustered
index for an
InnoDB table, the
original table could be inaccessible afterward. An example of
such an operation is
ALTER TABLE ... ADD PRIMARY
KEY The fix preserves the original table if the server
halts during this operation. You might still need to rename the
.ibd file manually to restore the original
table contents: in MySQL 5.6 and higher, rename from
within the database directory; prior to MySQL 5.6, the temporary
file to rename is
InnoDB IO threads within Performance Schema were exposed with
the following name:
io_handler_thread”. This fix
implements specific keys such as
io_ibuf_handler_thread to differentiate
InnoDB IO threads within Performance Schema.
Inserting data of varying record lengths into an
InnoDB table that used
compression could cause
the server to halt with an error.
(Bug #14554000, Bug #13523839, Bug #63815, Bug #12845774, Bug #61456, Bug #12595091, Bug #61208)
InnoDB: This fix addresses an assert condition that would occur when inserting large BLOBs into tablespaces with a 4KB physical page size or into some compressed tables. Extents would not be allocated soon enough for tablespaces with smaller physical page sizes. (Bug #14520559)
InnoDB: If a table was defined with an index key length very close to the upper length limit of 3072, a query against that table could cause a serious error. (Bug #14500557, Bug #14537695)
In debug builds, a mismatch in the
PAGE_FREE list would cause an assertion.
InnoDB: On Linux systems, certain I/O requests that read or wrote fewer than the requested number of bytes could cause the server to crash. This issue could happen more frequently with asynchronous I/O requests. The messages did not clearly identify what type of error occurred:
InnoDB: Operating system error number 0 in a file operation. InnoDB: Error number 0 means 'Success'.
With this fix, MySQL retries the operation several times before
giving up. (The number of retries is defined by the constant
NUM_RETRIES_ON_PARTIAL_IO in the source code,
default value 10.)
(Bug #11761646, Bug #54160)
When the server is started with
--skip-partition, it should reject DDL or DML
statements on partitioned tables. However, for
DROP TABLE, the server dropped
.frm file, and for
RENAME TABLE, the server renamed
mysqlbinlog did not properly decode
DECIMAL values in a row-based
binary log. This could cause invalid values to be printed out
References: See also Bug #17544169.
When using mysqlbinlog with the
--verbose option to read a
binary log written by a MySQL server using row-based or
mixed-format logging, invalid SQL could be produced when
comments appeared inside
statements. One way in which this could happen was when a
function that updated data was used within an
mysql_upgrade on the master broke replication
when the slave was run with
--log-output equal to
STOP SLAVE caused a
spurious Error reading packet from server: Lost
connection to MySQL server during query message to
be written to the error log.
(Bug #11761457, Bug #12977988, Bug #53955)
When an error occurs in the slave SQL thread, this causes the
Slave_SQL_Errno columns from
SHOW SLAVE STATUS to display the
reason for the error. The error number should be one of the
usual constants ER_* defined in
sql/share/errmsg.txt, and the error message
should be the corresponding string. However, in some cases,
Slave_SQL_Errno was set to something other
ER_* number, and
Slave_SQL_Error to a hard-coded error message
rather than a translatable string from
sql/share/errmsg.txt. Now all errors shown
SHOW SLAVE STATUS originate in
sql/share/errmsg.txt, as expected.
(Bug #11760365, Bug #52768)
Microsoft Windows: On Microsoft Windows, CMake entries for POSIX API's not found on Microsoft Windows were added to the CMake cache. This decreases the number of expected "Not found" errors while compiling MySQL. (Bug #14790333)
On Microsoft Windows, queries referring to a table with invalid
characters would search the system for invalid file names. The
generated system error code
ERROR_INVALID_NAME) was not recognized by
MySQL, so this unknown error would be reported to the server log
as "ERRNO: 22 - INVALID ARGUMENT". MySQL now recognizes these
errors and reports them as the table does not existing, and it
no longer logs them to the server error log.
On Windows, starting the server with
--console caused the server to
write to the log file but not the console. Before MySQL 5.5.3,
this occurred only if
was specified after
--log-error no matter the option
order so that
console output in all cases.
(Bug #14207773, Bug #65592)
It was possible to specify a
Pipe that was already in use. This is no longer allowed,
as an error is now emitted and the process is aborted. After
mysqld.exe was started in Named Pipe mode
with a pipe name that was already used by a different instance,
neither instance was able to shut down properly when a shutdown
command was received from a
TCP socket in any
of the processes. Therefore,
(Bug #13891058, Bug #61885)
On Microsoft Windows, a failed API or function call in
mysqld.exe could sometimes report the error
code 22, instead of the proper error code.
Transactions originating on a replication master are applied on
slaves as if using
transactions replayed from a binary log were not. Now
transactions being replayed from a log are handled in the same
way as those coming from a “live” replication
NdbOperation::AbortOption Type, for more
Joins of exactly 32 tables and containing a
HAVING clause returned an empty result.
The parser rejected some legal
thread_cache_size to a
negative value at server startup resulted in a value of 16384
rather than 0.
displayed nonprintable characters in the XID data. Now such
characters are hex encoded.
The return value from
IS_USED_LOCK() was reported using
the wrong data type.
There was no warning at startup if the server was started with
When resolving outer fields,
Item_field::fix_outer_fields() creates new
Item_refs for each execution of a prepared
statement, so these must be allocated in the runtime memroot.
The memroot switching before resolving
JOIN::having caused these to be allocated in
the statement root, leaking memory for each prepared statement
Activation of a stored program handler did not preserve the current diagnostics stack. (Bug #14342913)
In debug builds, killing a
statement caused an assertion to be raised.
If an error occurred during evaluation of the
BEFORE expression of a
LOGS BEFORE statement, the statement did not abort as
it should have and later raised an assertion.
For the index merge access method, the optimizer could make a suboptimal choice of indexes to use. (Bug #14095506)
An assertion could be raised if the attempt to open the
.frm file for a temporary table failed.
If the state of the Event Scheduler was changed during server shutdown, the server could crash. (Bug #13002460)
When storing the definition for a view that used the
LOWER() function, the function
call was replaced by
LCASE(), respectively (as shown
in the output of
VIEW). This was in spite of the fact that
LCASE() being MySQL synonyms for these. This
made it more difficult to move databases between MySQL and other
With this fix, calls to
LOWER() within views are no longer rewritten
when storing their definitions; instead,
UCASE() is now rewritten as
UPPER() in stored view definitions, and
increases the portability of the views.
For queries that accessed an
INFORMATION_SCHEMA table in a subquery, an
attempt to lock a mutex that had already been locked could cause
a server crash.
Range checked for each record
optimization is now used for conditions with outer query
INSERT INTO ...
SELECT statement that inserted no rows unnecessarily
invalidated statements in the query cache that used the target
(Bug #50065, Bug #11757947)
The server refused client connections while executing
(Bug #63178, Bug #13418619)
Concurrent inserts were blocked by selects if the inserts were generated from within a stored procedure. (Bug #58689, Bug #11765698)
Concurrent execution of
DATABASE and any of
EVENT could be written to the binary log in the wrong
order, causing replication failure.
(Bug #65428, Bug #14127220)
INSERT INTO ... SELECT
... ON DUPLICATE KEY UPDATE and
LOAD DATA CONCURRENT
REPLACE took too weak a lock, leading to the
possibility of concurrent
returning inconsistent results.
(Bug #38046, Bug #11749055)
read_only is enabled, it is still
permitted to create
TEMPORARY tables. But in
this case, a non-
TEMPORARY table with the
same name could also be created, which should not be permitted.
(Bug #64992, Bug #13969578)
An event was not dropped from the
table under these circumstances: The event was created while the
event scheduler was enabled; the scheduler was disabled and
re-enabled; the event expiration time was reached.
(Bug #34804, Bug #11748012)
ALTER TABLE to rename a
. resulted in a table with no name.
(Bug #49636, Bug #11757569)
SHOW CREATE VIEW failed if the
tables underlying the view were changed.
(Bug #61718, Bug #12762393)
STATUS caused performance problems on busy servers due
to lock contention.
(Bug #42930, Bug #11751904)
For a view defined on a
the server could create an invalid view definition.
(Bug #65388, Bug #14117018, Bug #72018, Bug #18405221)
For queries using
on string data types, the
access condition could be evaluated again as part of the query
condition or pushed down as an index condition to the storage
(Bug #66983, Bug #14682735)
ALTER TABLE statement that
renamed or changed the default value of a
BINARY column, the alteration was
done using a table copy and not in place.
(Bug #67141, Bug #14735373, Bug #69580, Bug #17024290)
A view was created with an incorrect definition if the
WHERE clause contained string literals and
set to different character sets.
(Bug #63094, Bug #13520710)