Dear MySQL users,

MySQL Server 5.6.20, a new version of the popular Open Source
Database Management System, has been released. MySQL 5.6.20 is
recommended for use on production systems.

For an overview of what's new in MySQL 5.6, please see

http://dev.mysql.com/doc/refman/5.6/en/mysql-nutshell.html

Starting with 5.6.11, Microsoft Windows packages for MySQL 5.6
are available both as a "full" installer and as a "web" installer.
The full installer is significantly larger and comes bundled with
the latest software releases available. This bundle makes it easy
to download and configure a full server and development suite.

The web installer doesn't come bundled with any actual products
and instead relies on download-on-demand to fetch only the
products you choose to install. This makes the initial download
much smaller but increases install time as the individual products
will need to be downloaded.

For information on installing MySQL 5.6.20 on new servers or upgrading
to MySQL 5.6.20 from previous MySQL releases, please see

http://dev.mysql.com/doc/refman/5.6/en/installing.html

MySQL Server is available in source and binary form for a number of
platforms from our download pages at

http://dev.mysql.com/downloads/

Not all mirror sites may be up to date at this point in time, so if you
can't find this version on some mirror, please try again later or choose
another download site.

We welcome and appreciate your feedback, bug reports, bug fixes,
patches, etc:

https://wikis.oracle.com/display/mysql/Contributing

The following section lists the changes in the MySQL source code since
the previous released version of MySQL 5.6. It may also be viewed
online at

http://dev.mysql.com/doc/relnotes/mysql/5.6/en/news-5-6-20.html

Enjoy!

Changes in MySQL 5.6.20 (2014-07-31)

Security Notes

* Security Fix: The linked OpenSSL library for the MySQL 5.6
Commercial Server has been updated from version 1.0.1g to
version 1.0.1h. Versions of OpenSSL prior to and including
1.0.1g are reported to be vulnerable to CVE-2014-0224
(http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0224).
This change does not affect the Oracle-produced MySQL
Community build of MySQL Server 5.6, which uses the yaSSL
library instead. (CVE-2014-0224)

InnoDB Notes

* Important Change: Redo log writes for large, externally stored
BLOB fields could overwrite the most recent checkpoint. The
5.6.20 patch limits the size of redo log BLOB writes to 10% of
the redo log file size. The 5.7.5 patch addresses the bug
without imposing a limitation. For MySQL 5.5, the bug remains
a known limitation.
As a result of the redo log BLOB write limit introduced for
MySQL 5.6, innodb_log_file_size should be set to a value
greater than 10 times the largest BLOB data size found in the
rows of your tables plus the length of other variable length
fields (VARCHAR, VARBINARY, and TEXT type fields). Failing to
do so could result in "Row size too large" errors. No action
is required if your innodb_log_file_size setting is already
sufficiently large or your tables contain no BLOB data. (Bug
#16963396, Bug #19030353, Bug #69477)

Functionality Added or Changed

* Replication: The new system variable binlog_impossible_mode
controls what happens if the server cannot write to the binary
log, for example, due to a file error. For backward
compatibility, the default for binlog_impossible_mode is
IGNORE_ERROR, meaning the server logs the error, halts
logging, and continues updates to the database. Setting this
variable to ABORT_SERVER makes the server halt logging and
shut down the server if it can not write to the binary log.
(Bug #51014, Bug #11758766)

* CMake support was updated to handle CMake version 3. (Bug
#19001781)

* New Debian7, Ubuntu12.04, and Ubuntu14.04 distribution support
that was introduced with 5.6.17 now comes with the
platform-specific packaging source placed under the packaging
directory, in the deb-precise, deb-wheezy, and deb-trusty
directories. (Bug #19020385)

* Support for LinuxThreads has been removed from the source
code. LinuxThreads was superseded by NPTL in Linux 2.6. (Bug
#17007529, Bug #72888, Bug #18913935)

* By default, mysql_install_db creates a my.cnf file in the
installation base directory using a template. This may be
undesireable for some deployments. To enable this behavior to
be suppressed, mysql_install_db now supports a --keep-my-cnf
option to preserve any existing my.cnf file and not create a
new my.cnf file. (Bug #71600, Bug #18205019)

* The mysqlhotcopy utility is now deprecated and will be removed
in a future version of MySQL. Among the reasons for this: It
works only for the MyISAM and ARCHIVE storage engines; it
works on Unix but not Windows. Alternatives include mysqldump
and MySQL Enterprise Backup.

* The timed_mutexes system variable has no effect and is
deprecated.

Bugs Fixed

* Important Change; Replication: A DROP TABLE statement may be
divided into multiple statements before it is sent to the
binary log if it contains regular (not temporary) tables and
temporary tables, or if it contains temporary tables using
both transactional and non-transactional storage engines. Now,
when using GTIDs, DROP TABLE statements affecting these
combinations of tables are no longer allowed unless the value
of the gtid_next system variable is AUTOMATIC. This is
because, with GTIDs enabled on the server, issuing a DROP
TABLE in the cases just described while having only one GTID
associated with each statement (the SQL thread does this
following SET gtid_next='uuid:number') causes problems when
there are not enough GTIDs for assignment to all the resulting
statements following the division of the original DROP TABLE.
A DROP TABLE statement might be split due to the behavior of
the statement with respect to the current transaction varying,
depending on table characteristics, as follows:

+ DROP TABLE of a regular (not temporary) table is
committed immediately

+ DROP TABLE of a temporary table using a transactional
storage engine is committed with the current transaction
(following COMMIT)

+ DROP TABLE of a temporary table that uses a
nontransactional storage engine is committed immediately
Naming all three of these types of tables in a single DROP
TABLE statement causes the MySQL server to divide the original
statement into three separate DROP TABLE statements in the
binary log. If GTIDs are enabled but the value of gtid_next is
not AUTOMATIC, issuing a DROP TABLE statement that mixes any
of the table types described previously causes the server to
have an insufficient number of GTIDs to write with all of the
resulting statements into the binary log. In addition, DROP
TABLE IF EXISTS is always written in the binary log for all
tables specified in the statement, even if some or all of the
tables do not exist.
Because temporary tables are handled differently by DROP TABLE
depending on whether they use a transactional or
nontransactional storage engine, any tables named by a DROP
TEMPORARY TABLE statement that do not exist are assumed to be
transactional. This means that, if a DROP TEMPORARY TABLE with
two nontransactional temporary tables is issued on the master,
it would writes only one DROP TABLE statement naming both
tables. If one of the temporary tables no longer exists on the
slave, then, when the SQL thread executes the statement, it
tries to divide it into multiple statements due to it
affecting a nontransactional (but existing) temporary table
and a nonexistent transactional temporary table; this leads to
problems because the SQL thread has only one GTID for the
original DROP TABLE statement but must write two DROP TABLE
statements in the binary log.
In addition, when the slave dropped temporary tables after
detecting that the master had restarted, it logged one DROP
TABLE statement per pseudo-thread and per database, but
combined temporary tables using transactional and
nontransactional storage engines in a single DROP TABLE
statement.
Now, we throw an error in the client session if gtid_next is
set to a uuid:number value and a DROP TABLE statement is
issued mixing any of the table types described previously.
In addition, we now group the nonexistent temporary tables and
assume them to be transactional only if at least one
transactional temporary table is dropped by the statement. If
no transactional temporary tables are dropped, any nonexistent
temporary tables are assumed to be nontransactional temporary
tables.
The slave now also handles dropping of temporary tables
correctly in the event of the restart by the master. (Bug
#17620053)

* InnoDB: Opening a parent table that has thousands of child
tables could result in a long semaphore wait condition. (Bug
#18806829)

* InnoDB: For single item full-text searches, deleted documents
were included in inverse document frequency (IDF)
calculations. (Bug #18711306, Bug #72548)

* InnoDB: On mysqld start, specifying multiple data files using
the innodb_data_file_path option would return a Space id in
fsp header error after data is written to the second file.
(Bug #18767811)

* InnoDB: A DELETE operation on a table with full-text search
indexes raised an assertion. (Bug #18683832)
References: See also Bug #14639605.

* InnoDB: When calling the memcached flush_all command, InnoDB
attempts to initialize a connection and a transaction. If the
transaction is in TRX_STATE_NOT_STARTED state, InnoDB would
fail to set CONN_DATA->CRSR_TRX to NULL, resulting in a
serious error. (Bug #18652854)

* InnoDB: When InnoDB is built as a shared library, attempting
to load the InnoDB full-text search (FTS) INFORMATION_SCHEMA
plugin would fail with a Can't open shared library
'ha_innodb.so' error. (Bug #18655281, Bug #70178)

* InnoDB: A regression introduced in MySQL 5.6.5 would cause
full-text search index tables to be created in the system
tablespace (space 0) even though innodb_file_per_table was
enabled. (Bug #18635485)

* InnoDB: The InnoDB memcached plugin would call plugin_del
without acquiring the lock_plugin mutex. This bug fix also
addresses a race condition in ib_cursor_delete_row. (Bug
#18409840)

* InnoDB: The fix for Bug#16418661 added superfluous
buf_flush_list() logic to InnoDB startup code. (Bug #17798076,
Bug #70899)

* InnoDB: A race condition in fts_get_next_doc_id resulted in
Duplicate FTS_DOC_ID and Cannot find index FTS_DOC_ID_INDEX in
InnoDB index translation table errors. (Bug #17447086, Bug
#70311)
References: See also Bug #16469399.

* InnoDB: Due to differences in memory ordering on different
processor types, some mutex and read-write lock flags were not
read consistently. (Bug #11755438, Bug #47213)

* Partitioning: Selecting from a table having multiple columns
in its primary key and partitioned by LIST COLUMNS(R), where R
was the last (rightmost) column listed in the primary key
definition, returned an incorrect result. (Bug #17909699, Bug
#71095)

* Replication: mysqlbinlog --raw did not check for errors caused
by failed writes, which could result in silent corruption of
binary logs. Now in such cases it stops with an error. (Bug
#18742916, Bug #72597)

* Replication: When a slave worker thread tried to execute a
statement that was too large, the resulting error caused a
crash. Now in such cases, the error is truncated to fit the
size of the buffer. (Bug #18563480)

* Replication: When using row-based replication, updating or
deleting a row on the master that did not exist on the slave
led to failure of the slave when it tried to process the
change. This problem occurred with InnoDB tables lacking a
primary key. (Bug #18432495, Bug #72085)

* Replication: Quotation marks were not always handled correctly
by LOAD DATA INFILE when written into the binary log. (Bug
#18207212, Bug #71603)

* Replication: Beginning in MySQL 5.6.20, when a user specified
AUTO_INCREMENT value falls outside of the range between the
current AUTO_INCREMENT value and the sum of the current and
number of rows affected values it is replicated correctly. In
previous versions, an error was generated by the slave even if
the user specified AUTO_INCREMENT value fell outside of the
range. (Bug #17588419, Bug #70583)

* Replication: A group of threads involved in acquiring locks
could deadlock when the following events occurred:

1. Dump thread reconnects from slave; on master, a new dump
thread tries to kill zombie dump threads; having acquired
the thread's LOCK_thd_data, it is about to acquire
LOCK_log.

2. Application thread executing show binary logs, having
acquired LOCK_log and about to acquire LOCK_index.

3. Application thread executing PURGE BINARY LOGS; having
acquired LOCK_index, it is about to acquire
LOCK_thread_count.

4. Application thread executing SHOW PROCESSLIST (or SELECT

* FROM INFORMATION_SCHEMA.PROCESSLIST), having acquired
LOCK_thread_count and about to acquire the zombie dump
thread's LOCK_thd_data.
This leads to the 4 threads deadlocking in the same order
which the threads have been listed here.
This problem arises because there are ordering rules for
LOCK_log and LOCK_index, as well as rules for ordering
LOCK_thread_count and LOCK_thd_data, but there are no rules
for ordering across these two sets of locks. This was because
the internal mysqld_list_processes() function invoked by SHOW
PROCESSLIST acquired LOCK_thread_count for the complete
lifetime of the function as well as acquiring and releasing
each thread's LOCK_thd_data. Now this function takes a copy of
the threads from the global thread list and performs its
traversal on these, and only after releasing
LOCK_thread_count. During this traversal, removal from the
global thread list is blocked using LOCK_thd_remove such that
the copies that would otherwise be destroyed by the removal
remain valid during traversal. The locking order following
this fix is shown here:
LOCK_thd_remove -> LOCK_thd_data -> LOCK_log -> LOCK_index -> LOCK_th
read_count
(Bug #17283409, Bug #69954)

* Replication: On Windows, mysqldump failed if the error log
file was deleted (missing) from the active MySQL server. (Bug
#17076131)

* Replication: Client applications should be able to set the
BINLOG_DUMP_NON_BLOCK flag in the initial handshake packet
(COM_BINLOG_DUMP). Clients connecting to a server issuing a
COM_BINLOG_DUMP with the flag unset do not get an EOF when the
server has sent the last event in the binary log, which causes
the connection to block. This flag, which was removed in error
in MySQL 5.6.5, is now restored in the current release.
As part of this fix, a new --connection-server-id option is
added to mysqlbinlog. This option can be used by the client to
test a MySQL server for the presence of this issue. (Bug
#71178, Bug #18000079)

* When a SELECT included a derived table in a join in its FROM
list and the SELECT list included COUNT(DISTINCT), the COUNT()
returned 1 even if the underlying result set was empty. (Bug
#18853696)
References: This bug is a regression of Bug #11760197.

* Enabling optimizer trace could cause a server exit for queries
with a subquery in a HAVING clause. (Bug #18791851)

* SHA and MD5 functions failed for operations using the internal
filename character set and could cause a server exit. (Bug
#18786138)

* Large arguments passed to mysqldump could lead to buffer
overflow and program exit. (Bug #18779944)

* Compiler flags were not passed to DTrace, causing problems for
32-bit builds cross-compiled on 64-bit platforms. (Bug
#18593044)

* ALTER TABLE on a partitioned table could result in the wrong
storage engine being written into the table's .frm file and
displayed in SHOW CREATE TABLE. (Bug #18618561)

* With the max_heap_table_size system variable set to a large
value (20GB), creation of a temporary table or a table using
the MEMORY storage engine caused a server exit. (Bug
#18463911)

* For debug builds, a 0x00 character in a full-text query string
that used the ujis_japanese_ci, utf8mb4_turkish_ci, or
eucjpms_bin collation could raise an assertion. (Bug
#18277305)

* mysqladmin password masked the old password given on the
command line, but not the new password. (Bug #18163964)

* yaSSL code had an off-by-one error in certificate decoding
that could cause buffer overflow.
yaSSL code had an opendir() without a corresponding
closedir(). (Bug #18178997, Bug #17201924)

* For full-text queries on InnoDB tables, attempts to access
deleted document IDs could lead to a server exit. (Bug
#18079671)

* MyISAM temporary files could be used to mount a code-execution
attack. (Bug #18045646)

* For queries that selected from the Performance Schema
events_statements_current table, adding an ORDER BY clause
could produce incorrect results. (Bug #17729044)

* If a query had both MIN()/MAX() and
aggregate_function(DISTINCT) (for example, SUM(DISTINCT)) and
was executed using Loose Index Scan, the result values of
MIN()/MAX() were set improperly. (Bug #17217128)

* For UNION statements, the rows-examined value was calculated
incorrectly. This was manifest as too-large values for the
ROWS_EXAMINED column of Performance Schema statement tables
(such as events_statements_current). (Bug #17059925)

* Clients could determine based on connection error message
content whether an account existed. (Bug #16513435, Bug
#17357528)

* An assertion could be raised when creating a index on a prefix
of a TINYBLOB or GEOMETRY column in an InnoDB column. (Bug
#16368875, Bug #18776592, Bug #17665767)

* Use of a nonmultibyte algorithm for skipping leading spaces in
multibyte strings could cause a server exit. (Bug #12368495,
Bug #18315770)

* For a view defined on a UNION, the server could create an
invalid view definition. (Bug #65388, Bug #14117018, Bug
#72018, Bug #18405221)

* Configuring with cmake -DWITHOUT_SERVER to build clients
without the server failed for builds outside of the source
tree. (Bug #66000, Bug #14367046)

* With big_tables enabled, queries that used COUNT(DISTINCT) on
a simple join with a constant equality condition on a
non-duplicate key returned incorrect results. (Bug #52582, Bug
#11760197)
References: See also Bug #18853696.

* Deadlock could occur if three threads simultaneously performed
INSTALL PLUGIN, SHOW VARIABLES, and mysql_change_user(). (Bug
#71236, Bug #18008907, Bug #72870, Bug #18903155)

* mysql_config_editor exited when given an empty argument to the
--login-path option. (Bug #71837, Bug #18311024, Bug
#18830493)

* MySQL did not compile with Bison 3. A workaround is to
downgrade to Bison 2. (Bug #71250, Bug #18017820, Bug
#18978946)

* Uninstalling and reinstalling semisynchronous replication
plugins while semisynchronous replication was active caused
replication failures. The plugins now check whether they can
be uninstalled and produce an error if semisynchronous
replication is active. To uninstall the master-side plugin,
there must be no semisynchronous slaves. To uninstall the
slave-side plugin, there must be no semisynchronous I/O
threads running. (Bug #70391, Bug #17638477)

* If there was a predicate on a column referenced by MIN() or
MAX() and that predicate was not present in all the
disjunctions on key parts earlier in the compound index, Loose
Index Scan returned an incorrect result. (Bug #71097, Bug
#17909656)

* Client auto-reconnect did not work for clients linked against
libmysqlclient, even with MYSQL_OPT_RECONNECT enabled. (Bug
#70026, Bug #17309863)

* Upgrades using RPM packages could change the ownership of an
installation directory. (Bug #71715, Bug #18281535)

* Proxy users were unable to execute statements if the proxied
user password had expired. (Bug #71337, Bug #18057562)

* A new CMake option, SUNPRO_CXX_LIBRARY, enables linking
against libCstd instead of stlport4 on Solaris 10 or later.
This works only for client code because the server depends on
C++98. Example usage:
cmake -DWITHOUT_SERVER=1 -DSUNPRO_CXX_LIBRARY=Cstd
(Bug #72352, Bug #18605389)

* File permissions and line endings of several test and
configuration files were made more consistent to avoid
warnings from package checkers. (Bug #68521, Bug #16415173,
Bug #16395459, Bug #68517, Bug #16415032, Bug #71112, Bug
#17919313, Bug #71113, Bug #17919422)

On Behalf of the MySQL/ORACLE RE Team,

Akhil Mohan






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