Dear MySQL users,
MySQL Server 5.6.13, a new version of the popular Open Source
Database Management System, has been released. MySQL 5.6.13 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 5.6.13 on new servers or upgrading
to MySQL 5.6.13 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-5-6-13.html
Enjoy!
Changes in MySQL 5.6.13 (2013-07-31)
A known limitation of this release:
Note
On Microsoft Windows, MySQL Installer will not upgrade MySQL
Enterprise Backup (MEB) 3.8.1 to 3.8.2 (latest version). A
workaround is to uninstall MEB 3.8.1 and then install MEB 3.8.2
(latest version) with MySQL Installer.
Functionality Added or Changed
* Important Change; Replication: By default, when promoting
integers from a smaller type on the master to a larger type on
the slave (for example, from a SMALLINT column on the master
to a BIGINT column on the slave), the promoted values are
treated as though they are signed. Now in such cases it is
possible to modify or override this behavior using one or both
of ALL_SIGNED, ALL_UNSIGNED in the set of values specified for
the slave_type_conversions server system variable. For more
information, see Row-based replication: attribute promotion
and demotion
(http://dev.mysql.com/doc/refman/5.6/en/replication-features-differing-tables.html)
#replication-features-attribute-promotion)
, as well as the description of the variable. (Bug #15831300)
* Previously, program options could be specified in full or as
any unambiguous prefix. For example, the --compress option
could be given to mysqldump as --compr, but not as --comp
because the latter is ambiguous. Option prefixes now are
deprecated. They can cause problems when new options are
implemented for programs. A prefix that is currently
unambiguous might become ambiguous in the future. If an
unambiguous prefix is given, a warning now occurs to provide
feedback. For example:
Warning: Using unique option prefix compr instead of compress is
deprecated and will be removed in a future release. Please use the
full name instead.
Option prefixes are no longer supported in MySQL 5.7; only
full options are accepted. (Bug #16996656)
* The C API libmysqlclient shared-library .so files now have
version 18.1.0 (up from version 18.0.0 used in MySQL 5.5).
(Bug #16809055)
* In batch mode, mysql formatted result status messages such as
""Query OK, 1 row affected"" but did not print them. Now these
messages are not formatted. (Bug #69486, Bug #16971432)
Bugs Fixed
* Performance; Important Change; InnoDB: InnoDB would fail to
open a tablespace that has multiple data files. This removes
the known limitation that was in MySQL Server 5.6.12. (Bug
#17033706, Bug #69623)
* Performance; InnoDB: A code regression introduced in MySQL 5.6
negatively impacted DROP TABLE and ALTER TABLE performance.
This could cause a performance drop between MySQL Server 5.5.x
and 5.6.x. (Bug #16864741, Bug #69316)
* Performance; InnoDB: When innodb_thread_concurrency is set to
a non-zero value, there was a possibility that all
innodb_concurrency_tickets would be released after each row
was read, resulting in a concurrency check after each read.
This could impact performance of all queries. One symptom
could be higher system CPU usage. We strongly recommend that
you upgrade to MySQL Server 5.6.13 if you use this setting.
This could cause a performance drop between MySQL Server 5.5.x
and 5.6.x. (Bug #68869, Bug #16622478)
* Incompatible Change: It is possible for a column DEFAULT value
to be valid for the sql_mode value at table-creation time but
invalid for the sql_mode value when rows are inserted or
updated. Example:
SET sql_mode = '';
CREATE TABLE t (d DATE DEFAULT 0);
SET sql_mode = 'NO_ZERO_DATE,STRICT_ALL_TABLES';
INSERT INTO t (d) VALUES(DEFAULT);
In this case, 0 should be accepted for the CREATE TABLE but
rejected for the INSERT. However, the server did not evaluate
DEFAULT values used for inserts or updates against the current
sql_mode. In the example, the INSERT succeeds and inserts
'0000-00-00' into the DATE column.
The server now applies the proper sql_mode checks to generate
a warning or error at insert or update time.
A resulting incompatibility for replication if you use
statement-based logging (binlog_format=STATEMENT) is that if a
slave is upgraded, a nonupgraded master will execute the
preceding example without error, whereas the INSERT will fail
on the slave and replication will stop.
To deal with this, stop all new statements on the master and
wait until the slaves catch up. Then upgrade the slaves
followed by the master. Alternatively, if you cannot stop new
statements, temporarily change to row-based logging on the
master (binlog_format=ROW) and wait until all slaves have
processed all binary logs produced up to the point of this
change. Then upgrade the slaves followed by the master and
change the master back to statement-based logging. (Bug
#68041, Bug #16078943)
* MySQL Cluster: CREATE LOGFILE GROUP failed with a syntax error
when INITIAL_SIZE, UNDO_BUFFER_SIZE, or both options were
specified. (Bug #13116514)
* InnoDB: The server would crash during a memcached set
operation. The failure was due to a padded length value for a
utf8 char column. During a memcached update operation, a field
from an old tuple would be copied with a data length that was
less than the padded utf8 char column value. This fix ensures
that old tuples are not copied. Instead, a new tuple is
created each time. (Bug #16875543)
* InnoDB: When CHECK TABLE found a secondary index that
contained the wrong number of entries, it would report an
error but not mark the index as corrupt. CHECK TABLE now marks
the index as corrupt when this error is encountered, but only
the index is marked as corrupt, not the table. As a result,
only the index becomes unusable until it is dropped and
rebuilt. The table is unaffected. (Bug #16914007)
* InnoDB: InnoDB would attempt to gather statistics on partially
created indexes. (Bug #16907783)
* InnoDB: A full-text search using the IN BOOLEAN MODE
(http://dev.mysql.com/doc/refman/5.6/en/fulltext-boolean.html)
modifier would result in an assertion failure. (Bug #16927092)
References: This bug is a regression of Bug #16516193.
* InnoDB: The two INFORMATION_SCHEMA tables for the InnoDB
buffer pool could show an invalid page type for read-fixed
blocks. This fix will show the unknown page type for blocks
that are I/O-fixed for reading. (Bug #16859867)
* InnoDB: During an insert buffer merge, InnoDB would invoke
lock_rec_restore_from_page_infimum() on a potentially invalid
record pointer. (Bug #16806366)
* InnoDB: During an insert buffer merge, InnoDB would invoke
lock_rec_restore_from_page_infimum() on a potentially invalid
record pointer. (Bug #16806366)
* InnoDB: The innodb_rwlock_x_spin_waits item in the
INFORMATION_SCHEMA.INNODB_METRICS table would show the same
value as the innodb_rwlock_x_os_waits item. (Bug #16798175)
* InnoDB: A memory leak would occur when inserting or replacing
a row in a full-text search index on a table with more than 96
columns. (Bug #16809167)
* InnoDB: In debug builds, an assertion could occur in
OPT_CHECK_ORDER_BY when using binary directly in a search
string, as binary may include NULL bytes and other
non-meaningful characters. This fix will remove non-meaningful
characters before the search is run. (Bug #16766016)
* InnoDB: The page_zip_validate() consistency check would fail
after compressing a page, in page_zip_compress(). This problem
was caused by page_zip_decompress(), which would fail to set
heap_no correctly when a record contained no user data bytes.
A record with no user data bytes occurs when, for example, a
primary key is an empty string and all secondary index fields
are NULL or an empty string. (Bug #16736929)
* InnoDB: A race condition would occur between ALTER TABLE ...
ADD KEY and INSERT statements, resulting in an "Unable to
Purge a Record" error. (Bug #16628233)
* InnoDB: A full-text search that returns large result sets
would consume an excessive amount of memory due to use of a
red-black tree for holding full-text search results. This fix
reduces and imposes a limit on memory consumption. If the
limit is exceeded, a message is returned indicating that the
full-text search query exceeds the maximum allowed memory.
(Bug #16625973)
* InnoDB: Restarting InnoDB in read-only mode and running a
workload would occasionally return a global_segment <
os_aio_n_segments assertion. (Bug #16362046)
* InnoDB: When the InnoDB shutdown mode (innodb_fast_shutdown)
is set to 2 and the master thread enters the flush loop, the
thread would not be able to exit under some circumstances.
This could lead to a shutdown hang. (Bug #16411457)
* InnoDB: While printing a UTF-8 table name, InnoDB would
truncate the table name, resulting in an incomplete buffer and
subsequent Valgrind error. This bug fix also addresses an
incorrect debugging error message. (Bug #16066351)
* InnoDB: Attempting to create a table while in innodb_read_only
mode would result in the following error: ERROR 1015 (HY000):
Can't lock file (errno: 165 - Table is read only). (Bug
#15963619)
* InnoDB: Due to a resource related bug, creating numerous
tables that have a simple a full-text search index would cause
excessive memory usage. This fix adds a global configuration
parameter to limit the total memory size that full-text search
indexes can use. If the global memory limit is reached by an
index operation, a force sync is triggered. (Bug #14834698,
Bug #16817453)
* InnoDB: In the error log, a full-text search index would be
reported missing from the data dictionary during a TRUNCATE
TABLE operation. After restarting mysqld, the following InnoDB
error would be reported: "InnoDB: Error: trying to load index
idx13 for table test/g1 but the index tree has been freed.."
(Bug #12429565)
* InnoDB: Creating a table with a comment or default textual
value containing an apostrophe that is escaped with a
backslash would sometimes cause the InnoDB storage engine to
omit foreign key definitions. (Bug #61656, Bug #12762377)
* InnoDB: Setting foreign_key_checks=0 and running ALTER TABLE
to change the character set of foreign key columns for a
database with multiple tables with foreign key constraints
would leave the database in an inconsistent state. Subsequent
ALTER TABLE operations (using the COPY algorithm) with
foreign_key_checks=1 would fail due to the detected
inconsistency. Reversion of the partially executed ALTER TABLE
operation would also fail, resulting in the loss of the table
being altered. When running the same ALTER TABLE operation
with a RENAME clause, the inconsistency would not be detected
but if the ALTER TABLE operation failed for some other reason,
reversion of the partially executed ALTER TABLE would fail
with the same result.
The bug fix temporarily disables foreign_key_checks while the
previous table definition is restored. (Bug #65701, Bug
#14227431)
* InnoDB: Successive deletes in descending key order would lead
to under-filled InnoDB index pages. When an InnoDB index page
is under-filled, it is merged with the left or right sibling
node. The check performed to determine if a sibling node is
available for merging was not functioning correctly. (Bug
#68501, Bug #16417635)
* InnoDB: The pthread_mutex, commit_threads_m, which was
initialized but never used, has been removed from the code
base. (Bug #60225, Bug #11829813)
* InnoDB: When running an InnoDB full-text search in boolean
mode, prefixing an asterisk (*) to a search string ('*string')
would result in an error whereas for MyISAM, a prefixed
asterisk would be ignored. To ensure compatibility between
InnoDB and MyISAM, InnoDB now handles a prefixed asterisk in
the same way as MyISAM. (Bug #68948, Bug #16660607)
* InnoDB: The row_check_index_for_mysql method, which checks for
NULL fields during an index scan or CHECK TABLE operation,
would iterate unnecessarily. Thanks to Po-Chun Chang for the
patch to correct this issue. (Bug #69377, Bug #16896647)
* Partitioning: When upgrading to MySQL 5.5.31 or higher, a
message is written into the output of mysql_upgrade when
encountering a partitioned table for which the ALGORITHM
option is required to maintain binary compatibility with the
original; the message includes the ALTER TABLE statement
required to make the change. For such a table having a
sufficiently large number of partitions, the message was
truncated with an error before the complete ALTER TABLE
statement could be written. (Bug #16589511)
* Partitioning: When a range specified in the WHERE condition of
a query against a table partitioned by RANGE entirely within
that of one of the partitions, the next partition was also
checked for rows although it should have been pruned away.
Suppose we have a range-partitioned table t created using the
following SQL statement:
CREATE TABLE t (
id INT AUTO_INCREMENT,
dt DATETIME,
PRIMARY KEY (dt,id),
UNIQUE KEY (id,dt)
)
PARTITION BY RANGE COLUMNS(dt) (
PARTITION p0 VALUES LESS THAN ('2013-01-01'),
PARTITION p1 VALUES LESS THAN ('2013-01-15'),
PARTITION p2 VALUES LESS THAN ('2013-02-01'),
PARTITION p3 VALUES LESS THAN ('2013-02-15'),
PARTITION pmax VALUES LESS THAN (MAXVALUE)
);
An example of a query that exhibited this issue when run
against t is shown here:
SELECT COUNT(*) FROM t
WHERE dt >= '2013-02-01' AND dt < '2013-02-15';
In this case, partition pmax was checked, even though the
range given in the WHERE clause lay entirely within partition
p3. (Bug #16447483)
* Partitioning: When dropping a partitioned table, the table's
.par file was deleted first, before the table definition or
data. This meant that, if the server failed during the drop
operation, the table could be left in an inconsistent state in
which it could neither be accessed nor dropped.
The fix for this problem makes the following changes:
+ Now, when dropping a partitioned table, the table's .par
file is not removed until all table data has been
deleted.
+ When executing DROP TABLE of a partitioned table, in the
event that its .par file is determined to be missing, the
table's .frm file is now immediately deleted, in effect
forcing the drop to complete.
(Bug #13548704, Bug #63884)
* Replication: The condition leading to the issue fixed in Bug
#16579083 continued to raise an error even though the
condition itself no longer cause the issue to occur. (Bug
#16931177, Bug #69369)
References: See also Bug #16271657, Bug #16491597, Bug #68251,
Bug #68569.
* Replication: When rpl_semi_sync_master_timeout was set to an
extremely large value, semi-synchronous replication became
very slow, especially when many sessions were working in
parallel. It was discovered that the code to calculate this
timeout was inside the wait loop itself, with the result that
an increase in the value of rpl_semi_sync_master_timeout
caused repeated iterations. This fix improves the method used
to calculate wakeup times, and moves it outside of the wait
loop, so that it is executed one time only. (Bug #16878043,
Bug #69341)
* Replication: It was possible to cause a deadlock after issuing
FLUSH TABLES WITH READ LOCK by issuing STOP SLAVE in a new
connection to the slave, then issuing SHOW SLAVE STATUS using
the original connection.
The fix for this includes the addition of the
rpl_stop_slave_timeout system variable, to control the time in
seconds to wait for slave to stop after issuing STOP SLAVE
before returning a warning. (Bug #16856735)
* Replication: Some expressions employing variables were not
handled correctly by LOAD DATA. (Bug #16753869)
* Replication: In some circumstances, the message in the
Last_Error column from the output of SHOW SLAVE STATUS
referred to GTID_NEXT_LIST although this variable is not
currently implemented (the name is reserved for possible
future use). Now in such cases the error message no longer
refers to this variable. (Bug #16742886, Bug #69096)
References: See also Bug #16715809, Bug #69045.
* Replication: The error displayed by SHOW SLAVE STATUS when a
worker thread fails to apply an event contained no event
coordinate information. The GTID for the event's group was
also not shown. Now in such cases, the text shown for
Last_SQL_Error is prefixed with the (physical) master binary
log coordinates, as well as the value of gtid_next when this
has been set. (Bug #16594095)
* Replication: Linker errors occurred if the header file
log_event.h was included in an application containing multiple
source files, because the file rpl_tblmap.cc was included in
log_event.h. This fix moves the inclusion of rpl_tblmap.cc
into the source files that use log_event.h. (Bug #16607258)
* Replication: The warning issued when specifying MASTER_USER or
MASTER_PASSWORD with CHANGE MASTER TO was unclear for a number
of reasons, and has been changed to read, Storing MySQL user
name or password information in the master info repository is
not secure and is therefore not recommended. Please consider
using the USER and PASSWORD connection options for START
SLAVE; see 'START SLAVE Syntax' in the MySQL Manual for more
information. (Bug #16460123, Bug #16461303, Bug #68602, Bug
#68599)
* Replication: After a transaction was skipped due to its GTID
already having been logged, all remaining executed
transactions were incorrectly skipped until gtid_next was
pointed to a different GTID.
To avoid this incorrect behavior, all transactions---even
those that have been skipped---are marked as undefined when
they are commited or rolled back, so that an error is thrown
whenever a second transaction is executed following the same
SET @@session.gtid_next statement. (Bug #16223835)
* Replication: After the client thread on a slave performed a
FLUSH TABLES WITH READ LOCK and was followed by some updates
on the master, the slave hung when executing SHOW SLAVE
STATUS. (Bug #68460, Bug #16387720)
* For debug builds, improper use of SAFE_MUTEX within dbug.c
caused different code areas to have different ideas about size
and contents of a mutex. This could result in out-of-bounds
memory writes. (Bug #16945343)
* Sql_condition::set_subclass_origin() could perform an
out-of-bounds read. (Bug #16969091)
* Initialization of keycache_* variables (see Multiple Key
Caches
(http://dev.mysql.com/doc/refman/5.6/en/multiple-key-caches.html))
during server startup could write to incorrect memory.
Bug #16945503)
* Reads from message buffers for closed connections could occur.
(Bug #17003702)
* The server could exit while using a cursor to fetch rows from
a UNION query. (Bug #16983143)
* The range optimizer incorrectly assumed that any geometry
function on a spatial index returned rows in ROWID order,
which could result in incorrect query results. (Bug #16960800)
* The server did excessive locking on the LOCK_active_mi and
active_mi->rli->data_lock mutexes for any SHOW STATUS LIKE
'pattern' statement, even when the pattern did not match
status variables that use those mutexes
(Slave_heartbeat_period, Slave_last_heartbeat,
Slave_received_heartbeats, Slave_retried_transactions,
Slave_running). Now attempts to show those variables do not
lock those mutexes. This might result is slightly stale data,
but better performance. (Bug #16904035)
* Full-text phrase search in InnoDB tables could read incorrect
memory. (Bug #16885178)
* It was not possible to keep several major versions of MySQL in
the same yum repository. (Bug #16878042)
* The Performance Schema could spawn a thread using incorrect
instrumentation information. (Bug #16939689)
* INSERT ... ON DUPLICATE KEY UPDATE could cause a server exit
if a column with no default value was set to DEFAULT. (Bug
#16756402)
References: This bug is a regression of Bug #14789787.
* The code base was modified to account for new warning checks
introduced by gcc 4.8. (Bug #16729109)
* Compiling failed with -DMY_ATOMIC_MODE_RWLOCKS=1 or on
platforms on which MySQL did not support lockless atomic
operations (such as ARM). (Bug #16736461)
* In a prepared statement or stored routine, if the HAVING
clause of a subquery referenced some column of the GROUP BY of
the parent query, the server could exit. (Bug #16739050)
* The read-only open_files_limit system variable did not show
maximum number of open files the mysqld process could have,
but instead the number that was requested after adjusting the
--open-files-limit command-line option. (Bug #16657588)
* Some rows for a session could be missing sporadically from the
Performance Schema session_connect_attrs table while the
session was executing a workload. (Bug #16576980)
* The server could make the wrong decision about whether an
account password was expired. (Bug #16604641)
* Upgrading from community SLES RPM packages to commercial
packages for the same MySQL version failed with conflict
errors. (Bug #16545296)
* A full-text search syntax error failed to print to standard
output. (Bug #16429688, Bug #16765397)
* Unlike MyISAM, InnoDB does not support boolean full-text
searches on nonindexed columns, but this restriction was not
enforced, resulting in queries that returned incorrect
results. (Bug #16434374)
* If the optimizer was using a loose index scan, the server
could exit while attempting to create a temporary table. (Bug
#16436567)
* Incorrect results or a server exit could be caused by a
reference to an aggregated expression inside a nested
subquery, where the aggregated expression was evaluated in a
query block more than two levels outer to the reference. (Bug
#16436383)
* In debug builds, failure in the range optimizer for an
ER_LOCK_DEADLOCK or ER_LOCK_WAIT_TIMEOUT error could go
undetected and cause an assertion to be raised when a response
was sent to the client. In release builds, this problem
manifested as clients receiving an OK for a statement that had
failed. (Bug #16366994, Bug #16247110)
* An assertion could be raised when creating a index on a prefix
of a TINYBLOB column in an InnoDB column. (Bug #16368875)
* A server exit could occur for queries of the form SELECT
(SELECT 1 FROM t1) IN (SELECT a FROM t1) when attempting to
evaluate the constant left-hand argument to the IN subquery
predicate. (Bug #16369522)
* No warning was generated if a duplicate index existed after
dropping a column associated with a multiple-column index.
(Bug #16315351)
* SELECT DISTINCT with WITH ROLLUP could result in a Duplicate
entry 'NULL' for key '<auto_key>' error. (Bug #16314835)
* The server could exit in do_copy_not_null() due to an improper
NULL-value check. (Bug #16316564)
* Transforming some subqueries that select temporal or BIGINT
types or to a semijoin caused a server exit on the second
execution of prepared statements or stored programs. (Bug
#16319671)
* The usual failed-login attempt accounting was not applied to
failed COM_CHANGE_USER commands. (Bug #16241992)
* A user variable referenced during execution of a prepared
statement is set to memory that is freed at the end of
execution. A second execution of the statement could result in
Valgrind warnings when accessing this memory. (Bug #16119355)
* Misoptimization of left expressions in prepared statements
could cause a server exit. (Bug #16095534)
* The optimizer trace could print ranges for key parts that were
not usable for range access. (Bug #14615536)
* When running a query on INFORMATION_SCHEMA.INNODB_BUFFER_PAGE
that requested table_name and index_name values, query results
would include index pages without table_name or index_name
values. (Bug #14529666)
* Several COM_xxx commands in the client-server protocol did not
have length checks for incoming network packets, which could
result in various problems for malformed input. (Bug
#14525642)
* Passwords in statements were not obfuscated before being
written to the audit log. (Bug #14536456)
* With the thread pool plugin in use, normal connection
termination caused the Aborted_clients status variable to be
incremented. (Bug #14081240)
* On Windows, command-line options of the form
--opt_name="opt_value" worked but --opt_name='opt_value' did
not.
On all platforms, for Performance Schema options of the form
--performance_schema_instrument="instrument=value", invalid
instrument names now are rejected. (Bug #13955232)
* MySQL Installer, if run in custom install or change mode,
offered installation options that had no effect. (Bug
#12928601)
* Incorrect results could be returned from queries that used
several aggr_func(DISTINCT) functions (where aggr_func() is an
aggregate function such as COUNT()) when these referred to
different columns of the same composite key. (Bug #12328597)
* If an UPDATE containing a subquery caused a deadlock inside
InnoDB, the deadlock was not properly handled by the SQL
layer. The SQL layer then tried to unlock the row after InnoDB
rolled back the transaction, raising an assertion inside
InnoDB. (Bug #69127, Bug #16757869)
* Boolean plugin system variables did not behave well on
machines where char is unsigned; some code attempted to assign
a negative value to these. (Bug #59905, Bug #11864205)
* In the absence of SQL_CALC_FOUND_ROWS in the preceding query,
FOUND_ROWS() should return the number of rows in the result
set, but this did not always happen if the query contained
ORDER BY. (Bug #69271, Bug #16827872)
* Unoptimized versions of the xxxkorr() macros in my_global.h
were used on 64-bit x86 processors. (Bug #61179, Bug
#12565703)
* sql-common/client_plugin.c contained a nonportable use of a
va_list parameter. (Bug #62769, Bug #13252623)
* mysqldump assumed the existence of the general_log and
slow_log tables in the mysql database. It failed if invoked to
dump tables from an older server where these tables do not
exist. (Bug #65670, Bug #14236170)
* Full-text search on InnoDB tables failed on searches for words
containing apostrophes. (Bug #69216, Bug #16801781)
* Full-text search on InnoDB tables failed on searches for
literal phrases combined with + or - operators. (Bug #68720,
Bug #16516193)
* Optimizations that used extended secondary keys (see Use of
Index Extensions
(http://dev.mysql.com/doc/refman/5.6/en/index-extensions.html)
) worked only for InnoDB, even for storage engines with the
requisite underlying capabilities. (Bug #68469, Bug #16391678)
* 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)
* mysql_install_db incorrectly tried to create the
mysql.innodb_table_stats and mysql.innodb_index_stats tables
if InnoDB was not available. (Bug #68438, Bug #16369955)
* If one session had any metadata lock on a table, another
session attempting CREATE TABLE [IF NOT EXISTS] for the same
table would hang. This occurred due to an attempt in the
second session to acquire an exclusive metadata lock on the
table before checking whether the table already existed. An
exclusive metadata lock is not compatible with any other
metadata locks, so the session hung for the lock timeout
period if another session had the table locked.
Now the server attempts to acquire a shared metadata lock on
the table first to check whether it exists, then upgrade to an
exclusive lock if it does not. If the table does exist, an
error occurs for CREATE TABLE and a warning for CREATE TABLE
IF NOT EXISTS. (Bug #63144, Bug #13418638)
* Attempts to build from a source RPM package could fail because
the build process attempted to refer to a pb2user that might
not exist. (Bug #64641, Bug #13865797, Bug #69339, Bug
#16874980)
* A typo in cmake/dtrace.cmake prevented DTrace support from
being enabled by -DENABLE_DTRACE-on. (Bug #60743, Bug
#12325449)
* When an internal buffer was too small for the workload, the
Performance Schema could spend a lot of time in an internal
spin loop attempting to allocate a memory buffer, and fail.
(Bug #69382, Bug #16945618)
* Some LEFT JOIN queries with GROUP BY could return incorrect
results. (Bug #68897, Bug #16620047)
References: This bug is a regression of Bug #11760517.
* For queries with ORDER BY ... LIMIT, the optimizer could
choose a nonordering index for table access. (Bug #69410, Bug
#16916596)
* When selecting a union of an empty result set (created with
WHERE 1=0 or WHERE FALSE) with a derived table, incorrect
filtering was applied to the derived table. (Bug #69471, Bug
#16961803)
References: This bug is a regression of Bug #15848521.
* Comparison of a DATETIME value and a string did not work
correctly for the utf8_unicode_ci collation. (Bug #68795, Bug
#16567381)
On Behalf of the MySQL/ORACLE RE Team,
Sunanda Menon
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