Beginning with MySQL 5.6.7, Oracle no longer provides binaries for Mac OS X 10.5, Debian 5, RHEL/OL 4, SLES 10, FreeBSD 7, Windows XP, or Windows 2003.
This release continues the process begun in MySQL 5.6.6 of making changes to the default values of server parameters. The motivation for these changes is to provide better out-of-box performance and to reduce the need for database administrators to change settings manually. These changes are subject to revision in future releases as we gain feedback.
The following table summarizes changes to defaults. Any of these default settings can be overridden by specifying an explicit value at server startup.
|Parameter||Old Default||New Default|
Functionality Added or Changed
A new setting
O_DIRECT_NO_FSYNC was added to
configuration option. This setting is similar to
O_DIRECT, but omits the subsequent
fsync() call. Suitable for some filesystems
but not others.
(Bug #11754304, Bug #45892)
Important Change; Partitioning: The maximum number of partitions for a user-partitioned table is increased from 1024 to 8192. (Bug #11755685)
In MySQL 5.6.6,
was deprecated, to be removed in a future release. The same is
now also true for
DELAYED-related status variables
lets you run a MySQL server in read-only mode. You can access
InnoDB tables on read-only media such as a
DVD or CD, or set up a data warehouse with multiple instances
all sharing the same data directory. See
InnoDB for Read-Only Operation for usage details.
You can now select the
compression level for
InnoDB compressed tables, from the familiar
range of 0-9 used by
zlib. The compression
level is controlled by the
configuration option, with a default value of 6:
Increasing the compression level increases CPU overhead, possibly reducing the amount of storage needed for any particular row, reducing the possibility of a compression failure and subsequent page split.
Decreasing the compression level reduces CPU overhead, possibly increasing the amount of storage needed for any particular row, increasing the possibility of a compression failure and subsequent page split.
You can also control whether compressed pages in the buffer pool
are stored in the redo log when an update operation causes pages
to be compressed again. This behavior is controlled by the
configuration option. Turning off logging for compressed pages
reduces the amount of redo data that is generated, possibly
improving throughput. If the compressed page is required during
crash recovery, it is
compressed again at that time.
Each data block in an
contains a certain amount of empty space (padding) to allow
DML operations to modify the row
data without re-compressing the new values. Too much padding can
increase the chance of a compression failure, requiring a page
split, when the data does need to be re-compressed after
extensive changes. The amount of padding can now be adjusted
dynamically, so that DBAs can reduce the rate of compression
failures without re-creating the entire table with new
parameters, or re-creating the entire instance with a different
page size. The associated new configuration options are
InnoDB tables that use
statistics at the index level let DBAs measure whether the
proportion of successful or failed compression operations is
acceptable for a particular combination of table, index,
page size, and
workload. Typically, the
compression failure rate should be less than 10%, particularly
when using a compressed table to handle an OLTP-style workload
Because gathering those statistics could be very time consuming
and would hurt performance negatively, the new tables are
enabled only when the new configuration option
ON. (It is
When MySQL is configured with
-DWITH_SSL=system to build with
OpenSSL, CMake now produces an error if OpenSSL is older than
The server now issues a
Note diagnostic if an
index is created that duplicates an existing index.
(Bug #37520, Bug #11748842)
WITH_SSL option for CMake now
path_name value that
indicates the path name to the OpenSSL installation to use. This
can be useful instead of a value of
when the CMake code detects an older or incorrect installed
OpenSSL version. (Another permitted way to do the same thing is
to set the
CMAKE_PREFIX_PATH option to
(Bug #61619, Bug #12762891)
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.
The MySQL client library now includes SSL support built in. When
linking MySQL client programs, you should no longer specify
References: See also Bug #12762891, Bug #14167227.
multi_range_count system variable
is now deprecated, and will be removed in a future release.
The following items are deprecated and will be removed in a future MySQL release. Where alternatives are shown, applications should be updated to use them.
mysql.host table. New MySQL
5.6 installations will no longer create this table. For
upgrades, mysql_upgrade will check for
this table and issue a warning about it being deprecated if
it is nonempty.
syntax for controlling plugin option
This fix improves the performance of the
InnoDB memcached plugin in
A background thread periodically commits changes made to the
database through memcached API calls.
This commit interval based on time rather than number of
operations lets you increase the value of
without the risk of some changes remaining uncommitted when
DML activity is infrequent. You can control the frequency of
these automatic commits through the
When binary log support is enabled through the
configuration option, you can increase the value of
higher than the default of 1, allowing several DML
operations to be committed together rather than a separate
commit for each one.
Internally, the efficiency of mutexes and table opening/closing was improved for operations involving the memcached plugin.
This fix removes redundant
checksum validation on
pages. The checksum was being
verified both when a compressed page was read from disk and when
it was uncompressed. Now the verification is only performed when
the page is read from disk.
(Bug #14212892, Bug #64170)
On Solaris systems, enabling
lead to a slowdown in event executions on the slave.
References: See also Bug #13897025.
enabled, an internal multiplier representing the number of
events above a certain overrun level in the worker queue was
never reset to zero, even when the excess had been taken care
of; this caused the multiplier to grow without interruption over
time, leading to a slowdown in event executions on the slave.
View definitions (in
.frm files) were not
cached and thus every access to a view involved a file read.
Definitions now are cached for better performance.
Certain instances of subquery materialization could lead to poor
performance. Subquery materialization now is chosen only if it
is less costly than the
transformation. (See Optimizing Subqueries with Subquery Materialization,
and Optimizing Subqueries with
This fix introduces a new flag for the
optimizer_switch system variable named
subquery_materialization_cost_based. If the
on (the default), the optimizer
performs a cost-based choice between subquery materialization
IN -> EXISTS subquery transformation
if either method could be used. If the flag is
off, the optimizer chooses subquery
IN -> EXISTS subquery
transformation, which was the previous behavior.
ALTER TABLE to change the
definition of a foreign key column could cause a loss of
referential integrity. For example, changing a foreign key
column that contained
NULL values to be
NOT NULL caused the
values to be the empty string. Similarly, an
IGNORE that removed rows in a parent table could break
The server now prohibits changes to foreign key columns with the
potential to cause loss of referential integrity. A workaround
is to use
TABLE ... DROP FOREIGN KEY before changing the column
ALTER TABLE ... ADD
FOREIGN KEY afterward.
(Bug #46599, Bug #11754911)
Important Change; Replication: When issued during an ongoing transaction, any of the following statements that are used to control MySQL Replication now cause the transaction to be committed:
For more information, see Statements That Cause an Implicit Commit. (Bug #13858841)
References: See also Bug #14298750, Bug #13627921.
ALTER USER statement cleared
the user password in the
mysql.user table. It
no longer does this.
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)
SELECT from a partitioned
InnoDB table having no primary key
sometimes failed to return any rows where a nonempty result was
expected. In such cases the server also returned the error
Can't find record in
Incorrect key file for table
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)
On Windows systems, a file access error due to an incorrect
MYSQL_DATADIR could cause an
InnoDB assertion error. The error could
persist after restarting MySQL.
The default for the
which was briefly changed to crc32 during the
MySQL 5.6 development cycle, was switched back to
innodb for improved compatibility of
InnoDB data files during a downgrade to an
earlier MySQL version.
When configuring the InnoDB memached plugin system table,
INNODB_MEMCACHE.CONTAINERS, a comma
(“,”) and empty space are used as a delimiter for
mapping multiple columns to a memcached value. This fix allows
the pipe character, (“
also be used as a delimiter.
ALTER TABLE that rebuilds a
table, and in particular,
DROP COLUMN, there were some assertion
failures related to
particularly for tables containing more than one
FULLTEXT index. The fix makes the
ALTER TABLE correctly use or not
use online DDL depending
on the presence of
FULLTEXT indexes. If a
table had a
FULLTEXT index that was dropped,
any restrictions on online DDL for that table remain, due to the
Under certain conditions, the
configuration option now uses the following formula to calculate
a default value:
innodb_io_capacity_max = max(2000, innodb_io_capacity * 2)
The formula only takes affect when you specify a value for
innodb_io_capacity at server
startup and do not specify a value for
formula is not used when setting a value for
TABLE ... DROP FOREIGN KEY ... ALGORITHM=COPY
incorrectly considered the names of
foreign keys to be
Under heavy load of concurrent
DML and queries, an
InnoDB table with a unique index could return
nonexistent duplicate rows to a query.
(Bug #14399148, Bug #66134)
When an error (such as a duplicate key error) was detected
during an online DDL operation, while applying changes made to
the table while an index was being built, MySQL could encounter
an assertion error if the same
TABLE statement also contained any
ALTER TABLE statements for
partitioned tables could cause unnecessary
undo information. As part of
the new online DDL
feature, MySQL minimizes this overhead when practical, or you
can specify the
ALGORITHM=INPLACE clause on
ALTER TABLE statement.
A heavy query workload against an
table with a
FULLTEXT index could cause a
crash. The issue only occurred with some number of queries per
second and some number of concurrent connections.
InnoDB: When an InnoDB table had a system-chosen primary key, based on a unique index on non-nullable columns, an error was issued if one of the primary key columns was altered to be nullable. The message was:
Warning 1082 InnoDB: Table
table_namehas a primary key in InnoDB data dictionary, but not in MySQL!
If an online
CREATE INDEX operation failed,
there was a brief period of time when concurrent
DML operations could fail
because the table was considered to be in an error state.
mysql_install_db command could crash with
an assertion error:
InnoDB: Assertion failure in thread
thread_numin file trx0rseg.cc line 326
The size of the
InnoDB system tablespace was
being capped at 10MB, but during the 5.6 development cycle, the
minimum size of a system tablespace became slightly larger than
The server could crash if a read-only transaction was killed in
a session that contained an
When more than one
InnoDB temporary table was
created and accessed within the same transaction, queries on
those temporary tables could fail with an
This fix addresses several issues regarding
AUTO_INCREMENT columns when adding a column
using online DDL (that
ALGORITHM=INPLACE). Now the
AUTO_INCREMENT_OFFSET value is used properly,
the calculation for the next value is corrected,
INTEGER auto-increment values are
handled correctly, and overflow conditions are detected.
SHOW ENGINE...STATUS command could crash if
an XA transaction was created
using the statement
START TRANSACTION READ
This fix prevents online
DDL operations from conflicting with
foreign key operations
happening simultaneously on the same table. Updates or deletes
NULL clauses in the foreign key definition are blocked
while the online DDL is in progress, because the information
needed in case of a
not be available after the
TABLE statement completes.
A race condition could cause assertion errors during a
DROP TABLE statement for an
InnoDB table. Some internal
InnoDB functions did not correctly determine
if a tablespace was missing; other functions did not handle the
error code correctly if a tablespace was missing.
With the MySQL 5.6 online
DDL feature, an
TABLE statement to add a primary key to an
InnoDB table could succeed, even though the
primary key columns contained duplicate values.
The server could crash with a combination of a transaction with
SERIALIZABLE isolation level,
FLUSH TABLES ... WITH READ LOCK, and a
subsequent query. The error message was:
InnoDB: Failing assertion: prebuilt->stored_select_lock_type != LOCK_NONE_UNSET
When an auto-increment column used a
DOUBLE data type, if the auto-increment value
became very large (larger than the maximum
long long value), subsequent inserts could fail or
cause the server to halt.
(Bug #14145950, Bug #55071)
INSERT into a table after a failed
online DDL operation
could cause an erroneous assertion error:
InnoDB: Failing assertion: prebuilt->trx_id == 0 || prebuilt->trx_id <= last_index->trx_id
The server could hang at startup, during
crash recovery, if
the rollback of previously active transactions conflicted with
the dropping of temporary tables. With this fix,
statistics do not apply to
InnoDB: The server could crash with a signal 8 (division by zero error) due to a race condition while computing index statistics. (Bug #14150372)
Deleting from an
InnoDB table containing a
prefix index, and
subsequently dropping the index, could cause a crash with an
The value of the
NUMBER_PAGES_WRITTEN columns of the
table were set to incorrect values, and the
NUMBER_PAGES_GET column was not being set at
The error message was improved for the case where an
UPDATE failed because the row
included several BLOB values greater than 768 bytes each,
causing the size of a row to exceed half the
page size. The old
message, was misleading; it suggested using BLOBs, when the
768-byte prefix for each BLOB column was the cause of the limit
Error Code 1118: Row size too large. The maximum row size for the used table type, not counting BLOBs, is 8126. You have to change some columns to TEXT or BLOBs
A workaround for the problem was to create the table with the
ROW_FORMAT=COMPRESSED clause, which is now
suggested in the message.
(Bug #13453036, Bug #63507)
InnoDB: The server could crash when updating very large BLOB values, typically 16MB or more. (Bug #13450566)
SELECT ... FOR UPDATE,
UPDATE, or other SQL statement scanned rows
InnoDB table using a
<= operator in
WHERE clause, the next row after the
affected range could also be locked. This issue could cause a
lock wait timeout for a row that was not expected to be locked.
The issue occurred under various isolation levels, such as
READ COMMITTED and
The new online DDL
feature addressed long-standing bugs where
ALTER TABLE statements caused
table rebuilds unnecessarily. This particular bug applied to
changing default values for
(Bug #11753646, Bug #45124)
Various inconsistent behaviors, including tables becoming
inaccessible, were cleaned up for
TABLE statements involving
tables involved in foreign
(Bug #11744929, Bug #5670)
For tables using
PARTITION BY HASH or
PARTITION BY KEY, when the partition pruning
mechanism encountered a multi-range list or inequality using a
column from the partitioning key, it continued with the next
partitioning column and tried to use it for pruning, even if the
previous column could not be used. This caused partitions which
possibly matched one or more of the previous partitioning
columns to be pruned away, leaving partitions that matched only
the last column of the partitioning key.
This issue was triggered when both of the following conditions were met:
The columns making up the table's partitioning key were
used in the same order as in the partitioning key definition
WHERE clause as in the column
WHERE condition used with the last
column of the partitioning key was satisfied only by a
single value, while the condition testing some previous
column from the partitioning key was satisfied by a range of
An example of a statement creating a partitioned table and a query against this for which the issue described above occurred is shown here:
CREATE TABLE t1 ( c1 INT, c2 INT, PRIMARY KEY(c2, c1) ) PARTITION BY KEY() # Use primary key as partitioning key PARTITIONS 2; SELECT * FROM t1 WHERE c2 = 2 AND c1 <> 2;
This issue is resolved by ensuring that partition pruning skips any remaining partitioning key columns once a partition key column that cannot be used in pruning is encountered. (Bug #14342883)
Partitioning: The buffer for the row currently read from each partition used for sorted reads was allocated on open and freed only when the partitioning handler was closed or destroyed. For SELECT statements on tables with many partitions and large rows, this could cause the server to use excessive amounts of memory.
This issue has been addressed by allocating buffers for reads from partitioned tables only when they are needed and freeing them immediately once they are no longer needed. As part of this fix, memory is now allocated for reading from rows only in partitions that have not been pruned (see Partition Pruning). (Bug #13025132)
References: See also Bug #11764622, Bug #14537277.
Replication; Microsoft Windows:
On 64-bit Windows platforms, values greater than 4G for the
system variables were truncated to 4G. This caused
INFILE to fail when trying to load a file larger than
4G in size, even when
was set to a value greater than this.
Updates writing user variables whose values were never set on a
slave while using
cause the slave to fail.
References: This bug was introduced by Bug #14275000.
When the number of multi-threaded slave workers (as determined
by setting the
system variable) was changed when using
mysql.slave_worker_info table did not
reflect the change.
References: See also Bug #13804728, Bug #14550945, Bug #14578740.
greater than 0, changing the relay log info repository type to
TABLE and restarting the slave
mysqld caused a subsequent
START SLAVE statement to crash
References: See also Bug #13804728, Bug #14550905, Bug #14578740.
A manually created file named
slave_worker_info in the MySQL
Server's data directory could be mistaken for the actual
relay log info file. In addition, when the number of workers
system variable) was decreased, the corresponding info files
were not removed as expected.
References: See also Bug #13804728, Bug #14550905, Bug #14550945.
function without binary logging enabled could cause the server
COM_BINLOG_DUMP_GTID with incorrect
data could cause the server to crash.
Replication: An internal routine in the MySQL Replication code removed elements from a hash used to store a mapping between databases and worker threads at the same time that the hash was being iterated over. This could cause an unintended reordering of the has elements and thus possibly to incorrect results from routines using this hash. (Bug #14381701)
References: See also Bug #13864642.
Replication: The names of the binary log and relay log Performance Schema mutexes were mistakenly changed to names that differed from the MySQL 5.5 names. The names have been reverted to those used in MySQL 5.5. (Bug #14366314)
When setting up replication between a master and a slave which
mysql.slave_master_info table was not
updated the first time that
SLAVE was issued.
References: See also Bug #13858841.
option caused any nontransactional DML statement involving
temporary tables to be rejected with an error even with
binlog_format set explicitly to
ROW, in spite of the fact that they are not
written to the binary log in this case. Now, such statements are
allowed when using row-based logging, as long as any
nontransactional tables affected by the statements are also
When using multi-threaded slaves,
--replicate-rewrite-db rules were
not honored while assigning databases to slave worker threads,
which could cause statements to be executed out of order when
this option was used. This could result in a slave that was
inconsistent with the master.
mysql_upgrade failed when the server was
because the MySQL system tables are stored using
MyISAM. This problem is fixed by
changing the default logging behavior for
mysql_upgrade; logging is now disabled by
default. (Actions taken by mysql_upgrade
depend on the server version, and thus should not be replicated
to slaves.) To enable logging, you can execute
mysql_upgrade using the
(Bug #14221043, Bug #13833710)
The initialization and usage of a number of internal programming
objects relating to GTIDs did not work properly with
Replication: The scheduler for multi-threaded slaves did not take into account databases implicitly involved in operations through foreign key dependencies, which could lead to a temporary loss of consistency on the slave. To avoid this problem, replication events on the master that invoke foreign key relationships between table is different databases are now marked in such a way that they can be scheduled sequentially to avoid race conditions and thereby inconsistency. However, this can adversely affect performance. (Bug #14092635)
Replication: When using a multi-threaded slave, the repository type employed for the relay log info log was not always used automatically for worker repositories as expected. (Bug #13804728)
References: See also Bug #14550905, Bug #14550945, Bug #14578740.
Replication: It was possible for the multi-threaded slave coordinator to leak memory when the slave was stopped while waiting for the next successful job to be added to the worker queue. (Bug #13635612)
Master_id column of the
mysql.slave_relay_log_info tables showed the
slave's server ID instead of the master's server ID.
Statements such as
UPDATE ... WHERE
flagged as unsafe for statement-based logging, despite the fact
that such statements are actually safe. In cases where a great
many such statements were run, this could lead to disk space
becoming exhausted do to the number of such false warnings being
logged. To prevent this from happening, a warning suppression
mechanism is introduced. This warning suppression acts as
follows: Whenever the 50 most recent
constant LIMIT 1
warnings have been generated more than 50 times in any 50-second
period, warning suppression is enabled. When activated, this
causes such warnings not to be written to the error log;
instead, for each 50 warnings of this type, a note is written to
the error log stating
The last warning was repeated
. This continues
as long as the 50 most recent such warnings were issued in 50
seconds or less; once the number of warnings has decreased below
this threshold, the warnings are once again logged normally.
N times in last
The fix for this issue does not affect how these warnings are reported to MySQL clients; a warning is still sent to the client for each statement that generates the warning. This fix also does not make any changes in how the safety of any statement for statement-based logging is determined. (Bug #11759333, Bug #51638)
References: See also Bug #11751521, Bug #42415.
ALTER TABLE ...
DROP FOREIGN KEY that did not name the foreign key to
be dropped caused a server crash. Now the foreign key name is
incorrectly were defined as the same value.
With a password policy of
STRONG and a
password of 100 characters or more,
could cause a server crash.
Polygons with holes could cause a server crash for spatial operations. (Bug #14497827)
variable was not updated properly.
mysql_secure_installation did not work if
old_passwords was set to 2 (use
sha256_password authentication plugin).
ORDER BY on
GEOMETRY values caused a server crash.
For complex conditions, the optimizer could produce an incorrect range construction and return incorrect query results. (Bug #14497598)
a null pointer if the cached value was
The optimizer could raise an assertion when grouping and sorting in descending order on an indexed column. (Bug #14498999)
A query with
GROUP BY ... WITH ROLLUP
comparing a grouping column using the
operator caused an assertion to be raised.
In debug builds, with semi-join enabled,
GROUP BY ...
WITH ROLLUP that did not use a temporary table could
cause a server crash.
An assertion was raised when using the join cache for a query
that contained an
IN subquery query with a
subquery that is expected to return a single row but returned
more than one.
Index condition pushdown in conjunction with descending index range scan caused a performance regression. (Bug #14503142)
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
--server-public-key option for
been renamed to
reflect that it refers to a file and for consistency with
related server-side variable naming. Also, this option now is
available only if MySQL was built with OpenSSL (not yaSSL)
because yaSSL does not support the necessary RSA encryption.
The result set could contain extra rows for queries on
MyISAM tables that used the
SQL_BUFFER_RESULT modifier and a subquery.
For debug builds, if one session used a DDL statement to alter
InnoDB table, another session could raise
an assertion failure if it had a pre-alter consistent snapshot
of the table.
The Performance Schema used listed the nanosecond timer by
default for stages and statements in the
setup_timers table. But if this
timer was not available on a given platform (such as Windows),
timing for stages and statements failed to work. Now the idle,
stage, and statement timers used the preferred timers if they
are available, but alternate timers if not.
The Performance Schema generated different digests for a statement before and after selecting a database. (Bug #14256311)
The RPM spec file now also runs the test suite on the new binaries, before packaging them. (Bug #14318456)
Inside a stored program, references to stored program variables
in XML functions such as
ExtractValue() failed after the
first execution of the stored program.
A LooseScan semi-join could return duplicate rows from the outer table. (Bug #14271594)
Some queries for which the optimizer used index condition
pushdown in conjunction with
ref access could be very slow
if the index was read in descending order.
(Bug #14287654, Bug #14503142)
Queries executed using MaterializeScan semi-join strategy and a materialized subquery could return too many rows. (Bug #14272788)
The server did not build with gcc 4.7. (Bug #14238406)
If a call to
socket() failed, the Performance
Schema created instrumentation for it anyway.
REQUIRE ISSUER clauses for
GRANT statements were not
rewritten properly for logging and caused a server crash.
For queries that used range access, the optimizer could read uninitialized data, resulting in Valgrind warnings. (Bug #14200538)
The Performance Schema digest-generation code could fail with a race condition. (Bug #14250296)
With semi-join optimization enabled, subqueries in the
WITH CHECK OPTION clause of view definitions
were evaluated incorrectly.
WEIGHT_STRING() could crash if
given a bad flags argument.
An optimizer trace could crash attempting to print freed subquery items. (Bug #14238404)
mysql_upgrade did not set the
STATS_PERSISTENT=0 table option for
InnoDB tables in the
ALTER TABLE with
IMPORT TABLESPACE did
not acquire a sufficiently strong metadata lock to prevent a
ALTER TABLE statement
modifying the tablespace. This could result in warnings or raise
Some queries with a
HAVING clause with a
function that referred to a function in the
WHERE list with a subquery as parameter
caused an assertion to be raised.
String allocation could cause Valgrind warnings. (Bug #14201818)
statements, derived tables were not handled properly and caused
a server crash.
Incorrect internal conversion of string-format dates could cause a server crash. (Bug #14167911)
In debug builds, comparisons for strings that had the
ucs2_unicode_520_ci collation could raise an
Join processing could attempt to clean up a temporary table that had not been instantiated, causing a server crash. (Bug #14168270)
In debug builds, the optimizer raised an unnecessary (too
strict) assertion about
ALTER TABLE did not work
for a table with a
GEOMETRY column, even if
the alteration did not involve that column.
Negative values could be erroneously reported for some columns
buffer_pool_pages_in_flush row in the
SAVEPOINT did not have sufficient checks for the XA
transaction state to prevent a savepoint from being released
while the transaction was in a prepared state.
The FirstMatch strategy for semi-joins produced incorrect results for some queries with multiple inner tables. (Bug #14081638)
With materialization and semi-joins enabled, some queries with an OR condition could produce incorrect results. (Bug #14075016)
ALTER TABLE did not
handle autopartitioning storage engines such as
EXPLAIN statements could raise an
assertion or cause the server to hang for statements with an
WHERE clause and subqueries in
ORDER BY or
For nonexistent files, the Performance Schema file I/O instrumentation sometimes did extra work or was subject to instrumentation leaks. (Bug #14113704)
Within a trigger, references to a temporary table used during the query execution process could end up pointing to nonexisting fields on subsequent executions, causing a server crash. (Bug #14105951)
could result in a server crash.
Improper initialization by spatial functions could cause a server crash the first time they were invoked following server startup. (Bug #14015762)
Polygon sorting by spatial functions could be done incorrectly and cause a server crash. (Bug #13938850)
statements, improper handling of subqueries could cause an
assertion to be raised.
SELECT on a partitioned table
that used a join buffer could cause a server crash.
The argument for
LIMIT must be an integer,
but if the argument was given by a placeholder in a prepared
statement, the server did not reject noninteger values such as
WHERE clause row retrieval that should access
only the index tree could raise an assertion.
Some arguments could cause
(Bug #13832749, Bug #13833019)
The optimizer used a full index scan for cases for which a loose index scan was preferable. (Bug #13464493)
References: This bug is a regression of Bug #12540545.
COUNT(DISTINCT(SELECT 1)) could be evaluated
incorrectly if the optimizer used Loose Index Scan.
References: See also Bug #13813126.
A query for a
FEDERATED table could
return incorrect results when the underlying table had a
compound index on two columns and the query included an
AND condition on the columns.
mysqlhotcopy failed for databases containing views. (Bug #62472, Bug #13006947, Bug #12992993)
“Illegal mix of collation” errors were returned for some operations between strings that should have been legal. (Bug #64555, Bug #13812875)
mysqldump could dump views and the tables on which they depend in such an order that errors occurred when the dump file was reloaded. (Bug #44939, Bug #11753490)
LIMIT clause to a query containing
GROUP BY and
could cause the optimizer to choose an incorrect index for
processing the query, and return more rows than required.
(Bug #54599, Bug #11762052)
If the server was started with
secure_auth disabled, it did
not produce a warning that this is a deprecated setting.
(Bug #65462, Bug #14136937)
GeomFromWKB() function did
NULL if the SRID argument was
NULL, and non-
values were not included in the converted result.
(Bug #65094, Bug #13998446)
With statement-based binary logging, stored routines that accessed but did not modify tables took too strong a lock for the tables, unnecessarily blocking other statements that also accessed those tables. (Bug #62540, Bug #13036505)
In prepared statements,
parameters when converted to an integer were handled as
MYSQL_TYPE_DATETIME values and the conversion
produced incorrect results.
(Bug #64667, Bug #13904869)
mysqlbinlog did not accept input on the standard input when the standard input was a pipe. (Bug #49336, Bug #11757312)
The argument to the
option was not verified to exist and be a valid key. The
resulting connection used SSL, but the key was not used.
(Bug #62743, Bug #13115401)
ALTER TABLE incorrectly
handled indexes using key prefixes by using a copy algorithm.
(Bug #65865, Bug #14304973)
COUNT(DISTINCT(IF ...)) could be evaluated
incorrectly if the optimizer used Loose Index Scan.
(Bug #64445, Bug #13813126)
References: See also Bug #13444084.
Starting the server with
supposed to cause the server to accept TCP/IP connections on all
server host IPv6 and IPv4 interfaces if the server host supports
IPv6, or TCP/IP connections on all IPv4 addresses otherwise. But
the server sometimes did not correctly detect when IPv6 was not
supported, and failed to start.
(Bug #66303, Bug #14483430)
were unnecessarily registered in an open-table list protected by
a global mutex, causing excessive mutex contention.
(Bug #65077, Bug #14000697)
ALL over a
UNION could return an incorrect result if the
UNION result contained
(Bug #65902, Bug #14329235)
There was a performance regression for queries that used
GROUP BY and
(Bug #49111, Bug #11757108)
In debug builds, an
assertion was overly aggressive about prohibiting an open range.
(Bug #66513, Bug #14547952)