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.
InnoDB: A new
INNODB_METRICS, lets you query low-level
InnoDBperformance information, getting cumulative counts, averages, and minimum/maximum values for internal aspects of the storage engine operation. You can start, stop, and reset the metrics counters using the
InnoDBdata dictionary, containing metadata about
InnoDBtables, columns, indexes, and foreign keys, is available for SQL queries through a set of
Performance; InnoDB: The optimizer statistics for
InnoDBtables can now persist across server restarts, producing more stable query performance. You can also control the amount of sampling done to estimate cardinality for each index, resulting in more accurate optimizer statistics. This feature involves the configuration options
innodb_analyze_is_persistent(later replaced by
innodb_stats_transient_sample_pages, and the
ANALYZE TABLEstatement. See Configuring Persistent Optimizer Statistics Parameters for details.
InnoDB: To ease the memory load on systems with huge numbers of tables,
InnoDBnow frees up the memory associated with an opened table using an LRU algorithm to select tables that have gone the longest without being accessed. To reserve more memory to hold metadata for open
InnoDBtables, increase the value of the
InnoDBtreats this value as a “soft limit” for the number of open table instances in the
InnoDBdata dictionary cache. The actual number of tables with cached metadata could be higher than the value specified for
table_definition_cache, because metadata for
InnoDBsystem tables, and parent and child tables in foreign key relationships, is never evicted from memory. For additional information, refer to the
table_definition_cachedocumentation. (Bug #20877, Bug #11745884)
The optimizer now more efficiently handles queries (and subqueries) of the following form:
SELECT ... FROM
single_table... ORDER BY
non_index_column[DESC] LIMIT [
That type of query is common in web applications that display only a few rows from a larger result set. For example:
SELECT col1, ... FROM t1 ... ORDER BY name LIMIT 10; SELECT col1, ... FROM t1 ... ORDER BY RAND() LIMIT 15;
The sort buffer has a size of
sort_buffer_size. If the sort elements for
Nrows are small enough to fit in the sort buffer (
Mwas specified), the server can avoid using a merge file and perform the sort entirely in memory. For details, see LIMIT Query Optimization.
The optimizer implements Disk-Sweep Multi-Range Read. Reading rows using a range scan on a secondary index can result in many random disk accesses to the base table when the table is large and not stored in the storage engine's cache. With the Disk-Sweep Multi-Range Read (MRR) optimization, MySQL tries to reduce the number of random disk access for range scans by first scanning the index only and collecting the keys for the relevant rows. Then the keys are sorted and finally the rows are retrieved from the base table using the order of the primary key. The motivation for Disk-sweep MRR is to reduce the number of random disk accesses and instead achieve a more sequential scan of the base table data. For more information, see Multi-Range Read Optimization.
The optimizer implements Index Condition Pushdown (ICP), an optimization for the case where MySQL retrieves rows from a table using an index. Without ICP, the storage engine traverses the index to locate rows in the base table and returns them to the MySQL server which evaluates the
WHEREcondition for the rows. With ICP enabled, and if parts of the
WHEREcondition can be evaluated by using only fields from the index, the MySQL server pushes this part of the
WHEREcondition down to the storage engine. The storage engine then evaluates the pushed index condition by using the index entry and only if this is satisfied is base row be read. ICP can reduce the number of accesses the storage engine has to do against the base table and the number of accesses the MySQL server has to do against the storage engine. For more information, see Index Condition Pushdown Optimization.
Partitioning: It is now possible to select one or more partitions or subpartitions when querying a partitioned table. In addition, many data modification statements (
LOAD DATA, and
LOAD XML) that act on partitioned tables also now support explicit partition selection. For example, assume we have a table named
twith some integer column named
thas 4 partitions named
p3. Then the query
SELECT * FROM t PARTITION (p0, p1) WHERE c < 5returns rows only in partitions
p1that match the
WHEREcondition, whereas partitions
p3are not checked.
For additional information and examples, see Partition Selection, as well as the descriptions of the statements just listed.
The Performance Schema has these additions:
The Performance Schema now has tables that contain summaries for table and index I/O wait events, as generated by the
The information in these tables can be used to assess the impact of table I/O performed by applications. For example, it is possible to see which tables are used and which indexes are used (or not used), or to identify bottlenecks on a table when multiple applications access it. The results may be useful to change how applications issue queries against a database, to minimize application footprint on the server and to improve application performance and scalability.
A change that accompanies the new tables is that the
events_waits_currenttable now has an
INDEX_NAMEcolumn to identify which index was used for the operation that generated the event. The same is true of the event-history tables,
The Performance Schema now has an instrument named
setup_instrumentstable for instrumenting table lock wait events. It differs from
wait/io/table/sql/handler, which instruments table I/O. This enables independent instrumentation of table I/O and table locks.
Accompanying the new instrument, the Performance Schema has a table named
table_lock_waits_summary_by_tablethat aggregates table lock wait events, as generated by the new instrument. The grouping is by table.
The information in this table may be used to assess the impact of table locking performed by applications. The results may be useful to change how applications issue queries against the database and use table locks, to minimize the application footprint on the server and to improve application performance and scalability. For example, an application locking tables for a long time may negatively affect other applications; the instrumentation makes this visible.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and restart the server) to incorporate these changes into the
For more information, see MySQL Performance Schema.
MySQL distributions now include
auth_socket, a server-side authentication plugin that authenticates clients that connect from the local host through the Unix socket file. The plugin uses the
SO_PEERCREDsocket option to obtain information about the user running the client program (and thus can be built only on systems that support this option). For a connection to succeed, the plugin requires a match between the login name of the connecting client user and the MySQL user name presented by the client program. For more information, see The Socket Peer-Credential Authentication Plugin. (Bug #59017, Bug #11765993, Bug #9411, Bug #11745104)
MySQL distributions now include
mysql_clear_password, a client-side authentication plugin that sends the password to the server without hashing or encryption. Although this is insecure, and thus appropriate precautions should be taken (such as using an SSL connection), the plugin is useful in conjunction with server-side plugins that must have access to the original password in clear text. For more information, see The Cleartext Client-Side Authentication Plugin.
Replication: Support for checksums when writing and reading the binary log is added to the MySQL Server. Writing checksums into the binary log is disabled by default; it can be enabled by starting the server with the
--binlog-checksumoption. To cause the server to read checksums from the binary log, start the server with the
--slave-sql-verify-checksumoption causes the slave to read checksums from the relay log.
Replication: The MySQL Server now records and reads back only complete events or transactions to and from the binary log. By default, the server now logs the length of the event as well as the event itself and uses this information to verify that the event was written correctly to the log. A master also uses by default this value to verify events when reading from the binary log.
If you enable writing of checksums (using the
binlog_checksumsystem variable), the master can use these instead by enabling the
master_verify_checksumsystem variable. The slave I/O thread also verifies events received from the master. You can cause the slave SQL thread to use checksums (if available) as well, when reading from the relay log, by enabling the
slave_sql_verify_checksumsystem variable on the slave.
Replication: It is now possible to write information about the slave connection to the master and about the slave's execution point within the relay log to tables rather than files. Logging of master connection information and of slave relay log information to tables can be done independently of one another; this is controlled by the
--relay-log-info-repositoryserver options. When
--master-info-repositoryis set to
TABLE, connection information is logged in the
slave_master_infotable in the
mysqlsystem database. When
--relay-log-info-repositoryis set to
TABLE, relay log information is logged to the
slave_relay_log_infotable, also in the
Replication: Added the
binlog_row_imageserver system variable, which can be used to enable row image control for row-based replication. This means that you can potentially save disk space, network resources, and memory usage by the MySQL Server by logging only those columns that are required for uniquely identifying rows, or which are actually changed on each row, as opposed to logging all columns for each and every row change event. In addition, you can use a “noblob” mode where all columns, except for unneeded
TEXTcolumns, are logged.
For more information, see System Variables Used with Binary Logging. (Bug #47200, Bug #47303, Bug #56917, Bug #11755426, Bug #11755513, Bug #11764116)
Performance; InnoDB: A separate
page_cleaner) now handles the flushing of dirty pages that was formerly done by the
InnoDBmaster thread. (Bug #11762412, Bug #55004)
Performance; InnoDB: The
innodb_purge_threadssystem variable can now be set to a value higher than 1.
Incompatible Change: The following obsolete constructs have been removed. Where alternatives are shown, applications should be updated to use them.
Important Change; Replication: Added the
--binlog-rows-query-log-eventsoption for mysqld. Using this option causes a server logging in row-based mode to write informational rows query log events (SQL statements, for debugging and other purposes) to the binary log. MySQL server and MySQL programs from MySQL 5.6.2 and later normally ignore such events, so that they do not pose an issue when reading the binary log. mysqld and mysqlbinlog from previous MySQL releases cannot read such events in the binary log, and fail if they attempt to do so. For this reason, you should never prepare logs for a MySQL 5.6.1 or earlier replication slave server (or other reader such as mysqlbinlog) with this option enabled on the master. (Bug #50935, Bug #11758695)
InnoDBcan optionally log details about all deadlocks that occur, to assist with troubleshooting and diagnosis. This feature is controlled by the
innodb_print_all_deadlockssystem variable. (Bug #1784, Bug #17572)
Replication: On MySQL replication slaves having multiple network interfaces, it is now possible to set which interface to use for connecting to the master using the
MASTER_BIND='option in a
CHANGE MASTER TOstatement.
The value set by this option can be seen in the
Master_Bindcolumn of the output from
SHOW SLAVE STATUSor the
Bindcolumn of the
mysql.slave_master_infotable. (Bug #25939, Bug #11746389)
Replication: Added the
log_bin_basenamesystem variable, which contains the complete file name and path to the binary log file. (The
log_binsystem variable shows only whether or not binary logging is enabled;
log_bin_basename, however, reflects the name set with the
--log-binserver option.) Also added
relay_log_basenamesystem variable, which shows the file name and complete path to the relay log file.
References: See also: Bug #19614, Bug #11745759.
The mysql_upgrade, mysqlbinlog, mysqlcheck, mysqlimport, mysqlshow, and mysqlslap clients now have
--plugin-diroptions for specifying which authentication plugin and plugin directory to use. (Bug #58139)
The server now includes the thread ID in rows written to the slow query log. In the slow query log file, the thread ID is the last value in the line. In the
mysql.slow_loglog table, there is a new
To update the
slow_logtable if you are upgrading from an earlier release, run mysql_upgrade and restart the server. See mysql_upgrade — Check and Upgrade MySQL Tables. (Bug #53630, Bug #11761166)
The server now writes thread shutdown messages to the error log during the shutdown procedure. (Bug #48388, Bug #11756464)
--init-fileoption is given, the server now writes messages indicating the beginning and end of file execution to the error log. (Bug #48387, Bug #11756463)
Boolean system variables can be enabled at run time by setting them to the value
OFF, but previously this did not work at server startup. Now at startup such variables can be enabled by setting them to
TRUE, or disabled by setting them to
FALSE. Any other nonnumeric value is invalid. (Bug #46393)
References: See also: Bug #11754743, Bug #51631.
MySQL distributions now include an
INFO_SRCfile that contains information about the source distribution, such as the MySQL version from which it was created. MySQL binary distributions additionally include an
INFO_BINfile that contains information about how the distribution was built, such as compiler options and feature flags. In RPM packages, these files are located in the
tar.gzand derived packages, they are located in the
Docsdirectory under the location where the distribution is unpacked. (Bug #42969, Bug #11751935)
Multi-read range access is now based on cost estimates and no longer used for simple queries for which it is not beneficial. (Bug #37576, Bug #11748865)
Previously, for queries that were aborted due to a sort problem, the server wrote the message
Sort abortedto the error log. Now the server writes more information to provide a more specific message, such as:
Sort aborted: Out of memory (Needed 24 bytes) Out of sort memory, consider increasing server sort buffer size Sort aborted: Out of sort memory, consider increasing server sort buffer size Sort aborted: Incorrect number of arguments for FUNCTION test.f1; expected 0, got 1
In addition, if the server was started with
--log-warnings=2, the server writes information about the host, user, and query. (Bug #36022, Bug #11748358)
Previously, for queries that were aborted due to a sort problem or terminated with
KILLin the middle of a sort, the server wrote the message
Sort abortedto the error log. Now the server writes more information about the cause of the error. These causes include:
Insufficient disk space in the temporary file directory prevented a temp file from being created
Insufficient memory for
sort_buffer_sizeto be allocated
KILLin the middle of a filesort operation
The server was shut down while some queries were sorting
A transaction was rolled back or aborted due to a lock wait timeout or deadlock
Unexpected errors, such as a source table or even temp table was corrupt
Processing of a subquery failed which was also sorting
(Bug #30771, Bug #11747102)
mysqldump --xml now displays comments from column definitions. (Bug #13618, Bug #11745324)
Windows provides APIs based on UTF-16LE for reading from and writing to the console. MySQL now supports a
utf16lecharacter set for UTF-16LE, and the mysql client for Windows has been modified to provide improved Unicode support by using these APIs.
To take advantage of this change, you must run mysql within a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server. For instructions, see Unicode Support on Windows.
SHOW NEW MASTERstatement has been removed.
A new plugin service,
my_plugin_log_service, enables plugins to report errors and specify error messages. The server writes the messages to the error log. See MySQL Services for Plugins.
Security Fix: Pre-evaluation of
LIKEpredicates during view preparation could cause a server crash. (Bug #54568, Bug #11762026, CVE-2010-3836)
Performance; InnoDB: An
UPDATEstatement for an
InnoDBtable could be slower than necessary if it changed a column covered by a prefix index, but did not change the prefix portion of the value. The fix improves performance for InnoDB 1.1 in MySQL 5.5 and higher, and the InnoDB Plugin for MySQL 5.1. (Bug #58912, Bug #11765900)
Incompatible Change; Replication: It is no longer possible to issue a
CREATE TABLE ... SELECTstatement which changes any tables other than the table being created. Any such statement is not executed and instead fails with an error.
This means that, prior to upgrading from a previous release, you should rewrite any
CREATE TABLE ... SELECTstatements that cause changes in other tables so that the statements no longer do so.
This change also has implications for statement-based replication between a MySQL 5.6 (or later slave) and a master running a previous version of MySQL. In such a case, if a
CREATE TABLE ... SELECTstatement on the master that causes changes in other tables succeeds on the master, the statement nonetheless fails on the slave, causing replication to stop. To keep this from happening, you should either use row-based replication, or rewrite the offending statement before running it on the master. (Bug #11749792, Bug #11745361, Bug #39804, Bug #55876)
References: See also: Bug #47899.
Incompatible Change: When
auto_increment_incrementis greater than one, values generated by a bulk insert that reaches the maximum column value could wrap around rather producing an overflow error.
As a consequence of the fix, it is no longer possible for an auto-generated value to be equal to the maximum
BIGINT UNSIGNEDvalue. It is still possible to store that value manually, if the column can accept it. (Bug #39828, Bug #11749800)
Important Change; Partitioning: Date and time functions used as partitioning functions now have the types of their operands checked; use of a value of the wrong type is now disallowed in such cases. In addition,
EXTRACT(WEEK FROM, where
DATETIMEcolumn, is now disallowed altogether because its return value depends on the value of the
default_week_formatsystem variable. (Bug #54483, Bug #11761948)
References: See also: Bug #57071, Bug #11764255.
Important Change; Replication: The
CHANGE MASTER TOstatement required the value for
RELAY_LOG_FILEto be an absolute path, whereas the
MASTER_LOG_FILEpath could be relative.
The inconsistent behavior is resolved by permitting relative paths for
RELAY_LOG_FILE, in which case the path is assumed to be relative to the slave's data directory. (Bug #12190, Bug #11745232)
InnoDB; Partitioning: The partitioning handler did not pass locking information to a table's storage engine handler. This caused high contention and thus slower performance when working with partitioned
InnoDBtables. (Bug #59013)
InnoDB: This fix introduces a new configuration option,
innodb_change_buffer_max_size, which defines the size of the change buffer as a percentage of the size of the buffer pool. Because the change buffer shares memory space with the buffer pool, a workload with a high rate of DML operations could cause pages accessed by queries to age out of the buffer pool sooner than desirable. This fix also devotes more I/O capacity to flushing entries from the change buffer when it exceeds 1/2 of its maximum size. (Bug #11766168, Bug #59214)
InnoDB: The presence of a double quotation mark inside the
COMMENTfield for a column could prevent a foreign key constraint from being created properly. (Bug #59197, Bug #11766154)
InnoDBreturned values for “rows examined” in the query plan that were higher than expected.
NULLvalues were treated in an inconsistent way. The inaccurate statistics could trigger “false positives” in combination with the
max_join_sizesetting, because the queries did not really examine as many rows as reported.
A new configuration option
innodb_stats_methodlets you specify how
NULLvalues are treated when calculating index statistics. Allowed values are
null_ignored. The meanings of these values are similar to those of the
myisam_stats_methodoption. (Bug #30423)
ALTER TABLE ... PARTITIONstatements could cause memory leaks. (Bug #56380, Bug #11763641)
References: See also: Bug #46949, Bug #11755209, Bug #56996, Bug #11764187.
Replication: When using the statement-based logging format,
INSERT ON DUPLICATE KEY UPDATEand
INSERT IGNOREstatements affecting transactional tables that did not fail were not written to the binary log if they did not insert any rows. (With statement-based logging, all successful statements should be logged, whether they do or do not cause any rows to be changed.) (Bug #59338, Bug #11766266)
STOP SLAVEstopped the slave I/O thread first and then stopped the slave SQL thread; thus, it was possible for the I/O thread to stop after replicating only part of a transaction which the SQL thread was executing, in which case—if the transaction could not be rolled back safely—the SQL thread could hang.
STOP SLAVEstops the slave SQL thread first and then stops the I/O thread; this guarantees that the I/O thread can fetch any remaining events in the transaction that the SQL thread is executing, so that the SQL thread can finish the transaction if it cannot be rolled back safely. (Bug #58546, Bug #11765563)
Replication: mysqlbinlog printed
USEstatements to its output only when the default database changed between events. To illustrate how this could cause problems, suppose that a user issued the following sequence of statements:
CREATE DATABASE mydb; USE mydb; CREATE TABLE mytable (
column_definitions); DROP DATABASE mydb; CREATE DATABASE mydb; USE mydb; CREATE TABLE mytable (
When played back using mysqlbinlog, the second
CREATE TABLEstatement failed with Error: No Database Selected because the second
USEstatement was not played back, due to the fact that a database other than
mydbwas never selected.
This fix ensures that mysqlbinlog outputs a
USEstatement whenever it reads one from the binary log. (Bug #50914, Bug #11758677)
--helptext for mysqlbinlog now indicates that the
-v) option outputs pseudo-SQL that is not necessarily valid SQL and cannot be guaranteed to work verbatim in MySQL clients. (Bug #47557, Bug #11755743)
Two unused test files in
storage/ndb/test/sqlcontained incorrect versions of the GNU Lesser General Public License. The files and the directory containing them have been removed. (Bug #11810224)
References: See also: Bug #11810156.
Queries that used
cp1251strings could result in an “illegal mix of collations” error. (Bug #60101, Bug #11766874)
An assertion was raised if an
XA COMMITwas issued when an XA transaction had already encountered an error (such as a deadlock) that required the transaction to be rolled back. (Bug #59986, Bug #11766788)
On some systems, debug builds of
comp_errcould fail due to an uninitialized variable. (Bug #59906, Bug #11766729)
optimizer_switchsystem variable to an invalid value caused a server crash. (Bug #59894, Bug #11766719)
Attempting to create a spatial index on a
CHARcolumn longer than 31 bytes led to an assertion failure if the server was compiled with safemutex support. (Bug #59888, Bug #11766714)
Aggregation followed by a subquery could produce an incorrect result. (Bug #59839, Bug #11766675)
The Performance Schema did not update status handler status variables, so
SHOW STATUS LIKE '%handler%'produced undercounted values. (Bug #59799, Bug #11766645)
Internally, XOR items partially behaved like functions and partially as conditions. This resulted in inconsistent handling and crashes. The issue is fixed by consistently treating XOR items as functions. (Bug #59793, Bug #11766642)
An incorrect character set pointer passed to
my_strtoll10_mb2()caused an assertion to be raised. (Bug #59648, Bug #11766519)
The server and client did not always properly negotiate authentication plugin names. (Bug #59453, Bug #11766356)
FIND_IN_SET()could work differently in MySQL 5.5 than in 5.1. (Bug #59405, Bug #11766317)
mysqldump did not quote database names in
ALTER DATABASEstatements in its output, which could cause an error at reload time for database names containing a dash. (Bug #59398, Bug #11766310)
filesortfell back to an ordinary sort/merge, it could fail to handle memory correctly. (Bug #59331, Bug #11766260)
Comparisons of aggregate values with
TIMESTAMPvalues were incorrect. (Bug #59330, Bug #11766259)
The “greedy” query plan optimizer failed to consider the size of intermediate query results when calculating the cost of a query. This could result in slowly executing queries when there are much faster execution plans available. (Bug #59326, Bug #11766256)
A query of the following form returned an incorrect result, where the values for
col_namein the result set were entirely replaced with
col_name... ORDER BY
(Bug #59308, Bug #11766241)
MYSQL_HOMEenvironment variable was being ignored. (Bug #59280, Bug #11766219)
SHOW PROFILEcould truncate source file names or fail to show function names. (Bug #59273, Bug #11766214)
DIVexpressions, assignment of the result to multiple variables could cause a server crash. (Bug #59241, Bug #11766191)
References: See also: Bug #8457.
MIN(could return an incorrect result in some cases. (Bug #59211, Bug #11766165)
With index condition pushdown enabled, a join could produce an extra row due to parts of the select condition for the second table in the join not being evaluated. (Bug #59186, Bug #11766144)
ESCAPEclause for the
LIKEoperator permits only expressions that evaluate to a constant at execution time, but aggregate functions were not being rejected. (Bug #59149, Bug #11766110)
Valgrind warnings about uninitialized variables were corrected. (Bug #59145, Bug #11766106)
Memory leaks detected by Valgrind, some of which could cause incorrect query results, were corrected. (Bug #59110, Bug #11766075)
mysqlslap failed to check for a
mysql_store_result()and crashed trying to process the result set. (Bug #59109, Bug #11766074)
There was an erroneous restriction on file attributes for
LOAD DATA INFILE. The requirement that a file be located in the database directory or world readable is now that the be located in the database directory or readable by the user account used to run the server. (Bug #59085, Bug #11766052)
SHOW CREATE TRIGGERfailed if there was a temporary table with the same name as the trigger subject table. (Bug #58996, Bug #11765972)
In a subquery, a
UNIONwith no referenced tables (or only a reference to the
DUALvirtual table) did not permit an
ORDER BYclause. (Bug #58970, Bug #11765950)
max_allowed_packetwas set larger than 16MB, the server failed to reject too-large packets with “Packet too large” errors. (Bug #58887, Bug #11765878)
With index condition pushdown enabled, incorrect results were returned for queries on
LIMIT, when the column in the
NULL. (Bug #58838, Bug #11765835)
An uninitialized variable for the index condition pushdown access method could result in a server crash or Valgrind warnings. (Bug #58837, Bug #11765834)
NOT INpredicate with a subquery containing a
HAVINGclause could retrieve too many rows, when the subquery itself returned
NULL. (Bug #58818, Bug #11765815)
Running a query against an
InnoDBtable twice, first with index condition pushdown enabled and then with it disabled, could produce different results. (Bug #58816, Bug #11765813)
An assertion was raised if a stored routine had a
DELETE IGNOREstatement that failed but due to the
IGNOREhad not reported any error. (Bug #58709, Bug #11765717)
WHEREconditions of the following forms were evaluated incorrectly and could return incorrect results:
null-valued-const-expressionNOT IN (
subquery) IS UNKNOWN
(Bug #58628, Bug #11765642)
EXPLAIN EXTENDEDfor a query that would use condition pushdown could cause mysqld to crash. (Bug #58553, Bug #11765570)
OUTER JOINquery using
WHEREcould return an incorrect result. (Bug #58490, Bug #11765513)
Starting the server with the
--defaults-file=option, where the file name had no extension, caused a server crash. (Bug #58455, Bug #11765482)
Outer joins with an empty table could produce incorrect results. (Bug #58422, Bug #11765451)
In debug builds,
SUBSTRING_INDEX(FORMAT(...), FORMAT(...))could cause a server crash. (Bug #58371, Bug #11765406)
Some string-manipulating SQL functions use a shared string object intended to contain an immutable empty string. This object was used by the SQL function
SUBSTRING_INDEX()to return an empty string when one argument was of the wrong data type. If the string object was then modified by the SQL function
INSERT(), undefined behavior ensued. (Bug #58165, Bug #11765225)
Condition pushdown optimization could push down conditions with incorrect column references. (Bug #58134, Bug #11765196)
injector::transactiondid not have support for rollback. (Bug #58082, Bug #11765150)
Parsing nested regular expressions could lead to recursion resulting in a stack overflow crash. (Bug #58026, Bug #11765099)
The fix for Bug #25192 caused
load_defaults()to add an argument separator to distinguish options loaded from option files from those provided on the command line, whether or not the application needed it. (Bug #57953, Bug #11765041)
References: See also: Bug #25192, Bug #11746296.
The mysql client went into an infinite loop if the standard input was a directory. (Bug #57450, Bug #11764598)
If a multiple-table update updated a row through two aliases and the first update physically moved the row, the second update failed to locate the row. This resulted in different errors depending on the storage engine, although these errors did not accurately describe the problem:
MyISAM, which is nontransactional, the update executed first was performed but the second was not. In addition, for two equal multiple-table update statements, one could succeed and the other fail depending on whether the record actually moved, which is inconsistent.
Now such an update returns an error if it will update a table through multiple aliases, and perform an update that may physically move the row in at least one of these aliases. (Bug #57373, Bug #11764529, Bug #55385, Bug #11762751)
Outer joins on a unique key could return incorrect results. (Bug #57034, Bug #11764219)
For a query that used a subquery that included
GROUP BYinside a
< ANY()construct, no rows were returned when there should have been. (Bug #56690, Bug #11763918)
Some RPM installation scripts used a hardcoded value for the data directory, which could result in a failed installation for users who have a nonstandard data directory location. The same was true for other configuration values such as the PID file name. (Bug #56581, Bug #11763817)
On FreeBSD and OpenBSD, the server incorrectly checked the range of the system date, causing legal values to be rejected. (Bug #55755, Bug #11763089)
On Windows, an object in thread local storage could be used before the object was created. (Bug #55730, Bug #11763065)
If one connection locked the
mysql.functable using either
FLUSH TABLES WITH READ LOCKor
LOCK TABLE mysql.func WRITEand a second connection tried to either create or drop a UDF function, a deadlock occurred when the first connection tried to use a UDF function. (Bug #53322, Bug #11760878)
DECIMAL UNSIGNEDfields could trigger an assertion. (Bug #52171, Bug #11759827)
On FreeBSD, if mysqld was killed with a
SIGHUPsignal, it could corrupt
.ibdfiles. (Bug #51023, Bug #11758773)
An assertion could be raised if −1 was inserted into an
AUTO_INCREMENTcolumn by a statement writing more than one row. (Bug #50619, Bug #11758417)
A query that contains an aggregate function but no
GROUP BYclause is implicitly grouped. If such a query also contained an
ORDER BYclause, the optimizer could choose to use a temporary table to perform the ordering. This is unnecessary because implicitly grouped queries return at most one row and need no ordering. (Bug #47853)
The parser failed to initialize some internal objects properly, which could cause a server crash in the cleanup phase after statement execution. (Bug #47511, Bug #11755703)
CASE ... WHENarguments had different character sets, 8-bit values could be referenced as
utf32values, raising an assertion. (Bug #44793, Bug #11753363)
UpdateXML(), if the XML to be read contained an incomplete XML comment, MySQL read beyond the end of the XML string when processing, leading to a crash of the server. (Bug #44332, Bug #11752979)
Bitmap functions used in one thread could change bitmaps used by other threads, raising an assertion. (Bug #43152, Bug #11752069)
DATE_SUB()return a string if the first argument is a string, but incorrectly returned a binary string. Now they return a character string with a collation of
connection_collation. (Bug #31384, Bug #11747221)