This is a milestone release, for use at your own risk. Upgrades between milestone releases (or from a milestone release to a GA release) are not supported. 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. (Making a backup before the upgrade is a prudent precaution in any case.)
Replication: These unused and deprecated items have been removed: the
rpl_recovery_ranksystem variable, and the
Rpl_statusstatus variable. (Bug #54649, Bug #11762095)
References: See also: Bug #34437, Bug #11747900, Bug #34635, Bug #11747961.
In MySQL 5.5, setting
optimizer_search_depthto the deprecated value of 63 switched to the algorithm used in MySQL 5.0.0 (and previous versions) for performing searches. The value of 63 is now treated as invalid.
The Performance Schema now includes instrumentation for table input and output. Instrumented operations include row-level accesses to persistent base tables or temporary tables. Operations that affect rows are fetch, insert, update, and delete. For a view, waits are associated with base tables referenced by the view.
Replication: Globally unique IDs for MySQL servers were implemented. A UUID is now obtained automatically when the MySQL server starts. The server first checks for a UUID written in the
auto.cnffile (in the server's data directory), and uses this UUID if found. Otherwise, the server generates a new UUID and saves it to this file (and creates the file if it does not already exist). This UUID is available as the
MySQL replication masters and slaves know each other's UUIDs. The value of a slave's UUID can be read in the output of
SHOW SLAVE HOSTS. After a slave is started using
START SLAVE, the value of the master's UUID is available on the slave in the output of
SHOW SLAVE STATUS. (Bug #33815, Bug #11747723)
References: See also: Bug #16927, Bug #11745543.
Partitioning: It is now possible to exchange a partition of a partitioned table or a subpartition of a subpartitioned table with a nonpartitioned table that otherwise has the same structure using the
ALTER TABLE ... EXCHANGE PARTITIONstatement. This can be used, for example, for importing and exporting partitions.
For more information and examples, see Exchanging Partitions and Subpartitions with Tables.
SHOW SLAVE STATUSstatement now has a
Master_Info_Filefield indicating the location of the
master.infofile. (Bug #50316, Bug #11758151)
Replication: MySQL now supports delayed replication such that a slave server deliberately lags behind the master by at least a specified amount of time. The default delay is 0 seconds. Use the new
CHANGE MASTER TOto set the delay to
CHANGE MASTER TO MASTER_DELAY = N;
An event received from the master is not executed until at least
Nseconds later than its execution on the master.
SHOW SLAVE STATUShas three new fields that provide information about the delay:
SQL_Delay: The number of seconds that the slave must lag the master.
Waiting until MASTER_DELAY seconds after master executed event, this field contains the number of seconds left of the delay. At other times, this field is
Slave_SQL_Running_State: The state of the SQL thread (analogous to
Slave_IO_State). The value is identical to the
Statevalue of the SQL thread as displayed by
When the slave SQL thread is waiting for the delay to elapse before executing an event,
SHOW PROCESSLISTdisplays its
Waiting until MASTER_DELAY seconds after master executed event.
relay-log.infofile now contains the delay value, so the file format has changed. See Replication Metadata Repositories. In particular, the first line of the file now indicates how many lines are in the file. If you downgrade a slave server to a version older than MySQL 5.6, the older server will not read the file correctly. To address this, modify the file in a text editor to delete the initial line containing the number of lines.
The introduction of delayed replication entails these restrictions:
BINLOGstatement could execute all types of events. Now it can execute only format description events and row events.
The output from mysqlbinlog --base64-output=ALWAYS cannot be parsed.
ALWAYSbecomes an invalid value for this option in 5.6.1.
For additional information, see Delayed Replication. (Bug #28760, Bug #11746794)
The Romansh locale
'rm_CH'is now a permissible value for the
lc_time_namessystem variable. (Bug #50915, Bug #11758678)
mysqlbinlog now has a
--binlog-row-event-max-sizeoption to enable large row events to be read from binary log files. (Bug #49932)
Vietnamese collations were added for the Unicode character sets. Those based on Unicode Collation Algorithm 5.2.0 have names of the form
utf8_vietnamese_520_ci). Those based on Unicode Collation Algorithm 4.0.0 have names of the form
utf8_vietnamese_ci). These collations are the same as the corresponding
collations except for precomposed characters which are accented versions of “
O”, and “
U”. There is no change to ideographic characters derived from Chinese. There are no digraphs.
Unicode collation names now may include a version number to indicate the Unicode Collation Algorithm (UCA) version on which the collation is based. Initial collations thus created use version UCA 5.2.0. For example,
utf8_unicode_520_ciis based on UCA 5.2.0. UCA-based Unicode collation names that do not include a version number are based on version 4.0.0.
UPPER()perform case folding according to the collation of their argument. A character that has uppercase and lowercase versions only in a Unicode version more recent than 4.0.0 will be converted by these functions only if the argument has a collation that uses a recent enough UCA version.
The LDML rules for creating user-defined collations are extended to permit an optional
<collation>tags to indicate the UCA version on which the collation is based. If the
versionattribute is omitted, its default value is
4.0.0. See Adding a UCA Collation to a Unicode Character Set.
The Unicode character sets now have a
collation that provides DIN-2 (phone book) ordering (for example,
utf8_german2_ci). See Unicode Character Sets.
mysqlbinlog now has the capability to back up a binary log in its original binary format. When invoked with the
--rawoptions, mysqlbinlog connects to a server, requests the log files, and writes output files in the same format as the originals. See Using mysqlbinlog to Back Up Binary Log Files.
A new SQL function,
WEIGHT_STRING(), returns the weight string for an input string. The weight string represents the sorting and comparison value of the input string. See String Functions and Operators.
Security Fix: A security bug was fixed. (Bug #49124)
InnoDB: The server could crash on shutdown, if started with
--innodb-use-system-malloc=0. (Bug #55581, Bug #11762927)
Replication: The internal flag indicating whether a user value was signed or unsigned (
unsigned_flag) could sometimes change between the time that the user value was recorded for logging purposes and the time that the value was actually written to the binary log, which could lead to inconsistency. Now
unsigned_flagis copied when the user variable value is copied, and the copy of
unsigned_flagis then used for logging. (Bug #51426, Bug #11759138)
References: See also: Bug #49562, Bug #11757508.
Microsoft Windows: On Windows, an IPv6 connection to the server could not be made using an IPv4 address or host name. (Bug #52381, Bug #11760016)
Microsoft Windows: On Windows, the
my_rename()function failed to check whether the source file existed. (Bug #51861, Bug #11759540)
Microsoft Windows: On Windows, mysqlslap crashed for attempts to connect using shared memory. (Bug #31173, Bug #11747181, Bug #59107, Bug #11766072)
The embedded server could crash when determining which directories to search for option files. (Bug #55062, Bug #11762465)
Performance Schema code was subject to a buffer overflow. (Bug #53363)
Subquery execution for
EXPLAINcould be done incorrectly and raise an assertion. (Bug #52317, Bug #11759957)
There was a mixup between
ORDER BYconcerning which indexes should be considered or permitted during query optimization. (Bug #52081, Bug #11759746)
EXPLAINoutput for subquery lines could be missing information. (Bug #50257, Bug #11758106)
CREATE USERstatements were written to the binary log in cleartext rather than in ciphertext. (Bug #50172)
BLACKHOLEstorage engine failed to load on Solaris and OpenSolaris if DTrace probes had been enabled. (Bug #47748, Bug #11755909)
Some error messages included a literal
mysqldatabase name rather than a parameter for the database name. (Bug #46792, Bug #11755079)
ER_TABLEACCESS_DENIED_ERRORerror message, the command name parameter could be truncated. (Bug #45355, Bug #11753840)
To forestall the occurrence of possible relocation errors in the future,
libdbughave been changed from normal libraries to “noinst” libtool helper libraries, and are no longer installed as separate libraries. (Bug #29791, Bug #11746931)
A suboptimal query execution plan could be chosen when there were several possible
refaccesses. Now preference is given to the keys that match the most parts and choosing the best one among them. (Bug #26106, Bug #11746406)
Searches for data on a partial index for a column using the
utf8character set failed. (Bug #24858)
For queries with
FORCE INDEXwas not ignored as it should have been when it would result in a more expensive query execution plan. (Bug #18144, Bug #11745649)