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 theauto.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 theserver_uuidsystem variable.

MySQL replication masters and slaves know each other's UUIDs. The value of a slave's UUID can be read in the output ofSHOW SLAVE HOSTS. After a slave is started usingSTART SLAVE, the value of the master's UUID is available on the slave in the output ofSHOW 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 theALTER TABLE ... EXCHANGE PARTITIONstatement. This can be used, for example, for importing and exporting partitions.

For more information and examples, seeExchanging Partitions and Subpartitions with Tables.

Replication:These unused and deprecated items have been removed: the--init-rpl-roleand--rpl-recovery-rankoptions, therpl_recovery_ranksystem variable, and theRpl_statusstatus variable. (Bug #54649, Bug #11762095)

References: See also: Bug #34437, Bug #11747900, Bug #34635, Bug #11747961.

Replication:TheSHOW SLAVE STATUSstatement now has aMaster_Info_Filefield indicating the location of themaster.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 newMASTER_DELAYoption forCHANGE MASTER TOto set the delay toNseconds:

CHANGE MASTER TO MASTER_DELAY =N;

An event received from the master is not executed until at leastNseconds later than its execution on the master.

START SLAVEandSTOP SLAVEtake effect immediately and ignore any delay.RESET SLAVEresets the delay to 0.

SHOW SLAVE STATUShas three new fields that provide information about the delay:

When the slave SQL thread is waiting for the delay to elapse before executing an event,SHOW PROCESSLISTdisplays itsStatevalue asWaiting until MASTER_DELAY seconds after master executed event.

Therelay-log.infofile now contains the delay value, so the file format has changed. SeeReplication 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:

For additional information, seeDelayed Replication. (Bug #28760, Bug #11746794)

The Romansh locale'rm_CH'is now a permissible value for thelc_time_namessystem variable. (Bug #50915, Bug #11758678)

mysqlbinlognow has a--binlog-row-event-max-sizeoption to enable large row events to be read from binary log files. (Bug #49932)

mysqldumpnow has an--add-drop-triggeroption which adds aDROP TRIGGER IF EXISTSstatement before each dumped trigger definition. (Bug #34325, Bug #11747863)

Vietnamese collations were added for the Unicode character sets. Those based on Unicode Collation Algorithm 5.2.0 have names of the formxxx_vietnamese_520_ci(for example,utf8_vietnamese_520_ci). Those based on Unicode Collation Algorithm 4.0.0 have names of the formxxx_vietnamese_ci(for example,utf8_vietnamese_ci). These collations are the same as the correspondingxxx_unicode_520_ciandxxx_unicode_cicollations except for precomposed characters which are accented versions of“A”,“D”,“E”,“O”, and“U”. There is no change to ideographic characters derived from Chinese. There are no digraphs.

Unicode名称排序现在可能包括一个版本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.

LOWER()andUPPER()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 optionalversionattribute intags to indicate the UCA version on which the collation is based. If theversionattribute is omitted, its default value is4.0.0. SeeAdding a UCA Collation to a Unicode Character Set.

In MySQL 5.5, settingoptimizer_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 Unicode character sets now have axxx_german2_cicollation that provides DIN-2 (phone book) ordering (for example,utf8_german2_ci). SeeUnicode Character Sets.

mysqlbinlognow has the capability to back up a binary log in its original binary format. When invoked with the--read-from-remote-serverand--rawoptions,mysqlbinlogconnects to a server, requests the log files, and writes output files in the same format as the originals. SeeUsing 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. SeeString 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. Nowunsigned_flagis copied when the user variable value is copied, and the copy ofunsigned_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, themy_rename()function failed to check whether the source file existed. (Bug #51861, Bug #11759540)

Microsoft Windows:On Windows,mysqlslapcrashed 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 forEXPLAINcould be done incorrectly and raise an assertion. (Bug #52317, Bug #11759957)

There was a mixup betweenGROUP BYandORDER BYconcerning which indexes should be considered or permitted during query optimization. (Bug #52081, Bug #11759746)

Therefcolumn ofEXPLAINoutput for subquery lines could be missing information. (Bug #50257, Bug #11758106)

Passwords forCREATE USERstatements were written to the binary log in cleartext rather than in ciphertext. (Bug #50172)

TheBLACKHOLEstorage engine failed to load on Solaris and OpenSolaris if DTrace probes had been enabled. (Bug #47748, Bug #11755909)

Some error messages included a literalmysqldatabase name rather than a parameter for the database name. (Bug #46792, Bug #11755079)

In theER_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,libmysys,libmystrings, andlibdbughave been changed from normal libraries to“noinst”libtoolhelper 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 possiblerangeandref访问。现在是优先考虑的关键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 theutf8character set failed. (Bug #24858)

For queries withGROUP BY,FORCE INDEXwas not ignored as it should have been when it would result in a more expensive query execution plan. (Bug #18144, Bug #11745649)