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Mysql 5.7.17揭橥了,重要修复:

 

What is the difference between MySQL Replication and MySQL Cluster?

近年来绝地求生这么些游戏太火了,当自个儿问我的情大家你们闲时在干嘛,基本上告诉小编的答案都以在"吃鸡"啊!想必好些个亲密的朋友们也玩,那必将应该知道绝地求生中有把枪叫AWM。此枪加害裸132点,爆头330,固然三级头爆头必死,无防弹衣也许防弹衣有破损,一枪死。是这几个游戏中威力最大的狙击×××,足足是98K的两倍。

    Group Replication is know as an up to date HA(High Availablity) solution which is supported in official version of MySQL 5.7 since Dec. 2016.It's similar with the other two tools —— MHA(By Yoshinorim) & PXC(By Percona),but not as same as them. Group Replication(I'll call it MGR later) provides features below:

Changes in MySQL 5.7.17 (2016-12-12, General Availability)

  • Compilation Notes

  • MySQL Enterprise Notes

  • Packaging Notes

  • Security Notes

  • Test Suite Notes

  • Functionality Added or Changed

  • Bugs Fixed

Compilation Notes

  • For GCC versions higher than 4.4, -fno-expensive-optimizations was replaced with -ffp-contract=off, which has the effect of enabling more optimizations. Thanks to Alexey Kopytov for the patch. (Bug #24571672, Bug #82760)

MySQL Enterprise Notes

  • Enterprise Encryption for MySQL Enterprise Edition now enables server administrators to impose limits on maximum key length by setting environment variables. These can be used to prevent clients from using excessive CPU resources by passing very long key lengths to key-generation operations. For more information, see Enterprise Encryption Usage and Examples. (Bug #19687742)

Packaging Notes

  • RPM packages now are built with -DWITH_NUMA=ON for platforms with NUMA support: OEL higher than EL5, Fedora, SLES, Docker. (Bug #24689078)

Security Notes

  • Incompatible Change: These changes were made to mysqld_safe:

    • Unsafe use of rm and chown澳门新浦京娱乐场网站共同复制,7组复制技能。 in mysqld_safe could result in privilege escalation. chown now can be used only when the target directory is /var/log. An incompatible change is that if the directory for the Unix socket file is missing, it is no longer created; instead, an error occurs. Due to these changes, /bin/bash is required to runmysqld_safe on Solaris. /bin/sh is still used on other Unix/Linux platforms.

    • The --ledir option now is accepted only on the command line, not in option files.

    • mysqld_safe ignores the current working directory.

    Other related changes:

    • Initialization scripts that invoke mysqld_safe pass --basedir explicitly.

    • Initialization scripts create the error log file only if the base directory is /var/log or /var/lib.

    • Unused systemd files for SLES were removed.

    (Bug #24483092, Bug #25088048)

    References: See also: Bug #24464380, Bug #24388753.

  • MySQL Server now includes a plugin library that enables administrators to introduce an increasing delay in server response to clients after a certain number of consecutive failed connection attempts. This capability provides a deterrent that slows down brute force attacks that attempt to access MySQL user accounts. For more information, see The Connection-Control Plugin.

  • OpenSSL is ending support for version 1.0.1 in December 2016; see . Consequently, MySQL Commercial Server builds now use version 1.0.2 rather than version 1.0.1, and the linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1 to version 1.0.2j. For a description of issues fixed in this version, see .

    This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which uses the yaSSL library instead.

Test Suite Notes

  • mysql-test-run.pl could not be run with --valgrind-option=--tool=custom_tool, for values of custom_tool such as massif or helgrind, because it added the options for memcheck that might not be understood by other tools. Also, the mysql-test-run.pl --callgrind option did not work because it supplied an invalid --base option tocallgrind. Thanks to Daniel Black for the patch on which the fixes were based. (Bug #23713613, Bug #82039)

Functionality Added or Changed

  • Incompatible Change; Partitioning: The generic partitioning handler in the MySQL server is deprecated, and will be removed in MySQL 8.0. As part of this change, the mysqld --partition and --skip-partition options as well as the -DWITH_PARTITION_STORAGE_ENGINE build option are also deprecated, and will later be removed; partitioning will no longer be shown in the INFORMATION_SCHEMA.PLUGINS table or in the output of SHOW PLUGINS.

    Following the removal of the generic partitioning handler, the storage engine used for a given table will be expected to provide its own (“native”) partitioning handler as the InnoDB and NDB storage engines currently do. Currently, no other MySQL storage engines provide native partitioning support, nor is any planned for any other storage engines in current or development versions of MySQL.

    Use of tables with nonnative partitioning now results in an ER_WARN_DEPRECATED_SYNTAX warning. Also, the server performs a check at startup to identify tables that use nonnative partitioning; for any found, the server writes a message to its error log. To disable this check, use the --disable-partition-engine-check option.

    To prepare for migration to MySQL 8.0, any table with nonnative partitioning should be changed to use an engine that provides native partitioning, or be made nonpartitioned. For example, to change a table to InnoDB, execute this statement:

    ALTER TABLE table_name ENGINE = INNODB;
    
  • InnoDB: By default, InnoDB reads uncommitted data when calculating statistics. In the case of an uncommitted transaction that deletes rows from a table, InnoDB excludes records that are delete-marked when calculating row estimates and index statistics, which can lead to non-optimal execution plans for other transactions that are operating on the table concurrently using a transaction isolation level other than READ UNCOMMITTED. To avoid this scenario, a new configuration option,innodb_stats_include_delete_marked, can be enabled to ensure that InnoDB includes delete-marked records when calculating persistent optimizer statistics. (Bug #23333990)

  • The systemd service file for mysqld now includes a Documentation value in the [Unit] section to provide a link to the systemd documentation in the MySQL Reference Manual. (Bug #24735762)

  • Unit testing now uses Google Mock 1.8. (Bug #24572381, Bug #82823)

  • If mysqld is invoked with --daemonizestdout and stderr are redirected to /dev/null if connected to a terminal type device, so that mysqld can behave as a true daemon. (Bug #21627629)

  • The libmysqld embedded server library is deprecated and will be removed in a future version of MySQL.

  • MySQL Group Replication is a new MySQL plugin that enables you to create a highly available distributed MySQL service across a group of MySQL server instances, with data consistency, conflict detection and resolution, and group membership services all built-in. By using a powerful new group communication service, which provides an implementation of the popular Paxos algorithm, the group of MySQL Server instances automatically coordinates on data replication, consistency, and membership. This provides all of the built-in mechanisms necessary for making your MySQL databases highly available.

    By default Group Replication operates in single-primary mode where a single server instance, called the primary, accepts write requests. The remaining server instances in the group, called secondaries, function as replicas of the primary. In the event of an unexpected failure of the primary, an automatic primary election process takes place and one of the secondaries is elected as the new primary. Group Replication also supports virtually synchronous multi-primary replication, with certain considerations and restrictions, which offers update everywhere functionality. In this mode all members are equal and you can distribute your reads and writes across all MySQL Server instances in the group.

    Regardless of the operating mode, Group Replication provides a dynamic membership service that relies on distributed failure detection. Server instances can join and leave the group dynamically, and you can query the group's membership list at any point through Performance Schema tables. Server instances that join the group automatically synchronize their state with the group by doing an automatic point-in-time recovery which ensures that they reach synchrony with the group.

    MySQL Group Replication's virtually synchronous replication is also a fully integrated part of MySQL, using the InnoDB storage engine, the Performance Schema tables, standard GTIDs and the well known replication infrastructure (binary and relay logs, multi-source replication, multi-threaded slave execution, etc.), which makes it a familiar and intuitive experience for existing MySQL users and makes it very easy to integrate with MySQL's standard asynchronous and semisynchronous replication, allowing you to mix and match as needed to create varied and complex replication topologies.

Bugs Fixed

  • Incompatible Change: A change made in MySQL 5.7.8 for handling of multibyte character sets by LOAD DATA was reverted due to the replication incompatibility (Bug #24487120, Bug #82641)

    References: See also: Bug #23080148.

  • NDB Cluster: MySQL Cluster encountered race conditions compiling lex_hash.h. (Bug #24931655, Bug #83477)

  • InnoDB: The INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS table reported NULL for a foreign key constraint name (UNIQUE_CONSTRAINT_NAME) after restarting the server. (Bug #25126722)

  • InnoDB: A prepared XA transaction was rolled back by a high priority transaction. The high priority transaction should wait if the blocking transaction is in a prepared state. (Bug #25032066)

  • InnoDB: InnoDB passed an invalid argument to syscall(SYS_futex). (Bug #24923840, Bug #83375)

  • InnoDB: On a MySQL 64-bit build on Windows, a file I/O retry result was misinterpreted due to a missing cast necessary for the correct operation of the retry path, resulting in a failing assertion and operating system error. (Bug #24711351)

  • InnoDB: The GCC mach_parse_compressed function should load one to five bytes depending on the value of the first byte. Due to a GCC bug, GCC 5 and 6 emit code to load four bytes before the first byte value is checked (GCC Bug #77673). A workaround prevents this behavior.

    Thanks to Laurynas Biveinis for the patch. (Bug #24707869, Bug #83073)

  • InnoDB: Due to a glibc bug, short-lived detached threads could exit before the caller had returned from pthread_create(), causing a server exit.

    Thanks to Laurynas Biveinis for the patch. (Bug #24605956, Bug #82886)

  • InnoDB: After increasing the value of innodb_undo_logs and restarting the server, the number of active undo tablespaces was not increased when assigning undo tablespaces to newly allocated rollback segments. (Bug #24488141)

  • InnoDB: InnoDB incorrectly reported an error about missing encryption when restoring pages from the doublewrite buffer during recovery. (Bug #24471076)

  • InnoDB: A cached undo segment was not removed from the rollback segment history during a slow shutdown. (Bug #24450908)

  • InnoDB: An error during a table-rebuilding operation on a table with only a generated clustered index (GEN_CLUST_INDEX) raised and assertion due to an error called with an invalid key name. (Bug #24444831)

  • InnoDB: Rotating the tablespace encryption master key while the server is in read-only mode raised an assertion instead of displaying an error message. (Bug #24404091)

  • InnoDB: On a table without an explicitly defined primary key, InnoDB did not replace the implicit clustered index (GEN_CLUST_INDEX) when a unique key was defined on a NOT NULL column. (Bug #24397406)

  • InnoDB: A high priority transaction involving a foreign key constraint check was not able to kill a lower priority blocking transaction. (Bug #24347476)

  • InnoDB: Page cleaner threads asserted due to a regression related to the adaptive hash index feature. (Bug #24346574)

    References: This issue is a regression of: Bug #21407023.

  • InnoDB: InnoDB failed to free memory used by the full-text optimizer thread. (Bug #24331265)

  • InnoDB: When adding a new index, the server dropped an internally defined foreign key index and attempted to use a secondary index defined on a generated virtual column as the foreign key index, causing a server exit. InnoDB now permits a foreign key constraint to reference a secondary index defined on a generated virtual column. (Bug #23533396)

  • InnoDB: An INFORMATION_SCHEMA.FILES query resulted in a server exit due to a race condition with a concurrent tablespace creation operation. (Bug #23477214)

  • InnoDB: A table-copying online ALTER TABLE operation on a ROW_FORMAT=REDUNDANT table with indexed virtual columns raised an assertion. (Bug #22018745)

  • InnoDB: SHOW ENGINE INNODB STATUS output showed a “cleaning up” state for an idle thread. Thread state information was not reset after statement execution. (Bug #21974225, Bug #78777)

  • InnoDB: After a server restart, concurrent INSERT operations a table with an auto-increment primary key resulted in a duplicate entry error. The current auto-increment value was not changed after auto_increment_increment and auto_increment_offset settings were modified. (Bug #20989615, Bug #76872)

  • Replication: When using XA transactions, if a lock wait timeout or deadlock occurred for the applier (SQL) thread on a replication slave, the automatic retry did not work. The cause was that while the SQL thread would do a rollback, it would not roll the XA transaction back. This meant that when the transaction was retried, the first event was XA START which was invalid as the XA transaction was already in progress, leading to an XAER_RMFAIL error. (Bug #24764800)

    References: See also: Bug #24923091, Bug #24966941.

  • Replication: The group commit update of GTIDs has been refactored to improve performance on workloads with many small transactions. (Bug #24398760)

  • Replication: If the relay_log option was not specified in a configuration file, the relay_log_basename variable was being internally constructed on the fly using hostname but the relay_log_basename variable was not set. When a slave tried to access this uninitialized variable it resulted in an unexpected halt of the server. (Bug #24352667)

  • Replication: For servers built with yaSSL, using group replication with secure connections could result in timeout failures waiting for view delivery. (Bug #23592214)

  • Replication: Tables with special DEFAULT columns, such as DEFAULT CURRENT_TIMESTAMP, that existed only on a slave were not being updated when using row-based replication (binlog_format=ROW). (Bug #22916743)

  • Replication: An XA PREPARE statement that failed during the intermediate steps could lead to an inconsistent XA transaction state, where ID = -1 but the binlogged flag was set to true. This caused asserts while executing XA COMMIT and XA ROLLBACK queries. (Bug #22915670)

  • Replication: Enabling semisynchronous replication when a server was during the commit stage could cause the master to stop unexpectedly. This was related to the patch for Bug# 75570. (Bug #22202516)

  • Replication: The number of generated unwanted fseeks into the binary log file being replicated to a slave has been reduced. (Bug #83226, Bug #24763579)

  • Replication: The rpl.rpl_binlog_errors test was failing sporadically on Windows. (Bug #82302, Bug #24330138)

  • Replication: When binlog_group_commit_sync_delay was set to a value between 1 and 9, if binlog_group_commit_sync_no_delay_count was set to a value greater than 1, and the number of transaction commits was less than binlog_group_commit_sync_no_delay_count, these commits hung forever if no more commits were received; and ifbinlog_group_commit_sync_no_delay_count was set to 0, all transaction commits hung forever. (Bug #80652, Bug #22891628)

  • Replication: Using semisynchronous replication was not possible with more than 1024 simultaneous connections. (Bug #79865, Bug #23581389)

  • Some Linux startup scripts did not process the datadir setting correctly. (Bug #25159791)

  • CREATE TABLE with a DATA DIRECTORY clause could be used to gain extra privileges. (Bug #25092566)

  • CMake now avoids configuring the -fexpensive-optimizations option for GCC versions for which the option triggers faulty shift-or optimizations. (Bug #24947597, Bug #83517)

  • OEL RPM packages now better detect which platforms have multilib support (for which 32-bit and 64-bit libraries can be installed). Thanks to Alexey Kopytov for the patch. (Bug #24925181, Bug #83457)

  • OEL RPM packages now better detect which platforms do not have multilib support (for which 32-bit and 64-bit libraries can be installed). Thanks to Alexey Kopytov for the patch. (Bug #24916428, Bug #83428)

  • Information about building MySQL 5.6 compatibility libraries in the MySQL 5.7 and higher .spec file is needed only for building libmysqlclient and libmysqld. Information about building the InnoDB memcached plugin was removed. (Bug #24908345, Bug #83409)

  • Compiling MySQL using Microsoft Visual Studio 2015 Version 14.0.25420.1 in relwithdebinfo mode failed with linking errors. (Bug #24748505)

  • To better provide atomic file creation, Debian packaging scripts now use the coreutils install command rather than touchchmod, and chown. (Bug #24688682)

  • For SLES packages, a typo in the installation script postamble prevented some cleanup from occurring. (Bug #24605300, Bug #82389)

  • Warnings occurring during CREATE TABLE ... SELECT could cause a server exit. (Bug #24595992)

  • For LOAD DATA statements, input data with too many column values produced only a warning, rather than an error as in MySQL 5.6. An error now occurs. (Bug #24577194, Bug #82830)

  • For segmentation faults on FreeBSD, the server did not generate a stack trace. (Bug #24566529, Bug #23575445, Bug #81827)

  • The .mylogin.cnf option file is intended for use by client programs, but the server was reading it as well. The server no longer reads it. (Bug #24557925)

  • The X Plugin was built with compilation options different from other plugins. (Bug #24555770, Bug #82777)

  • If mysqladmin shutdown encountered an error determining the server process ID file, it displayed an error message that did not clearly indicate the error was nonfatal. It now indicates that execution continues. (Bug #24496214)

  • The data structure used for ZEROFILL columns could experience memory corruption, leading eventually to a server exit. (Bug #24489302)

  • Operation of the mysql-multi.server.sh script was based on my.cnf in the data directory. That option file is no longer used, so mysql-multi.server.sh has been removed. (Bug #24487870)

  • Use of very long subpartition names could result in a server exit. Now partition or subpartition names larger than 64 characters produce an ER_TOO_LONG_IDENT error. (Bug #24400628, Bug #82429)

  • The Gis_wkb_vector<Gis_point> copy constructor was not explicitly instantiated, causing build problems for the Intel compiler. (Bug #24397833, Bug #82358)

  • Upgrading from MySQL 5.6 to 5.7.13 and then to 5.7.14 resulted in an incorrect column order in the mysql.slave_master_info system table. (Bug #24384561, Bug #82384)

  • The AppArmor profile installed by Ubuntu packages was missing an entry permitting libnuma to read a /sys hierarchy path, resulting in server startup failure. (Bug #23854929)

  • For an INSERT statement for which the VALUES list produced values for the second or later row using a subquery containing a join, the server could exit after failing to resolve the required privileges. (Bug #23762382)

  • Infinite recursion could occur if the audit_log plugin signalled an error while handling an error. (Bug #23717558, Bug #82052)

  • MySQL now uses readdir() rather than readdir_r(). The latter has been deprecated since glibc 2.24 and caused debug builds of MySQL and builds using GCC 6.1 to fail.

    Additionally, several problems resulting in GCC 6.1 compiler warnings were corrected. (Bug #23708395, Bug #24437737, Bug #82515, Bug #24459890, Bug #25103242)

  • For audit log events in the connection class, the connection_type value was available only for connect events. The value is now available in connect, disconnect, and change-user events. (Bug #23541550)

  • On Solaris, gettimeofday() could return an invalid value and cause a server shutdown. (Bug #23499695)

  • The keyring_file plugin could attempt to write keys to its storage file when the file did not exist. To ensure that keys are flushed only when the correct storage file exists, keyring_file now stores a SHA-256 checksum of the keyring in the file. Before updating the file, the plugin verifies that it contains the expected checksum. (Bug #23498254)

  • START GROUP REPLICATION uses stacked Srv_session and did not return to the correct thread. START GROUP REPLICATION and STOP GROUP REPLICATION are now removed from the list of permitted commands. (Bug #23337984)

  • A union query resulting in tuples larger than max_join_size could result in a server exit. (Bug #23303485)

  • The optimizer could choose ref access on a secondary index rather than range access on the primary key, even when the cost was higher. (Bug #23259872, Bug #81341)

  • For a query with ORDER BY and LIMIT, an optimizer trace did not record the optimizer's switch to a different index. (Bug #23227428, Bug #81250)

  • For some deeply nested expressions, the optimizer failed to detect stack overflow, resulting in a server exit. (Bug #23135667)

  • The sys schema ps_truncate_all_tables() function did not work with read_only enabled or for users with the SUPER privilege with super_read_only enabled, due to errors attempting to truncate Performance Schema tables. The server now skips the read_only/super_read_only check for Performance Schema tables, with the result thatps_truncate_all_tables() will work under such configurations. (Bug #23103937, Bug #81009)

  • For sessions created through the X Plugin, incorrect thread attachment/detachment could cause a server exit. (Bug #23057045)

  • When a JSON value consisted of a large sub-document wrapped in many levels of JSON arrays, objects, or both, serialization of the JSON value sometimes required an excessive amount time to complete. (Bug #23031146)

  • A binary (in-place) upgrade from MySQL 5.6 to 5.7 followed by a data export performed using mysqlpump resulted in an Invalid default value for date_column error for attempts to reload the dump file. (Bug #22919028, Bug #80706)

  • SQL statements executed through the X Plugin were not instrumented in the Performance Schema. (Bug #22859462)

  • DROP INDEX operations could fail due to inconsistent handling of index prefix lengths for TEXT-type columns (TINYTEXT and so forth). (Bug #22740093, Bug #80392)

  • The innodb_numa_interleave system variable was erroneously available on some systems that were not NUMA-enabled. Thanks to Tomislav Plavcic for the patch.

    CMake now sets the default WITH_NUMA value based on whether the current platform has NUMA support. For platforms without NUMA support, 澳门新浦京娱乐场网站,CMake behaves as follows:

    • With no NUMA option (the normal case), CMake continues normally, producing only this warning: NUMA library missing or required version not available

    • With -DWITH_NUMA=ONCMake aborts with this error: NUMA library missing or required version not available

    (Bug #22678436, Bug #80288)

  • When taking the server offline, a race condition within the Performance Schema could lead to a server exit. (Bug #22551677)

  • On macOS, if a table with an associated trigger was renamed to a new name containing both lowercase and uppercase characters, DROP TRIGGER for the trigger resulted in an ER_NO_SUCH_TABLE error for the table. (Bug #22512899, Bug #79873)

  • In the MYSQL_FIELD C API structure, the org_table value for derived tables was *, which could cause failure for queries that depend on this value. The org_table value for views and derived tables now is set as follows: If the column is selected from a view, org_table names the view. If the column is selected from a derived table, org_table names the base table. If a derived table wraps a view, org_table still names the base table. If the column is an expression, org_table is the empty string. (Bug #22364401, Bug #79641)

  • The Performance Schema events_statements_summary_by_digest table could contain multiple rows for the same statement digest and schema combination, rather than the expected single (unique) row. (Bug #22320066, Bug #79533)

  • For Performance Schema system and status variable tables, variable values expressed in a character set different from utf8 could be truncated or incorrect. (Bug #22313205)

  • Queries that were grouped on a column of a BLOB-based type, and that were ordered on the result of the AVG()VAR_POP(), or STDDEV_POP() aggregate function, returned results in the wrong order if InnoDB temporary tables were used. (Bug #22275357, Bug #79366)

  • On Ubuntu, error messages were displayed during upgrades from Community to Commercial packages that made it appear as though mysqld and my_print_defaults had not been installed. Those messages were spurious and have been silenced. (Bug #21807248)

  • An invalid string value in the WHERE clause of an UPDATE statement, caused an index scan rather than a range scan to be used. For values not present in the index, this could be much slower. Now the optimizer determines this to be an “impossible WHERE” condition. (Bug #21032418, Bug #76933)

  • The return value from an fread() call was not checked. (Bug #20671150)

  • An in-place ALTER TABLE operation failed to report an error when adding a DATE or DATETIME column under these conditions: a) the column was NOT NULL and no default value was supplied; b) strict and NO_ZERO_DATE SQL modes were enabled; c) the table was not empty.

    An ALTER TABLE operation failed with an error rather than a warning when adding a DATE or DATETIME column under these conditions: a) the column was NOT NULL and no default value was supplied; b) strict SQL mode was enabled and NO_ZERO_DATE SQL mode was not enabled; c) the table was not empty. (Bug #16888677)

听大人讲历史经验,percona server 应该会在1个月后左右公布。

Preface

Discussion

那就是说在MySQL领域有没有那样一把威力超大的“枪”呢~答案是必须有啊!但老张先问你们二个难题。

 

 

MySQL currently supports two different solutions for creating a high availability environment and achieving multi-server scalability.
MySQL Replication

试问你搭建MySQL复制的时候,还在试行备份复苏,在从库举行change master to的操作嘛?假使是那你可就着实落后了。

  • *high consistency
    *

    As we all know,there're three kinds of replication in MySQL nowadays.Such as,asynchronous replication,(full)synchronous replication,semi-synchronous replication.What's the difference between them?First of all,let's see the intact architecture picture of MySQL replication:

The first form is replication, which MySQL has supported since MySQL version 3.23. Replication in MySQL is currently implemented as an asyncronous master-slave setup that uses a logical log-shipping backend.

本章介绍MySQL官方推荐的一款高可用集群方案MySQL Group Replication。简称:名爵奥迪Q5(组复制)。它是官方推出的一种基于Paxos协议的动静机复制,透彻化解了遵照守旧的异步复制和半一同复制中多少一致性难点不恐怕确定保证的图景。也让MySQL数据库涉及的小圈子更广,深透具有了开辟互连网金融行业的大门。2015年七月MySQL Group Replication推出了第贰个GA版本公布在MySQL5.7.17中。但如今一直投入到生育情形中应用,危害依旧比非常大。提出等其进一步成熟今后,大家再真正投入使用。

 

 

A master-slave setup means that one server is designated to act as the master. It is then required to receive all of the write queries. The master then executes and logs the queries, which is then shipped to the slave to execute and hence to keep the same data across all of the replication members.

随着MySQL8.0本子就要与我们汇合,再同盟官方渐渐成熟的高可用集群 Group Replication方案,到那时候再看看什么人照旧大家MySQL的挑战者,全都不在了!MySQL数据库正是小编的迷信,爱您无怨无悔。

    MGR protocol lies on the algorithm of Paxos(Which is a kind of consensus protocol usually be used in distributed system and presented by Mr.Lamport.) to guarantee data consistency.What's Paxos?There's something about it below:

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Replication is asyncronous, which means that the slave server is not guaranteed to have the data when the master performs the change. Normally, replication will be as real-time as possible. However, there is no guarantee about the time required for the change to propagate to the slave.

MG奇骏组复制原理

    theory of Paxos: http://www.the-paper-trail.org/post/2009-02-03-consensus-protocols-paxos/

 

Replication can be used for many reasons. Some of the more common reasons include scalibility, server failover, and for backup solutions.

先来研商如何叫做组复制。组复制是一种可用于贯彻容错系统的技巧。复制组是三个透过新闻传递相互交互的server集群。复制组由四个server成员组成,如下图的master1,master2,master3,全体成员独立落成各自的业务。当客户端头阵起贰个翻新专门的学业,该事务先在该地实施,实行到位今后将在发起对业务的提交操作了。在还向来不当真付诸在此以前须求将发出的复制写集播放出去,复制到其余成员。假如争论检验成功,组内决定该业务可以交给,别的成员能够利用,不然就回滚。最终,那意味全部组内成员以同样的逐条接受同一组事务。因而组内成员以一样的一一应用同样的改换,有限支撑组内数据强一致性。

    Mr Lamport's introduction on wiki: 

What will client do?

Scalibility can be achieved due to the fact that you can now do can do SELECT queries across any of the slaves. Write statements however are not improved generally due to the fact that writes have to occur on each of the replication member.

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    MGR provides a built-in membership 

  • generates transactions

  • commits transactions to master

  • receives results from master

Failover can be implemented fairly easily using an external monitoring utility that uses a heartbeat or similar mechanism to detect the failure of a master server. MySQL does not currently do automatic failover as the logic is generally very application dependent. Keep in mind that due to the fact that replication is asynchronous that it is possible that not all of the changes done on the master will have propagated to the slave.

MG凯雷德组复制形式

service which can strongly coordinate the servers in the same group to do switchover between master and slave automatically with high efficiency and strong consistency.All members in the same group will communicate with each other from time to time by GSC protocols.The group members always come up to an agreement in an order of global transaction sequence in order to decide whether to commit or abort transactions when commit operations happen.

What will master do?

MySQL replication works very well even across slower connections, and with connections that aren't continuous. It also is able to be used across different hardware and software platforms. It is possible to use replication with most storage engines including MyISAM and InnoDB.
MySQL Cluster

组复制能够在三种情势下运营。 在单主方式下,组复制具备自动选主功效,每一遍只有一个server成员接受创新,别的成员只提供读服务。在多主格局下运作时,全部的 server 成员都足以而且接受创新,没有基本之分,成员剧中人物是一丝一毫对等的。 组复制暗中同意情况下是单主形式,我们能够透过安装参数group_replication_single_primary_mode=off,让其变为多主格局。本章的实战部分正是以多主格局实行MGHighlander复制的搭建。

 

  • executes transactions
  • generates binary logs
  • dump thread sends contents(binary logs) to slave
  • returns results to client

MySQL Cluster is a shared nothing, distributed, partitioning system that uses synchronous replication in order to maintain high availability and performance.

MG奥迪Q5性子介绍

  • *high flexibility
    *

What will slave do?

MySQL Cluster is implemented through a separate storage engine called NDB Cluster. This storage engine will automatically partition data across a number of data nodes. The automatic partitioning of data allows for parallelization of queries that are executed. Both reads and writes can be scaled in this fashion since the writes can be distributed across many nodes.

成功了真正的多节点读写的集群方案。

    

  • connects to master
  • IO Thread asks for data(binary logs) and gets them
  • generates relay logs
  • SQL Thread applies data(relay logs)

Internally, MySQL Cluster also uses synchronous replication in order to remove any single point of failure from the system. Since two or more nodes are always guaranteed to have the data fragment, at least one node can fail without any impact on running transactions. Failure detection is automatically handled with the dead node being removed transparent to the application. Upon node restart, it will automatically be re-integrated into the cluster and begin handling requests as soon as possible.

基于原生复制及paxos协议的组复制技艺,并以插件的措施提供,达成了多少的强一致性

    MGR supports both single-primary and multi-primary mode.In the single-primary mode,there's a machenism called "primary election" automatically while failure is detected and only the primary server can update data simultanuously.In the multi-primary mode,update can be done on all the servers in the group even though they update data concurrently.You can choose the appropriate way to implement your MySQL Servers.

Method of different MySQL Replication

There are a number of limitations that currently exist and have to be kept in mind while deciding if MySQL Cluster is the correct solution for your situation.

出于是多节点读写,failover切换变得尤为简明

 

 

Currently all of the data and indexes stored in MySQL Cluster are stored in main memory across the cluster. This does restrict the size of the database based on the systems used in the cluster. Work is underway to allow data to be stored on disk and will most likely appear in MySQL version 5.1.

充实删除节点,自动完成联合数据和立异组内消息的操作。扩张性地加强

  • ***high fault-tolerance

    Generally speaking,the data changed on master will be continuously sent to slave.So the data on slave seems to be equal with the master.This mechanism is usually used to backup on slave(reduce the pressure of master),construct HA architecture(failover or separate reading/writing operations),etc.

MySQL Cluster is designed to be used on an internal network as latency is very important for response time. As a result, it is not possible to run a single cluster across a wide geographic distance. In addition, while MySQL Cluster will work over commodity network setups, in order to attain the highest performance possible special clustering interconnects can be used.

虽说在MGXC60的多主形式下,受到无法支撑串行隔开分离等级和不协理外键级联操作的限定条件。而且这两天MySQL版本中对DDL语句操作不也许落到实处回滚,导致MG福特Explorer无法对DDL语句做多少争辩核实,所以DDL语句在MG奥迪Q5中并发实践存在隐患。但那几个都无法阻止MGMurano的发表所带来的创导新时期的含义。让大家共同有的时候间待这一个追求极致完美的MySQL数据库,今后更进一步灿烂。

    

    Nevertheless,on account of different reasons,slave frequently defers in almost all the scenarios what's often grumbled by MySQL dba.Below are different kinds of MySQL replication.Let's see the details.

MGSportage搭建实战演练

   Only if most of your servers crash,the service will continuously proceed.There's an "failure detector" machenism when fault occurs or the servers in group don't get privilege to update data.that also prevents "brain-split" when one member cannot communicate with others in the same group(Which usually caused by network failure or something else). it's recommended to implement MGR with three server at least,as the number of tolerance depend on the formula:n=2f 1.For instance,there's five members in the MGR group,so the tolerance is two.*

  • asynchronous replication

条件介绍:这里我们筹算多少个节点,数据库版本选择MySQL5.7.17

 

    **Since MySQL 3.2.22,this kind of replication was supported with statement format of binary log.Then,untill MySQL 5.1.5,row format of binary log was supported either.The mechanism of it is that as soon as the master dump thread has sent the binary logs to the slave,the master server returns the result to client.There's nothing to guarantee the binary logs are normally received by the slave(maybe the network failure occurs simultaneously).So it's unsafe in consistency what  means your transactions will lose in the replication.This is also the original replication of MySQL.Here's the picture about the procedure:

数据库IP地址 数据库版本音信 主机名 Server-id

  • high scalability

  •       One server in group can be replicated from another one automatically until it become equal when adding or removing it.MGR will maintain a view which contains informations about these group members if they changes,All the members join or leave the group voluntarilly or not will dynamically reconfigure the view.*

 

192.168.56.101MySQL-5.7.17node21013306192.168.56.102MySQL-5.7.17node31023306192.168.56.103MySQL-5.7.17proxysql1033306

       

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实战第1步:

    In order to distinguish MGR and traditional replication technology,let's see the pictures below:

1. Client sends dml operations to the master while the transaction starts.

在四个节点上实施安装MySQL5.7操作。(此步省略,实际情况请见书中第一局地次之章)

 

2. Master executes these dml operations from client in transaction.

实战第2步:

Asynchronous Replication:

3. Generates some binary logs which contains the transaction information.

在多个节点上各自安装hostname和ip地址的照射关系

 

4. Master will return results to the client immediately after dump thread has sent these binary logs to slave.

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5. Slave receives the binary logs by IO_Thread and apply the relay logs by SQL_Thread.

实战第3步:

 

 

在三个节点上个别创制复制账号,命令如下

Semisynchronous Replication(after_sync):

    In step 4,master won't judge whether slave has received the binary logs (which are sent by itself) or not.If the master crashs suddenly after it has sent the binary logs,but slave does not receive them at all on account of network delay.Only if the slave takes over the application at this time,the committed transactions will miss which means data loss.This is not commonly acceptable in most important product systems especially in the financial ones.

GRANTREPLICATIONSLAVEON*.*TO'repl'@'192.168.56.%'IDENTIFIEDBY'123456';

 

  • synchronous replication

实战第4步:

***澳门新浦京娱乐场网站 6

    Synchronous replication requires master to return results to client only after the transactions have been committed by all the slaves(receive and apply).This method will severely lead to bad performance on master unless you can guarantee the slaves can commit immediate without any delay(infact it's tough).Now,the only solution of synchronous replication is still the MySQL NDB Cluster.Therefore,it's not recommended to use synchronous replication way.

在四个节点上分别安装GXC90插件,命令如下


  • semi-synchronous replication

INSTALLPLUGINgroup_replicationSONAME'group_replication.so';

  

    Semi-synchronous replication seems a workaround of above two method which can strongly increase the consistency between master and slave.It's supported since MySQL 5.5 and enhanced in MySQL 5.7.What's the mechanism of semi-sychronouos replication?Master is permitted to return the result to client merely after only one slave has received binary logs,write them to the relay logs and returns an ACK signal to master.There're two ways of it,that is,after_commit & after_sync.Let's see the difference of them:

零件安装落成以往,呈现结果:

    From the above two pictures,we can see that there's no HA function in the master-slave traditional replication(both asyn mode and semisync mode).whenever the master crashes,the service won't be available anymore.

 

root@db13:23:  [(none)]> show plugins;

 

after_commit(Since MySQL 5.5):

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    In most scenarios,master has one or more slaves.Commits of transactions take place merely on the master.Binlogs are transited(asynchronously).Each server has a full copy of data 'cause it shares nothing here.

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实战第5步:

 

    

在几个节点分别陈设各自的集群参数文件,配置完结现在重启数据库

Group Replication(multi-primary):

    In this method,master performs a commit before it receives ACK signal from slave.Let's suppose a situation that once master crashs after it commits a transaction but it hasn't receive the ACK signal from slave.Meanwhile,failover makes slave become the new master.How does the slave deal with then?Will the transaction lose?It depends.There're two scenarios:

192.168.56.101参数文件配置体现:(剩下八个节点同理)

 

  • Slave has received the binary log,and then turns it into relay log and applys it.There's no transaction loss.
  • Slave hasn't received the binary log,the transaction committed by master just now will lose,but the client won't fail(only inconsistent in replication).

Group Replication

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    Therefore,after_commit cannot guarantee lossless replication.after_commit is the default mode(actually it's the only mode can be use) which is supported by MySQL 5.5 & 5.6.

server_id=1013306gtid_mode=ONenforce_gtid_consistency=ONmaster_info_repository= TABLErelay_log_info_repository= TABLEbinlog_checksum= NONElog_slave_updates=ONlog_bin= binlogbinlog_format= ROWtransaction_write_set_extraction= XXHASH64loose-group_replication_group_name='1f2cee29-f9a2-11e7-8cbb-08002783b39d'loose-group_replication_start_on_boot=offloose-group_replication_local_address='node2:33061'loose-group_replication_group_seeds='node2:33061,node3:33062,proxysql:33063'loose-group_replication_bootstrap_group=offloose-group_replication_single_primary_mode=offloose-group_replication_enforce_update_everywhere_checks=true

 

 

重要参数详解:(一定要铭记在心那么些)

    Above is the multi-primary mode of MGR,There're something diffrerent such as "certify" and "consensus" in the picture.The consensus based on paxos make sure the consistencies between the masters.but it's still a shared-nothing replication the same as the classical replication. 

after_sync(since MySQL 5.7):

MGCRUISER一定要敞开GTID作用gtid_mode = ON,enforce_gtid_consistency = ON

 

 

MG奥迪Q5在近期MySQL版本中,必供给设置binlog_checksum=none,并且binlog_format=row

    Notice,in multi-primary mode,all ther masters can execute transactions and commit independently,if there's a confilct(which always happens in the certification procedure),for example,they want to update the same row of one table,only one master who has the earlier golobal transaction sequence will get the privilege to finish the operation(what seems like first commit win principle).

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名爵ENVISION需求多源复制功效,所以需求将主从库之间的音讯记录到表中。设置master_info_repository = TABLE和relay_log_info_repository = TABLE

 

    

MGKoleos中开启主键消息征集功用:transaction_write_set_extraction= XXHASH64

Summary:

    In the picture above,the t1 transaction shouldn't be lost because of the master merely commits to the storage engine after receive the ACK signal from slave.In spite of master may crash before receiving ACK signal,no transaction will lose as the master hasn't commit at all.Meanwhile,the t2 transaction also get consistent query here.

MGLAND中把该参数group_replication_single_primary_mode关闭指标是搭建多主格局。尽管搭建单主模型,保持暗中同意参数就可以。

  • Be compared with MHA & PXC,MGR is the newest supplement in MySQL high availability family.
  • There're still few case using MGR to implement in product system nowadays.
  • MySQL Servers don't need to failover but the application does.
  • The practical usage of MGR is together with some middleware product such as ProxySQL.

 

MG昂科拉中要求设置组的名字,该group_replication_group_name是透过select uuid()来变化的。

 

    In order to improve the data consistency(since after_commit has avoidless deficiency),MySQL official enhances the semi-synchronous replication which can be called "loss-less semi-synchronous replication" in MySQL 5.7 by add after_sync mode in parameter "rpl_semi_sync_master_wait_point".

MG奥德赛前本地成员的地址由该参数group_replication_local_address决定,本例中当前节点是node2。后边的端口是各样节点都亟需叁个单身的tcp端口号,节点之间通过那几个端口号进行通讯。

 

MG中华V中别的成员的地方由那几个参数group_replication_group_seeds决定

    Caution,semi-synchronous replication may turn into asynchronous replication whenever the delay time of slave surpass the value which is specified in parameter "rpl_semi_sync_master_timeout"(default values is 10000 milliseconds).Why it is permitted?I'm afraid in order to consider the performance of master.Notwithstanding,you can also play a trick to prevent it from being converted over by set a infinite number in this parameter such as "10000000" or above.Especially in case that your product system is too important to not lose data.

MG陆风X8选拔多主情势时,须要让该参数group_replication_single_primary_mode=off(默许是单主情势)。

 

于此同有的时候间须求将该参数group_replication_enforce_update_everywhere_checks=true。目标是为了做多主形式限制检验。

    Further more,to configure semi-sychronous replication,you should implement the optional plugin component "rpl_semi_sync_master",which can be check by using command "show plugins;"

注:加载到参数文件之中,须求在各样参数的日前加loose。

 

此地再重申三个参数group_replication_auto_increment_increment。该参数代表自增属性,默许值为7。大家要保障每一种成员的该值一样,并且提议该参数的安装尽量比组内成员的个数大学一年级部分,方便早先时期集群的扩展。

Summary:

实战第6步:

  • Commonly,semi-sync replication is strongly recommended when implements MySQL replication nowadays(with gtid).
  • I utterly recommend to upgrade product system to MySQL 5.7 in order to use "after_sync" mode which can avoid data loss.
  • Be careful of specify an inappropriate value in parameter "rpl_semi_sync_master_timeout" which will cause converting semi-sync to async replication.

在192.168.56.101上运行第3个节点的MGCR-V集群服务。命令如下:

 

CHANGEMASTERTOMASTER_USER='repl', MASTER_PASSWORD='123456'FORCHANNEL'group_replication_recovery'

(MG翼虎必要该异步复制通道,完结新节点出席集群自动从其余节点复制数据的指标,不必要手工行业内部定从哪些节点复制,master_host和master_port新闻。都是机动实现)

SET GLOBAL group_replication_bootstrap_group = ON;

(试行开头化操作,唯有第五个节点要求这一步操作)

START GROUP_REPLICATION; 

启航成功之后,查看节点状态音信。命令如下

SELECT*FROMperformance_schema.replication_group_members;

原著链接:http://blog.51cto.com/sumongodb/2083286

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