Replication Tips & Tricks

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Presentation on replication tips and tricks given at the MySQL Connect 2012 conference.

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  • 1. Replication Tips & TricksMats Kindahlmats.kindahl@oracle.com 2Copyright 2012, Oracle and/or its affiliates. All rights reserved. Insert Information Protection Policy Classification from Slide 12

2. Program Agenda Replication setup and status checking Binary log analysis Crash-safe slaves Multi-source replication Slave fail-over using GTID3 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 3. About the PresentationThis presentation will introduce you to some replicationfeatures and also briefly show tips and tricks on how towork with replication. The focus is on short ideas andeach item does not go deeper into details.4 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 4. Replication Architecture Master Slave5 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 5. Reading Slave StatusUnderstanding the fields of SHOW SLAVE STATUS I/O Thread Status SQL Thread Status Slave_IO_Running Slave_SQL_Running Last_IO_Errno Last_SQL_Errno Last_IO_Error Last_SQL_Error Last_IO_Error_Timestamp Last_SQL_Error_Timestamp Master being replicated from Master_Host Master_Port6 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 6. Reading Slave StatusUnderstanding the fields of SHOW SLAVE STATUS Next event to execute in master log coordinates Relay_Master_Log_File + Exec_Master_Log_Pos Next event to execute in relay log coordinatesRelay_Log_File + Relay_Log_Pos Next event to read from masterMaster_Log_File + Read_Master_Log_Pos7 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 7. Reading the Binary LogDecoding the binary log Use mysqlbinlog--hexdumpShow hex dump of event as comment--start-position Start dumping at a position--stop-position Stop dumping after this position# at 275175 =373 16 10#120927 23:11:58 server id 3 end_log_pos 373# Position TimestampTypeMaster IDSizeMaster PosFlags#113 1e c1 64 50 0203 00 00 00 62 00 00 00 75 01 00 00 00 00 Little-endian Query8 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 8. Reading the Binary LogDecoding the binary log# at 275#120927 23:11:58 server id 3 end_log_pos 373# Position TimestampTypeMaster IDSizeMaster Pos Flags#113 1e c1 64 50 0203 00 00 00 62 00 00 00 75 01 00 0000 00#126 c5 03 00 00 00 00 00 00 04 00 00 1a 00 00 00 00 |................|#136 00 00 01 00 00 00 00 00 00 00 00 06 03 73 74 64 |.............std|#146 04 21 00 21 00 08 00 74 65 73 74 00 69 6e 73 65 |.......test.inse|#156 72 74 20 69 6e 74 6f 20 74 32 20 76 61 6c 75 65 |rt.into.t2.value|#166 73 20 28 31 2c 27 74 65 73 74 69 6e 67 27 29 |s..1..testing..|#Querythread_id=965exec_time=0 error_code=0SET TIMESTAMP=1348780318/*!*/;insert into t2 values (1,testing)/*!*/;9 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 9. Reading the Binary LogDecode row events Use mysqlbinlog--verboseDecode row events into pseudo-SQL # at 849 # at 893 #120928 15:19:24 server id 3end_log_pos 893 Table_map: `test`.`t2` mapped to number 48 #120928 15:19:24 server id 3end_log_pos 941 Write_rows: table id 48 flags: STMT_END_F BINLOG3KNlUBMDAAAALAAAAH0DAAAAADAAAAAAAAEABHRlc3QAAnQyAAIDDwIoAAM= 3KNlUBcDAAAAMAAAAK0DAAAAADAAAAAAAAEAAv/8AwAAAA1yb3dzIGFyZSBjb29s /*!*/;10Copyright 2012, Oracle and/or its affiliates. All rights reserved. 10. Reading the Binary LogDecode row events Use mysqlbinlog--verboseDecode row events into pseudo-SQL # at 849 # at 893 #120928 15:19:24 server id 3end_log_pos 893 Table_map: `test`.`t2` mapped to number 48 #120928 15:19:24 server id 3end_log_pos 941 Write_rows: table id 48 flags: STMT_END_F BINLOG3KNlUBMDAAAALAAAAH0DAAAAADAAAAAAAAEABHRlc3QAAnQyAAIDDwIoAAM= 3KNlUBcDAAAAMAAAAK0DAAAAADAAAAAAAAEAAv/8AwAAAA1yb3dzIGFyZSBjb29s /*!*/; ### INSERT INTO test.t2 ### SET ### @1=3 ### @2=rows are cool11Copyright 2012, Oracle and/or its affiliates. All rights reserved. 11. Cloning a Slave Creating a slave image1. Stop the slave2. Write down where slave has stoppedSHOW SLAVE STATUSRelay_Master_Log_File + Exec_Master_Log_Pos3. Backup slavemysqldump slow but safePhysical file copy fast but you need to shut down the server12 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 12. Cloning a Slave Setting up the new slave4. Restore backup on new slave5. Direct the slave to the masterCHANGE MASTERMaster_Host + Master_PortRelay_Master_Log_File + Exec_Master_Log_Pos6. Start slaveSTART SLAVE13 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 13. Cloning a Slave The easy way using MySQL UtilitiesUsing mysqldbcopy mysqldbcopyreplication=slave locking=snapshot source=root:pass@master.example.com destination=root:pass@slave.example.com database...14 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 14. Cloning a Slave The easy way using MySQL UtilitiesUsing mysqldbcopy mysqldbcopyreplication=slave locking=lockall source=root:pass@master.example.com destination=root:pass@slave.example.com database...15 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 15. Point in time recoveryUse mysqlbinlog --to-datetimeStop reading when reaching dateExample mysqlbinlog --read-from-remote-server e --host=master -uroot --position=192ar! --to-datetime=2009-04-11 12:36:56 psingam reas st master-bin.00002[2-4] | enc mysql -uroot --host=slavetim lly i:a ing icr n ot on W a onmnot16 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 16. Using Relay ServersRelieve master server by creating relay slavesJust keep binary logsDo not store data in tablesUse BLACKHOLE engine--log-slave-updatesSET STORAGE_ENGINE = BLACKHOLEALTER TABLE table ENGINE = BLACKHOLE17 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 17. Using Relay Servers replicate-wild-do-table-wild=*.%_east replicate-wild-do-table-wild=*.%_westFiltering replication streamFiltering done on relay serversreplicatewild*tableWork with cross-database queries18 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 18. Write Your Own Library Write your own utility libraryCreate a utility library to easier work with replicationCommon functions to manage replication:Start/stop slaveChange masterFetch master positionFetch slave execute/read positionFetch master host information19 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 19. Write Your Own Library Basic functions using Bourne shell #Usage:mysql_execsocketsql...#Usage:stop_slavesocket[thread] mysql_exec(){stop_slave(){ sock=$1mysql_exec$1STOPSLAVE$2 shift1} mysqlurootverticalbatch skipcolumnnames#Usage:start_slavesocket[thread] socket="$sock"start_slave(){ exec"$*"mysql_exec$1STARTSLAVE$2 }}20 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 20. Write Your Own Library Basic functions using Bourne shell #Usage:change_mastersocket[host[port[file[pos]]]] change_master(){ host=${2:+MASTER_HOST=$2} port=${3:+,MASTER_PORT=$3} file=${4:+,MASTER_LOG_FILE=$4} pos=${5:+,MASTER_LOG_POS=$5} mysql_exec$1CHANGEMASTERTO$host$port$file$pos } #Usage:fetch_master_possocket fetch_master_pos(){ mysql_exec$1SHOWMASTERSTATUS| grep$1.savepos }24 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 24. Round-Robin Replication A version using Bourne Shell restore_and_start () { cnt=1 socket="/var/run/mysqld/$1.sock" while true cat $1.savepos | { do read host stop_and_save mysqld.$cnt read port cnt=`expr $cnt % 5 + 1` read file restore_and_start mysqld.$cnt read possleep 60 change_master $socket done$host $port $file $pos start_slave $socket } }25 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 25. Crash-safe Slaves Keeping replication information in sync with data FILE TABLETraditional ReplicationPosition stored in fileUpdate after transactionCrash can lose updateTransactional Replication Repository location FILE or TABLEPositions stored in table master_info_repositoryUpdate part of transactionrelay_log_info_repositoryCrash-safe26 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 26. Crash-safe Slaves Steps to set up crash-safe slavesDirect server to use table-based repositoryDefaults to FILE master_info_repository=TABLE relay_log_info_repository=TABLEEnsure that a transactional engine is usedInnoDB default since 5.6.6Before 5.6.6: set the storage engine ALTERTABLEslave_master_infoENGINE=InnoDB ALTERTABLEslave_relay_log_infoENGINE=InnoDB27 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 27. Round-Robin Replication A version using pure SQL CREATE TABLE my_masters (CREATE TABLE current_master ( idx INT PRIMARY KEY, idx INT host CHAR(50) NOT NULL,) ENGINE=InnoDB port INT NOT NULL DEFAULT 3306, log_file CHAR(50), log_pos LONG, UNIQUE INDEX (host,port,user) ) ENGINE=InnoDB CREATE PROCEDURE save_position() BEGINDECLARE l_idx INT UNSIGNED;UPDATE my_masters AS mi, mysql.slave_relay_log_info AS rli SET mi.log_pos = rli.master_log_pos, mi.log_file = rli.master_log_name WHERE idx = (SELECT idx FROM current_master); END28 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 28. Round-Robin Replication In pure SQLCREATE PROCEDURE fetch_next_master(OUT p_host CHAR(50), OUT p_port INT UNSIGNED, OUT p_file CHAR(50), OUT p_pos BIGINT)BEGIN DECLARE l_next_idx INT DEFAULT 1; SELECT idx INTO l_next_idx FROM my_masters Select next index,WHERE idx > (SELECT idx FROM current_master)if there is oneORDER BY idx LIMIT 1; SELECT idx INTO l_next_idx FROM my_mastersSelect the first index, ifWHERE idx >= l_next_idx ORDER BY idx LIMIT 1; there were no next index UPDATE current_master SET idx = l_next_idx; SELECT host, port, log_file, log_pos Fetch master info using INTO p_host, p_port, p_file, p_pos FROM my_masters WHERE idx = l_next_idx;the indexEND29 Copyright 2012, Oracle and/or its affiliates. All rights reserved. 29. Round-Robin Replication In pure SQLCREATE EVENT multi_source ON SCHEDULE EVERY 10 SECOND DOBEGIN DECLARE l_host CHAR(50); DECLARE l_port INT UN