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MySQL High Availability with Replication New Features

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The session was presented at open source India 2014 (http://osidays.com/osidays/) by Shivji (me) and Manish Kumar. It talks of the new features in MySQL-5.7 Replication. It covered work on
1) performance enhancements in MySQL Replication
2) Usability improvements
3) More flexibility to provide more options to our users so
they can chose what is best for their application.
4) Semisynchronous and MySQL Group Replication

At then end, there are a lot of links to the blogs written on these features by the MySQL Replication engineers.

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MySQL High Availability with Replication New Features

  1. 1. Open Source India 2014 MySQL High Availability with Replication New Features Shivji Kumar Jha (shivji.jha@oracle.com) Manish Kumar (manish.4.kumar@oracle.com) Software Developer, MySQL Replication Team 2 Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  2. 2. Safe Harbor Statement The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  3. 3. Program Agenda Background Performance Usability Flexibility Consistency Extras Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 0 1 2 3 4 5
  4. 4. Program Agenda Background Performance Usability Flexibility Consistency Extras Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 0 1 2 3 4 5
  5. 5. Background: Replication Components relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Sender thread Receiver thread Applier Threads Network
  6. 6. Background: What is Replication Used For? S Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Read scale-out M S S S M write clients read clients read clients write clients More reads? More slaves!
  7. 7. What about write scale-out? More writes? More Masters? M? M M? write clients write clients M? MySQL Fabric helps sharding your data with MySQL... Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  8. 8. Redundancy: If master crashes, promote slave to master Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | C B A Background: What is Replication Used For? C B CraAsh C B A B is the new master Uh Oh! Whew!
  9. 9. Background: What is Replication Used For? On-line Backup and Reporting Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | M S write clients  business intelligent client apps  reporting client apps  big queries client apps
  10. 10. Background: What is Replication Used For? CB CA AB Image from www.ginkgomaps.com Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  11. 11. Program Agenda Background Performance Usability Flexibility Consistency Extras Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 1 2 3 4 5 6
  12. 12. Performance — Higher Master Throughput.  Improved concurrency between Sender and user threads,  More Sender thread enhancements... — Higher Slave Throughout.  MySQL- 5.7.2: Multi-Threaded Slave (MTS) Timestamp based Applier.  MySQL Labs: Enhanced MTS Timestamp based Applier.  Options to Fine Tune Binlog Group Commit and Multi-Threaded Applier Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  13. 13. Improved concurrency b/w Sender and user threads relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  14. 14. Improved concurrency b/w Sender and user threads Concurrent reads by the sender thread with ongoing writes from user threads. — Sender thread does not block user sessions more than necessary. — Higher throughput for both sender threads and user sessions. Sender Thread Reads Binary Log User Thread Writes to Binary Log Sender Thread Reads Binary Log User Thread Writes to Binary Log Time Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | pre 5.7.2 5.7.2+
  15. 15. More Sender Thread Enhancements relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  16. 16. More Sender Thread Enhancements  Send buffer is not allocated and freed every time an event is sent.  When sender threads require larger send buffer → buffer grows as needed.  When buffer is larger than needed→ buffer shrinks dynamically.  Together with the sender thread enhancements released on MySQL 5.7.2: — increase master scalability; — Master, with dump threads attached, copes better with peak loads; — Separate semisync ACK receiver thread (details later!) Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  17. 17. More Sender Thread Enhancements  Ad hoc microbenchmark using mysqlslap  1M queries, concurrency=200, commit=1  N slaves attached (fake slaves using remote mysqlbinlogs)  48 cores HT / 512 GB RAM / HDD 0 1 5 10 20 30 40 50 100 16000 14000 12000 10000 8000 6000 4000 2000  Small number of slaves: no difference between 5.6 and 5.7.  Larger number of slaves: 5.7 is able to sustain the same throughput while 5.6 is not. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 0 Master's Throughput MySQL 5.6.16 MySQL 5.7.4 Number of Slaves QpS
  18. 18. This was the case when we released MySQL 5.6 GA.  Up to 5x more throughput with 10 sysbench schemas.  Changes to each schema applied and committed independently by worker threads (both in SBR and RBR). 0 1 2 3 4 5 6 10 24 Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 300 250 200 150 100 50 0 Slave Throughput Number Worker Threads QpS Higher Slave Throughput (MySQL-5.6)
  19. 19. Higher Slave Throughput (MySQL-5.6) “It's the bee's knees! We've been using it at VividCortex in production and it works great.” – Baron Schwartz, CEO, VividCortex https://vividcortex.com/blog/2014/03/17/multi-threaded-replication-in-mysql/ Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  20. 20. Higher Slave Throughput (MySQL-5.7) relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  21. 21. Higher Slave Throughput Timestamp based Multi-threaded Slave (MTS) Applier ● Leverage parallelization information obtained from the execution on the master. ● Transactions that prepare on the same “version” of the database, are assigned the same timestamp. ● Meanwhile, at the slave: ● Transactions with the same timestamp can be executed in parallel; ● Concurrent transactions commit independently, thus no waiting involved. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  22. 22. Higher Slave Throughput  Supports statement-based or row-based formats.  Scheduling policy controlled through: mysql> SET slave_parallel_type= [logical_clock|database] — logical_clock - means schedule based on the prepare timestamp. — database - the scheduling policy from 5.6 (concurrency control done per database).  Work to improve slave scalability continues, does not stop here. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  23. 23. relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads Enhanced Scheduling Policy (MTS)
  24. 24. Enhanced Scheduling Policy (MTS) Sysbench / oltp test / 48 clients / 10M rows SSD / 48 core HT / 512 GB RAM GTIDs / Crash-safe Numbers from mysql-5.7.5-labs-preview UPDATED TO BE 0 4 16 50 200 Up to 6X performance improvement vs single threaded slave without any changes to the application Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 Transactions per Second (TPS) TPS while replaying 300 seconds of accumulated load from the master. Baseline 100 clients – 5.7.5-labs 200 clients – 5.7.5-labs Number of Worker Threads Transactions Per Second
  25. 25. BGC tuning options – MTS Enhancers relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  26. 26. BGC tuning options – MTS Enhancers Sysbench / oltp test / 48 clients / 10M rows SSD / 48 core HT / 512 GB RAM GTIDs / Crash-safe Numbers from mysql-5.7.4-labs-mts Transactions Per Second small commit delay large commit delay 0 5 10 15 20 25 30 35 40 45 50 4500 4000 3500 3000 2500 2000 1500 1000 500 0 Number of Slave Worker Threads TPS Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  27. 27. BGC tuning options – MTS Enhancers By tuning BGC on the master, we get more parallelism on the slave. Tuning means more transactions preparing together (no magic formula – highly dependent on hardware and workload). Ongoing work on improving MTS and on the analysis of experimental results. Transactions Per Second small commit delay large commit delay 0 5 10 15 20 25 30 35 40 45 50 4500 4000 3500 3000 2500 2000 1500 1000 500 0 Number of Slave Worker Threads TPS  6X slave throughput – large commit delay  3X slave throughput – small commit delay Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  28. 28. Program Agenda Background Performance Usability Flexibility Consistency Extras Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 1 2 3 4 5 6
  29. 29. Better Replication Monitoring relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  30. 30. Better Replication Monitoring Performance Schema Replication Tables ● Access monitoring information through an SQL interface. ● Write stored functions or procedures with input from replication internals. ● Logically unrelated information into different places. ● Flexible and easier to extend and adapt as new feature get into the server. ● More user friendly names identifying the monitoring fields. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  31. 31. Better Replication Monitoring Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Connection Configuration Connection Status Execution Configuration Execution Status Slave Status Applier / Coordinator Status Workers Status
  32. 32. Program Agenda Background Performance Usability Flexibility Consistency Extras Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 1 2 3 4 5 6
  33. 33. Semi-sync Replication – Wait for Multiple ACKs relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  34. 34. Semi-sync Replication – Wait for Multiple ACKs  Master does not commit transaction until it receives N ACKs from N slaves.  Dynamically settable: mysql> SET GLOBAL rpl_semi_sync_master_wait_for_slave_count= N Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Master T1: COMMIT Slave 2 relaylog ACK Time Slave 1 relaylog ACK T1: COMMIT succeeds mysql> SET GLOBAL rpl_semi_sync_master_wait_for_slave_count= 2
  35. 35. relay log Storing GTIDs In a Table Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... B Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads gtid_executed gtid_executed
  36. 36. Storing GTIDs In a Table Use Cases  Slaves can use GTIDs with binary logs disabled. — Slaves that are never candidates to become a master can still use GTIDs for auto positioning.  GTIDs are more resilient to unexpected deletion of binary logs. — If the DBA decides to delete all binlogs but the most recent one, GTID history is still preserved. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  37. 37. Storing GTIDs In a Table Mechanics  GTIDs are saved into a mysql system table. CREATE TABLE gtid_executed( source_uuid CHAR(36) NOT NULL, interval_start BIGINT NOT NULL, interval_end BIGINT NOT NULL, PRIMARY KEY(source_uuid, interval_start) Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | );
  38. 38. Storing GTIDs In a Table Mechanics  If binary log is enabled, gtids are first stored on the binary log and then copied to the table on binlog rotation or shutdown.  If binary log is disabled, gtids are stored in the table on commit. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  39. 39. Preserve Commit Order (MTS) relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  40. 40. Preserve Commit Order (MTS)  Multi-threaded Applier May be Instructed to Preserve Commit Order. — Applier Threads will commit in the same order transactions appear in the relay log. — Order is enforced at the expense of performance degradation. — This is controllable through the new global option/variable: --slave-preserve-commit-order. Default is FALSE. mysql> SET GLOBAL slave_preserve_commit_order= [TRUE|FALSE] Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  41. 41. Redirect to new Master without interrupting the Applier relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  42. 42. Redirect to new Master without interrupting the Applier Change master to B from A without stopping the applier threads. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | C B A C B CraAsh C B A B is the new master Uh Oh! Whew!
  43. 43. Redirect to new Master without interrupting the Applier Change master to M2 from M1 without stopping the applier threads. Uh Oh! Whew! Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | C B A C B CraAsh C B A DBA did not need C to stop applying its relay log to change C's master from A to B.
  44. 44. Redirect to new Master without interrupting the Applier  More “onlineness” during fail-over: mysql> STOP SLAVE IO_TRHEAD; mysql> CHANGE MASTER TO MASTER_HOST='master2', …; mysql> START SLAVE IO_THREAD;  Stopping, changing master and restarting the receiver thread is all done while the applier thread is running.  Change applier properties while the receiver thread is working: mysql> STOP SLAVE SQL_TRHEAD; mysql> CHANGE MASTER TO MASTER_DELAY=3600, …; mysql> START SLAVE SQL_THREAD; Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  45. 45. Dynamic Slave Replication Filters relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  46. 46. Dynamic Slave Replication Filters Change Slave's Replication Filters dynamically. — No need to stop and restart slave for establishing new replication filtering rules. — All slave filters are supported. mysql> CHANGE REPLICATION FILTER REPLICATE_DO_DB= (db1, db2) Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  47. 47. Multi-Source Replication M M Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | S Slave can have more than one master. Feature preview based on 5.7 is available on labs.mysql.com . M M The need for gathering data in a central server:  Integrated backup;  Complex queries for analytics purposes;
  48. 48. Multi-Source Replication  A server (slave) can replicate from multiple sources (masters).  Multiple channels (channel: connection thread, relay log, applier threads) that can be stopped started individually.  Integrated with Multi-threaded Slave: each channel has its own multi-threaded applier set of threads.  Integrated with the new P_S tables. — replication_execute_status_by_coordinator shows multiple entries, one per channel/source applier. — replication_connection_status shows multiple entries, one per connection to different sources. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  49. 49. Multi-Source Replication  Integrated with GTIDs.  Integrated with crash-safe tables. — Progress state is stored in these tables for recoverability purposes.  Works with semisync replication. — Working on further improving the integration.  Virtually no limit on the number of sources (capped to 256, but can be changed if server binary is rebuilt).  Able to manage each source separately. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  50. 50. Program Agenda Background Performance Usability Flexibility Consistency Extras Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 0 1 2 3 4 5
  51. 51. Loss-less Semi-sync Replication relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads
  52. 52. Loss-less Semi-sync Replication  Master waits for slave's ACK before committing (as opposed to: master waits for slave's ACK after committing). — Therefore, concurrent transactions do not externalize changes while waiting for ACK.  Should a master fail, then any transaction that it may have externalized is also persisted on a slave.  User can choose between the original semisync behavior and the new one. mysql> SET rpl_semi_sync_master_wait_point= [AFTER_SYNC|AFTER_COMMIT] Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  53. 53. Loss-less Semi-sync Replication prepare commit Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Master Slave execute binlog relaylog T1: INSERT INTO t1 VALUES (1000) ACK Time T1 T2: SELECT * FROM t1; T2 empty set
  54. 54. Semi-sync Replication – ACK Receiver Thread relay log Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Insert... Insert... B binary log Insert... Insert... A binary log Client Network Sender thread Receiver thread Applier Threads ACK Receiver thread
  55. 55. Semi-sync Replication – ACK Receiver Thread  Consecutive transactions do not block each other while waiting for ACKs — Transaction t1 and t2 are sent immediately to the slave by the sender thread — ACKs are received only by a special thread — Transaction t2 does not include t1 round trip in its semisync overall latency  Thread starts when semisync is activated mysql> SET GLOBAL rpl_semi_master_enabled= ON  Thread stops when semisync is deactivated mysql> SET GLOBAL rpl_semi_master_enabled= ON Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  56. 56. Semi-sync Replication in MySQL 5.7 “Semi-sync in MySQL 5.7 looks like a great improvement. [...] With MySQL 5.7, I’d be much more apt to recommend semi-sync as an option than in previous releases. Thanks to Oracle for investing here.” – Jay Janssen, MySQL Consulting Manager, Percona Inc http://www.percona.com/blog/2014/05/27/semi-sync-replication-performance-mysql-5-7-4-dmr/ Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  57. 57. Introducing MySQL Group Replication  Multi-master update everywhere with conflict resolution.  Automatic distributed member recovery — When a server joins the group, it gets all the missing transactions before actually start serving requests. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  58. 58. Group-Based Replication Plugin M M M M M MySQL Server API Replication Plugin Group Comm. System (Corosync) Group Comm. System (Corosync) Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  59. 59. Group-Based Replication Plugin Update ... M M M M M Application issues an update. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  60. 60. Group-Based Replication Plugin M M M M M Replication Events Application issues an update. Master executes and multi/broadcasts the update to the other servers. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  61. 61. Group-Based Replication Plugin M M M M M Application issues an update. Master executes and multi/broadcasts the update to the other servers. Servers receive same transaction in the same order and check for conflicts. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  62. 62. Group-Based Replication Plugin M M M M M Application issues an update. Master executes and multi/broadcasts the update to the other servers. Servers receive same transaction in the same order and check for conflicts. All servers, independently, decide to commit the transaction – no conflicts. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  63. 63. Group-Based Replication Plugin Application issues an update. Master executes and multi/broadcasts the update to the other servers. Servers receive same transaction in the same order and check for conflicts. All servers, independently, decide to commit the transaction – no conflicts. Originating master replies to the application. M M M M M Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  64. 64. MySQL Group Replication: Use Cases ● Automatic group membership management and failure detection - No need for server fail-over ● No single point of failure - Automatic reconfiguration Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  65. 65. Under the hood ● Each server can belong to a group. ● The Group is identified by a name which is the Group UUID string, so group behaves like a single server. ● The Group UUID is used to log transactions. ● Whenever a server joins or leaves, it will start a new stable period in time on which servers can agree on distributed decisions. A special message called View Message is sent to each group member notifying that. ● Server join/leave can be issue manually or by scripts by DBA. ● Server leave can be caused also by node failures. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  66. 66. Under the hood  Current used group communication toolkit is Corosync. It provides: — Virtual synchrony guarantees for creating replicated state machines.  Replicated state machine simple definition: — If a set of processes with the same initial state receives the same set of deterministic messages at the same order, them will reach the same state.  All write operations are sent to all group members for certification.  Read operations are only local. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  67. 67. COMMIT dbv: 2 OK OK OK Certification - Positive Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | s1 s2 dbv: 1 UPDATE dbv: 2 s3 dbv: 2 COMMIT COMMIT cv: 1 1 >= 1 1 >= 1 1 >= 1 cv: 1 cv: 1 dbv: 1 dbv: 1 cv: 2 cv: 2 cv: 2 s ← server v ← snapshot version sn ← certifier sequence number (write set version)
  68. 68. T1: COMMIT dbv: 2 Certification - Negative OK OK T2: UPDATE cv: 2 OK KO KO KO Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | s1 s2 dbv: 1 T1: UPDATE dbv: 2 s3 dbv: 2 T1: COMMIT T1: COMMIT cv: 1 cv: 1 cv: 1 1 >= 1 1 >= 1 1 >= 1 cv: 2 cv: 2 1 >= 2 1 >= 2 1 >= 2 dbv: 1 dbv: 1 s ← server v ← snapshot version sn ← certifier sequence number (write set version)
  69. 69. Automated distributed member recovery Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | R1 R2 R3 R4 GCS R1 R2 R3 R4 R4 joins the group. GCS
  70. 70. Automated distributed member recovery Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | R1 R2 R3 R4 R1 is R4 Donor GCS R1 R2 R3 R4 GCS
  71. 71. Automated distributed member recovery Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | R1 R2 R3 R4 GCS R1 R2 R3 R4 GCS
  72. 72. Automated distributed member recovery Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | R1 R2 R3 R4 GCS R1 R2 R3 R4 R4 has caught up with the view! GCS
  73. 73. Automated distributed member recovery R1 R2 R3 R4 GCS Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | R1 R2 R3 R4 GCS Execute buffered transactions from the view.
  74. 74. PERFORMANCE SCHEMA TABLE – REPLICATION_NODE_STATUS ● Statistics regarding Applier and Certifier module. – REPLICATION_CONNECTION_NODES ● Information regarding different nodes in the group and its connection details – REPLICATION_CONNECTION_STATUS ● Extended table to give details about the group connection status. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  75. 75. Replication Monitoring: replication_node_status node1> SELECT * FROM performance_schema.replication_node_statusG *************************** 1. row *************************** GROUP_NAME: 8a84f397-aaa4-18df-89ab-c70aa9823561 NODE_ID: 2af09cb1-3e46-11e4-9e45-ecf4bb227f3b TRANSACTIONS_IN_QUEUE: 0 CERTIFIED_TRANSACTIONS: 12 POSITIVELY_CERTIFIED: 7 NEGATIVELY_CERTIFIED: 5 CERTIFICATION_DB_SIZE: 6 STABLE_SET: 8a84f397-aaa4-18df-89ab-c70aa9823561:1-7 LAST_CERTIFIED_TRANSACTION: 8a84f397-aaa4-18df-89ab-c70aa9823561:7 APPLIER_MODULE_STATUS: ON Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  76. 76. Replication Monitoring: replication_node_status node1> SELECT * FROM performance_schema.replication_connection_nodesG *************************** 1. row *************************** GROUP_NAME 8a94f357-aab4-11df-86ab-c80aa9429573 NODE_ID 597dbb72-3e2c-11e4-9d9d-ecf4bb227f3b NODE_HOST nightfury NODE_PORT 13000 NODE_STATE ONLINE *************************** 2. row *************************** GROUP_NAME 8a94f357-aab4-11df-86ab-c80aa9429573 NODE_ID 59efb8a1-3e2c-11e4-9d9d-ecf4bb227f3b NODE_HOST nightfury NODE_PORT 13001 NODE_STATE ONLINE *************************** 3. row *************************** GROUP_NAME 8a94f357-aab4-11df-86ab-c80aa9429573 NODE_ID 5a706f6b-3e2c-11e4-9d9d-ecf4bb227f3b NODE_HOST nightfury NODE_PORT 13002 NODE_STATE RECOVERING Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  77. 77. Replication Monitoring: replication_node_status node1> SELECT * FROM performance_schema.replication_connection_statusG *************************** 1. row *************************** GROUP_NAME: 8a94f357-aab4-11df-86ab-c80aa9429563 SOURCE_UUID: 8a94f357-aab4-11df-86ab-c80aa9429563 THREAD_ID: NULL SERVICE_STATE: ON COUNT_RECEIVED_HEARTBEATS: 0 LAST_HEARTBEAT_TIMESTAMP: 0000-00-00 00:00:00 RECEIVED_TRANSACTION_SET: LAST_ERROR_NUMBER: 0 LAST_ERROR_MESSAGE: LAST_ERROR_TIMESTAMP: 0000-00-00 00:00:00 TOTAL_MESSAGES_RECEIVED: 9 TOTAL_MESSAGES_SENT: 5 TOTAL_BYTES_RECEIVED: 1891 TOTAL_BYTES_SENT: 1065 LAST_MESSAGE_TIMESTAMP: 2014-09-23 09:20:26 MAX_MESSAGE_LENGTH: 358 MIN_MESSAGE_LENGTH: 51 VIEW_ID: 2 NUMBER_OF_NODES: 2 Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  78. 78.  Only transactional engines are supported (currently only InnoDB).  All tables must have primary key  GTID must be enabled.  Only deterministic DDL is allowed.  Optimistic execution: transactions may abort on COMMIT. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | Limitations
  79. 79. Program Agenda Background Performance Usability Flexibility Consistency Extras Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | 0 1 2 3 4 5
  80. 80. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. | References  Read a feature preview of MySQL Group replication on Luis' blog: http://mysqlhighavailability.com/mysql-group-replication-hello-world/  Read about how to get started with MySQL Group replication on Pedro's blog: http://mysqlhighavailability.com/getting-started-with-mysql-group-replication/  Read about Transaction life cycle in MySQL Group replication on Nuno's blog: http://mysqlhighavailability.com/mysql-group-replication-transaction-life-cycle-explained/  Read about Distributed recovery in MySQL Group Replication on Pedro's blog: http://mysqlhighavailability.com/distributed-recovery-behind-the-scenes/  Read about Monitoring for MySQL Group Replication on Manish's blog: http://mysqlhighavailability.com/mysql-group-replication-monitoring/  Read about Corosync and Group Communication details on Tiago's blog: http://mysqlhighavailability.com/group-communication-behind-the-scenes/ http://mysqlhighavailability.com/mysql-group-replication-a-small-corosync-guide/  Read about Testing of MySQL Group Replication on Manish's blog: http://mysqlhighavailability.com/mysql-group-replication-testing/
  81. 81. References: Read about the 5.7 DMRs Replication Features  Read more about P_S tables for replication on Shiv's blog: http://shivjijha.blogspot.com/2013/09/Monitoring-Replication-with-the-NEW-performance-schema-tables.html  Read more about Intra-Schema Multi-threaded Slave on Rohit's blog: http://geek.rohitkalhans.com/2013/09/enhancedMTS-deepdive.html ◾ Read more about Semisync enhancements on Libing's blog: http://my-replication-life.blogspot.com/2013/09/dump-thread-enhancement.html http://my-replication-life.blogspot.pt/2013/09/loss-less-semi-synchronous-replication.html Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  82. 82. References: Read about the 5.7 DMRs Replication Features ◾ Read more about mysqlbinlog idempotent mode on Rohit's blog: http://binlogtorelaylog.blogspot.com/2013/05/mysqlbinlog-idemmpotent-mode.html ◾ Read more about mysqlbinlog –rewrite-db option on Manish's blog: http://manishthe.blogspot.com/2013/05/introduction-with-wonderful-and-best.html Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  83. 83. References: Read about the 5.7 DMRs Replication Features  Read more on Dynamic Replication Filters on Venkat's blog: http://my-s-q-l.blogspot.com/2013/12/Making-MySQL-Slave-Replication-Filters-Dynamic.html  Read more on Semi-sync Multiple ACKs on Libing's blog: http://my-replication-life.blogspot.com/2013/12/enforced-semi-synchronous-replication.html  Read more on SSL options for mysqlbinlog on João's blog: http://jmysqlrep.blogspot.com/2013/12/mysql-57-mysqlbinlog-now-supports-ssl.html  Read more on Semisync ACK thread receiver on Libing's blog: http://my-replication-life.blogspot.com/2014/03/faster-semisync-replication.html Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  84. 84. References: Read about the 5.7 DMRs Replication Features  Read more on Flexible Change Master on Shiv's blog: http://work.shivjijha.com/2014/04/change-master-without-stopping-slave.html Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |
  85. 85. References: Read about the 5.7 DMRs Replication Features  Read more about Multi-source replication on Rith's blog: http://on-mysql-replication.blogspot.com/2013/09/feature-preview-mysql-multi-source-replication.html  Read a lot more on : mysqlhighavailability.com Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | Open Source India | Bangalore, India, 8th November, 2014. |

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