MySQL Cluster performance best practices

MySQL Cluster : Delivering Breakthrough Performance26th July 2012 Andrew Morgan Mat Keep Senior Product Manager – MySQL HA Senior Product Manager – MySQL HA andrew.morgan@oracle.com mat.keep@oracle.com clusterdb.com

The presentation 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 2012 Oracle Corporation - 26th July 2012 2

Session Agenda •  Introduction to MySQL Cluster •  Where does MySQL Cluster fit? •  Benchmarks •  WHILE (cluster.measurePerformance() < target) { cluster.optimize(); } •  Boosting performance •  Scaling out •  Further resourcesCopyright 2012 Oracle Corporation - 26th July 2012 3

MySQL Cluster – Users & Applications Extreme Scalability, Availability and Affordability •  Web •  High volume OLTP •  eCommerce •  On-Line Gaming •  Digital Marketing •  User Profile Management •  Session Management & Caching •  Content Management •  Telecoms •  Service Delivery Platforms •  VAS: VoIP, IPTV & VoD •  Mobile Content Delivery •  Mobile Payments •  LTE Access http://www.mysql.com/customers/cluster/Copyright 2012 Oracle Corporation - 26th July 2012 4

MySQL Cluster Architecture JPA REST Application Nodes Node Group 1 Node Group 2 F1 F2 Node 1 Node 3 Cluster Cluster Mgmt F3 F4 Mgmt F3 F4 Node 4 Node 2 F1 F2 Data NodesCopyright 2012 Oracle Corporation - 26th July 2012 5

When to Consider MySQL Cluster l  What are the consequences of downtime or failing to meet performance requirements? l  How much effort and $ is spent in developing and managing HA in your applications? l  Are you considering sharding your database to scale write performance? How does that impact your application and developers? l  Do your services need to be real-time? l  Will your services have unpredictable scalability demands, especially for writes ? l  Do you want the flexibility to manage your data with more than just SQL ?Copyright 2012 Oracle Corporation - 26th July 2012 6

Where would I not Use MySQL Cluster? •  “Hot” data sets >3TB •  Replicate cold data to InnoDB •  Long running transactions •  Large rows, without using BLOBs •  Foreign Keys •  Check out MySQL Cluster 7.3 Early Access: http://labs.mysql.com/ •  Many full table scans •  Geo-Spatial indexes •  In these scenarios; InnoDB storage engine would be the right choice MySQL Cluster Evaluation Guide http://mysql.com/why-mysql/white-papers/mysql_cluster_eval_guide.phpCopyright 2012 Oracle Corporation - 26th July 2012 7

General Design Considerations •  MySQL Cluster is designed for –  Short transactions –  Many parallel transactions •  Utilize Simple access patterns to fetch data –  Use efficient scans and batching interfaces •  Analyze what your most typical use cases are –  optimize for those Overall design goal Minimize network roundtrips for your most important requests!Copyright 2012 Oracle Corporation - 26th July 2012 8

Comparing MySQL Cluster Performance 8x Higher Performance per Node 20 18 Reads per Second (Millions) 16 14 12 10 8 6 4 2 0 MySQL Cluster 7.1 MySQL Cluster 7.2 •  1 Billion+ Reads per Minute, 8 node Intel Xeon cluster •  Multi-Threaded Data Node Extensions •  NoSQL C++ API, flexaSynch benchmarkCopyright 2012 Oracle Corporation - 26th July 2012 11

1.2 Billion UPDATEs per Minute 25 Millions of UPDATEs per Second 20 15 10 5 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 MySQL Cluster Data Nodes •  30 x Intel E5-2600 Intel Servers •  NoSQL C++ API, flexaSynch benchmark •  ACID Transactions, with Synchronous ReplicationCopyright 2012 Oracle Corporation - 26th July 2012 12

WHILE (cluster.measurePerformance() < target) •  Don’t optimize for the sake of it •  Wastes effort •  Introduces unnecessary compromises/complications •  Forget about database benchmarks •  You care about the end-to-end performance of your application on your database •  If possible drive your application to drive the database •  Measurements need to be based on representative traffic •  Measurements need to be repeatable •  Easily see impact of each optimizationCopyright 2012 Oracle Corporation - 26th July 2012 13

Where has the time gone? •  Enable the slow query log –  set global slow_query_log=1; –  set global long_query_time=3; //3 seconds –  set global log_queries_not_using_indexes=1; –  Slow queries will be written in the slow query log: mysql> show global variables like slow_query_log_file; +---------------------+------------------------------+ | Variable_name | Value | +---------------------+------------------------------+ | slow_query_log_file | /data1/mysql/mysqld-slow.log | +---------------------+------------------------------+ •  Queries will be written in plain textCopyright 2012 Oracle Corporation - 26th July 2012 14

Simple database traffic generation create.sql: CREATE TABLE sub_name (sub_id INT NOT NULL PRIMARY KEY, name VARCHAR(30)) engine=ndb; CREATE TABLE sub_age (sub_id INT NOT NULL PRIMARY KEY, age INT) engine=ndb; INSERT INTO sub_name VALUES (1,Bill),(2,Fred),(3,Bill), (4,Jane),(5,Andrew),(6,Anne),(7,Juliette),(8,Awen), (9,Leo),(10,Bill); INSERT INTO sub_age VALUES (1,40),(2,23),(3,33),(4,19),(5,21), (6,50),(7,31),(8,65),(9,18),(10,101); query.sql: SELECT sub_age.age FROM sub_name, sub_age WHERE sub_name.name=Bill AND sub_name.sub_id=sub_age.sub_id;Copyright 2012 Oracle Corporation - 26th July 2012 16

Simple database traffic generation shell> mysqlslap --concurrency=5 -- iterations=100 --query=query.sql -- create=create.sql Benchmark Average number of seconds to run all queries: 0.132 seconds Minimum number of seconds to run all queries: 0.037 seconds Maximum number of seconds to run all queries: 0.268 seconds Number of clients running queries: 5 Average number of queries per client: 1Copyright 2012 Oracle Corporation - 26th July 2012 17

What on Earth is it doing? EXPLAIN is your friend mysql> EXPLAIN <query>; mysql> EXPLAN PARTITIONS <query>; mysql> EXPLAIN EXTENDED <query>; mysql> SHOW WARNINGS;Copyright 2012 Oracle Corporation - 26th July 2012 18

Boosting Performance • ANALYZE TABLE •  Connection pools •  Access patterns •  Multi-threaded data •  AQL (fast JOINs) nodes •  Distribution aware •  NoSQL APIs •  Batching •  Hardware •  Schema •  More tipsCopyright 2012 Oracle Corporation - 26th July 2012 19

Before you do anything else, ANALYZE! •  New for MySQL Cluster 7.2 •  Lets the MySQL optimizer figure out how to best use indexes etc. •  Instantly speed up queries by many times mysql> ANALYZE TABLE <tab-name>; •  Repeat after changing schema, adding/removing indexes or making major data changes •  Only needs running on one mysqld in the clusterCopyright 2012 Oracle Corporation - 26th July 2012 20

Access patterns •  Primary key reads/writes -> O(1) •  Independent of database size and number of nodes •  Index searched -> O(log n) •  n = number of tuples •  BLOBs are stored in second table -> take longer to access •  JOINs massively faster in MySQL Cluster 7.3 •  Partition pruning •  By allowing a query to be satisfied with a single data node, reduce resource consumption -> greater throughput •  If result sets not large, will also reduce latencyCopyright 2012 Oracle Corporation - 26th July 2012 21

Adaptive Query Localization Scaling Distributed Joins 70x More Performance •  Perform Complex Queries mysqld across Shards •  JOINs pushed down to data nodes A Data Nodes •  Executed in parallel Q •  Returns single result set to MySQL L •  Opens Up New Use-Cases •  Real-time analytics •  Recommendations engines mysqld •  Analyze click-streams Data Nodes DON’T COMPROMISE FUNCTIONALITY TO SCALE-OUT !!Copyright 2012 Oracle Corporation - 26th July 2012 22

Web-Based CMS Query Execution Time Seconds 70x More 100 Performance 90 80 70 87.23 seconds 60 50 40 30 20 10 1.26 seconds 0 MySQL Cluster 7.1 MySQL Cluster 7.2Must Analyze tables for best resultsmysql> ANALYZE TABLE <tab-name>;Copyright 2012 Oracle Corporation - 26th July 2012 24

AQL – How to Use it•  Activated when ndb_join_pushdown is on (default)•  Rules for a Join to be pushed down: 1.  Joined columns use identical types 2.  No reference to BLOB or TEXT columns 3.  No explicit lock 4.  Child tables in the Join must be accessed using one of the ref, eq_ref, or const 5.  Tables not explicitly partitioned by [LINEAR] HASH, LIST, or RANGE 6.  Query plan doesn’t select ‘Using join buffer 7.  If root of Join is an eq_ref or const, child tables must be joined by eq_ref•  Run ANALYZE TABLE <tab-name> on each table once•  Use EXPLAIN to see what components are being pushed down: •  Extra: Child of d in pushed join@1 •  EXPLAIN EXTENDED <query>;SHOW WARNINGS;Copyright 2012 Oracle Corporation - 26th July 2012 26

Distribution Aware AppsSELECT SUM(population) FROM towns •  Partition selected using hash onWHERE country=“UK”; Partition Key Partition Key Primary Key •  Primary Key by default town country population •  User can override in table definition Maidenhead UK 78000 •  MySQL Server (or NDB API) will Paris France 2193031 attempt to send transaction to the Boston UK 58124 correct data node Boston USA 617594 •  If all data for the transaction are inSELECT SUM(population) FROM towns the same partition, less messaging -WHERE town=“Boston”; > faster Partition Key •  Aim to have all rows for high-running Primary Key queries in same partition town country population Maidenhead UK 78000 Paris France 2193031 Boston UK 58124 Boston USA 617594Copyright 2012 Oracle Corporation - 26th July 2012 27

Distribution Aware – Multiple Tables Partition Key Primary Key sub_id age gender •  Extend partition awareness over 19724 25 male multiple tables 84539 43 female •  Same rule – aim to have all data for 19724 16 female instance of high running 74574 21 female transactions in the same partition Partition Key Primary Key ALTER TABLE service_ids service sub_id svc_id PARTITION BY KEY(sub_id); twitter 19724 76325732 twitter 84539 67324782 facebook 19724 83753984 EXPLAIN PARTITIONS <query>; facebook 73642 87324793Copyright 2012 Oracle Corporation - 26th July 2012 28

Validate if “partition pruning” is working mysql> SHOW GLOBAL STATUS LIKE ndb_pruned_scan_count; +-----------------------+-------+ | Variable_name | Value | +-----------------------+-------+ | Ndb_pruned_scan_count | 12 | +-----------------------+-------+ mysql> SELECT * FROM services WHERE sub_id=1; +--------+--------------+--------------+ | sub_id | service_name | service_parm | +--------+--------------+--------------+ | 1 | IM | 878 | | 1 | ssh | 666 | | 1 | Video | 654 | +--------+--------------+--------------+ mysql> SHOW GLOBAL STATUS LIKE ndb_pruned_scan_count; +-----------------------+-------+ | Variable_name | Value | +-----------------------+-------+ | Ndb_pruned_scan_count | 13 | +-----------------------+-------+Copyright 2012 Oracle Corporation - 26th July 2012 29

Batching•  MySQL Cluster allows batching on •  Inserts, index scans (when not part of a JOIN), PK reads, PK deletes, and PK (most) updates. •  Batching means that one network round trip is used to read/modify a number of records → less ping-pong! •  If you can batch - do it!•  Example – Insert 1M records •  No batching: •  INSERT INTO t1(data) VALUES (<data>); •  765 seconds to insert 1M records •  Batching (batches of 16): •  INSERT INTO t1(<columns>) VALUES (<data>), (<data>)... •  50 seconds to insert 1M recordsCopyright 2012 Oracle Corporation - 26th July 2012 30

Batching, more examplesSELECT * FROM t1 WHERE userid=1 AND serviceid IN (1,2,3,4,5,7,8,9,10);SET transaction_allow_batching=1; //must be set on the connectionBEGIN; INSERT INTO t1 ....; INSERT INTO t2 ....; INSERT INTO t3 ....; INSERT INTO t4 ....; DELETE FROM t5 ....; UPDATE t1 SET value=new value WHERE id=1;COMMIT;Copyright 2012 Oracle Corporation - 26th July 2012 31

Optimizing schema - denormalization userid voip_data userid bb_data SELECT * FROM bb,voip WHERE 1 <data> 1 <data> 2 <data> 2 <data> bb.userid=voip.userid AND 3 <data> 3 <data> bb.userid=1; 4 <data> 4 <data> voip bb userid voip_data bb_data 1 <data> <data> mysql> SELECT * FROM 2 <data> <data> voip_bb WHERE userid=1; 3 <data> <data> 4 <data> <data> 1.7x improvement voip_bbCopyright 2012 Oracle Corporation - 26th July 2012 32

Connection Pools •  Network hops increase latency (e.g. Compared with InnoDB read of cached data) App thread App thread App thread App thread App thread App thread •  Increase throughput by sending in lots of parallel operations •  Multiple client connections (sessions) to each MySQL Server mysqld mysqld •  Multiple MySQL Servers NDB API NDB API •  Connection pooling between MySQL Servers and data nodes •  Set ndb-cluster-connection-pool > 1 in my.cnf •  Ensure enough [api] sections inData Nodes config.ini •  Don’t assign hostnames!Copyright 2012 Oracle Corporation - 26th July 2012 33

Multi-threaded data nodes •  Scaling out on commodity hardware is the standard Application Nodes way to increase performance •  Add more data nodes and Node 3 API nodes as required •  MySQL Cluster 7.2Node 1 increases the ability to also scale-up each data node •  Increases maximum number of utilised threads from 8 to 59 Node 2 Node 4 Node Group 1 Node Group 2 Copyright 2012 Oracle Corporation - 26th July 2012 34

Multi-threaded data nodes •  Threads: •  ldm: 1,2,4,8 or 12 Local Application Nodes Query Handler threads •  tc: typically ldm/4 Transaction Coordinator threads •  send: ~2-3 SendData Node 1 recv send main threads •  recv: ~2-4 Receive threads •  main: 1 Main thread •  rep: 1 Replication tc ldm rep io thread •  io: 1 I/O thread Copyright 2012 Oracle Corporation - 26th July 2012 35

Multi-threaded data nodes •  Applies to ntbdmtd only •  Configure through either: •  MaxNoOfExecutionThreads •  Single value for number of threads •  System will allocate these threads to blocks in a reasonable way •  ThreadConfig •  Specify explicitly how many threads for each block type •  Lock threads to CPUs for further performance gains •  Threadconfig=main={cpubind=0},ldm= {count=4,cpubind=1,2,5,6},io= {count=2,cpubind=3,4}Copyright 2012 Oracle Corporation - 26th July 2012 36

Multi-threaded data nodes – starting point for ThreadConfig 24 threads 32 threads 40 threads 48 thread ldm 8 12 16 16 tc 4 6 8 12 recv 3 3 4 5 send 3 3 4 4 rep 1 1 1 1 Note that some threads are left for other data node blocks as well as the OSCopyright 2012 Oracle Corporation - 26th July 2012 37

NoSQL APIs Clients JDBC / ODBC PHP / PERL Native memcached HTTP/REST Python / Ruby NDB API Data Nodes Mix •  SQL: Complex, relational queries & •  Memcached: Key-Value web services Match •  Java: Enterprise Apps •  NDB API: Real-time servicesCopyright 2012 Oracle Corporation - 26th July 2012 38

Hardware •  High bandwidth, low latency network •  Turn off firewalls if you can •  Use multiple disks •  Checkpoints •  Log files •  Table spaces •  SSDs •  Biggest benefit for Table spaces •  Refer to MySQL Cluster Evaluation Guide for more detailsCopyright 2012 Oracle Corporation - 26th July 2012 39

MySQL Query Cache •  Dont enable the Query Cache! •  It is very expensive to invalidate over multiple MySQL servers •  A write on one server will force the others to purge their cache. •  If you have tables that are read only (or change very seldom): my.cnf: query_cache_size=1000000 query_cache_type=2 (ON DEMAND) mysql> SELECT SQL_CACHE <cols> .. FROM table; •  SQL_CACHE tells (demands) MySQL to cache the results from this SELECT •  This can be good for STATIC dataCopyright 2012 Oracle Corporation - 26th July 2012 40

Non-Durable tables •  Some types of tables account for a lot of WRITEs, but do not need to be recovered (e.g, Session tables) •  Unnecessary to persist such tables - no REDO LOGs or CHECKPOINTs •  Create these tables as NO LOGGING tables: mysql> set ndb_table_no_logging=1; mysql> create table session_table (..) engine=ndb; mysql> set ndb_table_no_logging=0; •  After system restart table will be there, but empty!Copyright 2012 Oracle Corporation - 26th July 2012 41

More optimisation tips •  When using auto-increment columns, increase ndb- autoincrement-prefetch-sz •  Set RedoBuffer=32-64M •  Disk-based tables: •  Increase UNDO_BUFFER for write-intensive apps •  Increase DiskIOThreadPool •  Increase DiskPageBufferMemory for better caching in the data nodes; Monitor effectiveness using NDBINFO / MEM • FragmentLogFileSize=256M • NoOfFragmentLogFiles= 6 x DataMemory (in MB) / (4x 256MB) •  Use OPTIMIZE TABLE and perform rolling restarts if memory fragmentation is an issueCopyright 2012 Oracle Corporation - 26th July 2012 42

Scaling out with MySQL Cluster Manager client mysqld mysqld ndb_mgmd ndb_mgmd agent agent 192.168.0.10 192.168.0.11 ndbd ndbd ndbd ndbd agent agent 192.168.0.12 192.168.0.13Copyright 2012 Oracle Corporation - 26th July 2012 43

Scaling out with MySQL Cluster Manager client mysqld mysqld mysqld mysqld ndb_mgmd ndb_mgmd agent agent 192.168.0.10 192.168.0.11 ndbd ndbd ndbd ndbd ndbd ndbd ndbd ndbd agent agent agent agent 192.168.0.12 192.168.0.13 192.168.0.14 192.168.0.15Copyright 2012 Oracle Corporation - 26th July 2012 44

Scaling out with MySQL Cluster Managermcm> add hosts --hosts=192.168.0.14,192.168.0.15 mysite;mcm> add package --basedir=/usr/local/mysql_7_0_9 --hosts=192.168.0.14,192.168.0.15 7.0.9;mcm> add process -- processhosts=mysqld@192.168.0.10,mysqld@192.168.0. 11,ndbd@192.168.0.14,ndbd@192.168.0.15,ndbd@192.16 8.0.14,ndbd@192.168.0.15 -s port:mysqld: 52=3307,port:mysqld:53=3307 mycluster;mcm> start process --added mycluster;mysql> ALTER ONLINE TABLE <table-name> REORGANIZE PARTITION;mysql> OPTIMIZE TABLE <table-name>;Copyright 2012 Oracle Corporation - 26th July 2012 45

Download MySQL Cluster Today!http://www.mysql.com/downloads/cluster/#downloads

Further resources•  MySQL Cluster Performance white paper: http://www.mysql.com/why-mysql/white-papers/ mysql_wp_cluster_performance.php•  MySQL Cluster Forum: http://forums.mysql.com/list.php?25•  MySQL Cluster Evaluation guide: http://www.mysql.com/why-mysql/white-papers/ mysql_cluster_eval_guide.php•  MySQL Cluster in Web-Scale Architectures: http://www.mysql.com/why-mysql/white-papers/ mysql_cluster_eval_guide.php

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MySQL Cluster performance best practices

by Mat Keep on Aug 08, 2012

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