MySQL Server Performance Tuning 101

Transcription

1 MySQL Server Performance Tuning 101 Ligaya Turmelle Principal Technical Support Engineer - MySQL Copyright 2015, 2014, Oracle and/or its affiliates. All rights reserved. 1

2 Safe Harbor Statement The following is intended to outline our general product It is intended for purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or func@onality, and should not be relied upon in making purchasing decisions. The development, release, of any features or func@onality described for Oracle s products remains at the sole discre@on of Oracle. 2

3 Laying the Founda;on Copyright 2014, 2015, Oracle and/or its affiliates. All rights reserved. 3

4 MySQL in a Nutshell Worlds most popular open source database M of LAMP Main site: mysql.com Developer Zone: dev.mysql.com OR mysql.org - Downloads and Labs - Manuals and Bugs - Forums and Worklogs 4

5 Step 0 General - No easy answers - Benchmark and test - Under allocate 5

6 Step 0 The Server - OS - Network - Filesystem 6

7 Step 0 MySQL Server - Op@mize the queries - Database schema 7

8 MySQL and Memory Global Per Connection 2 Server Start Large Values As Needed Small Values Allocated Once Allocated 0-N Times Global Memory + (Max Connections * Per Connection Buffers) 8

9 Current SeKngs mysql> SHOW GLOBAL VARIABLES; mysql> SELECT * FROM INFORMATION_SCHEMA.GL OBAL_VARIABLES; (5.7) mysql> SELECT * FROM PERFORMANCE_SCHEMA.GL OBAL_VARIABLES; mysql> SHOW GLOBAL VARIABLES; Variable_name Value auto_increment_increment 1 auto_increment_offset 1 autocommit ON automatic_sp_privileges ON back_log 80 basedir /Users/ligaya/ mysql_installs/mysql osx10.7-x86_64 big_tables OFF bind_address * binlog_cache_size binlog_checksum CRC32 binlog_direct_non_transactional_updates OFF binlog_format STATEMENT binlog_max_flush_queue_time 0 binlog_order_commits ON binlog_row_image FULL binlog_rows_query_log_events OFF binlog_stmt_cache_size bulk_insert_buffer_size character_set_client latin1 character_set_connection latin1 9

10 Current SeKngs my.cnf / my.ini # The following options will be passed to all MySQL clients [client] #password! = your_password port!! = 5626 socket!! = /tmp/mysql sock # The MySQL server [mysqld] #################### # specific to this test instance port!! = 5626 socket!! = /tmp/mysql sock log-error = /mysql /data/error.log basedir = /mysql datadir = /mysql /data safe-user-create server-id! = 1 #################### 10

11 Anything Else? RAM? Dedicated? 32/64 bit OS/MySQL? Workload? Storage Engines? 11

12 Current Status mysql> SHOW GLOBAL STATUS; mysql> SELECT * FROM INFORMATION_SCHEMA.GL OBAL_STATUS; (5.7) mysql> SELECT * FROM PERFORMANCE_SCHEMA.GL OBAL_STATUS; mysql> SHOW GLOBAL STATUS; Variable_name Value Aborted_clients 9363 Aborted_connects Binlog_cache_disk_use Binlog_cache_use Bytes_received Bytes_sent Com_admin_commands Com_assign_to_keycache 0 Com_alter_db 0 Com_alter_db_upgrade 0 Com_alter_event 0 Com_alter_function 0 Com_alter_procedure 0 Com_alter_server 0 Com_alter_table 37 Com_alter_tablespace 0 Com_analyze 0 Com_begin Com_binlog 0 12

13 Danger Math Ahead! Copyright 2015, Oracle and/or its affiliates. All rights reserved. 13

14 Finding the Delta Uptime - seconds -Ex: sec = ~ hrs = ~ 95.5 days Find your rate of change 14

15 Example 15

16 Time to Start Copyright 2014, 2015, Oracle and/or its affiliates. All rights reserved. 16

17 Areas We Will Cover General InnoDB MyISAM - Older systems

18 Areas We Will Cover Query Cache - Older systems Thread and Table Cache Session Level

19 Areas We Will Cover General InnoDB MyISAM - Older systems

20 COM_* Counters Each command Used to calculate the Delta Com_select Com_set_option Com_signal 0 Com_show_authors 0 Com_show_binlog_events 0 Com_show_binlogs Com_show_charsets 1 Com_show_collations 39 Com_show_contributors 0 Com_show_create_db 3 Com_show_create_event 0 Com_show_create_func 1120 Com_show_create_proc Com_show_create_table Com_show_create_trigger 0 Com_show_databases 435 Com_show_engine_logs 0 Com_show_engine_mutex 0 Com_show_engine_status Com_show_events 0 Com_show_errors 0 Com_show_fields Com_show_function_status 29 20

21 Et Al. and 21

22 Et Al. and Queries and 22

23 Et Al. and Queries and Slow_queries 23

24 Et Al. and Queries and Slow_queries Handler_read_* 24

25 max_connecuons Max permiled concurrent Value affects memory usage higher values (200+) - thread pooling - connec@on pooling 25

26 skip_name_resolve Do not resolve host name for client Removes DNS lookups - faster connec@ons - no need to worry about slow DNS Drawback: Use only IP addresses 26

27 sql_mode Changed a lot over the years and versions 20+ modes available Dictates how the system operates - Defines SQL syntax supported and what data valida@on checks are performed - Examples: Mode: STRICT_TRANS_TABLES : If values can not be inserted as given into a transac@onal table, abort the statement. Mode: NO_ZERO_DATE : Whether server permits as a valid date Mode: NO_ENGINE_SUBSTITUTION : Controls automa@c subs@tu@on of the default storage engine when CREATE TABLE or ALTER TABLE uses a storage engine that is disabled or not compiled in 27

28 Areas We Will Cover General InnoDB MyISAM - Older systems

29 How is InnoDB doing? Efficiency - Innodb_buffer_pool_reads_requests - Innodb_buffer_pool_reads Formula: 1 - (Innodb_buffer_pool_read / Innodb_buffer_pool_read_requests) = buffer pool hit ratio 29

30 innodb_buffer_pool_size Global Dynamic (5.7.5) Caches data and indexes Larger values reduces IO Self- contained Max value - Manual: 80% ; Personal: 60-70% 30

31 innodb_buffer_pool_instances 5.5+ Problem: for the buffer pool resources For systems with large GB buffer pools Total buffer pool size divided between this many instances Each instance - Manages its own resources - Has its own mutex 31

32 innodb_log_file_size Size of file on disk Larger the file, the less checkpoint Size for each log file Max combined log file size - 4G < = 512G Larger the log file longer 32

33 innodb_log_buffer_size Global Buffer for to log files on disk Large Write heavy? - Yes - increasing can help with IO Default: 8M 33

34 innodb_file_per_table.ibd files Default: Off <= > On Easier to reclaim space TRUNCATE for a table is faster Can monitor table size on the file system Can store specific tables on different storage devices (5.6) Transportable tablespaces - (5.7) Par@@oned tables supported 34

35 innodb_flushlog_at_trx_commit Performance Vs Durability 1 - Default - ACID Compliant 2 - Can lose up to 1 second of transac@ons - InnoDB log buffer wrilen to log file at each commit - flushed to disk once per second 0 - Can lose up to 1 second of transac@ons - InnoDB log buffer wrilen to log file once per second and then flushed to disk 35

36 innodb_flush_method For Unix and Linux Method used to flush data and log files to disk Dependent on hardware Default: fdatasync O_DIRECT recommended if you use a hardware RAID controller 36

37 innodb_numa_interleave New sewng (5.6.27) Only relevant to those on NUMA architecture - shell> dmesg grep -i numa Enables NUMA interleave memory policy for buffer pool Not available in generic tarball or Windows from MSI installer Public bug reports associated with NUMA: 57241, &

38 innodb_flush_neighbors 5.6+ When flushing a page, flush other dirty pages in same extent Default: 1 - Use for spinning disks Change to 0 - Use for SSDs - Have both SSD and spinning disk 38

39 Areas We Will Cover General InnoDB Basics MyISAM - Older systems

40 How is MyISAM doing? Space - Key_blocks_unused Formula: key_buffer_size - (Key_blocks_unused * key_cache_block_size) = amount actually in use - Key_blocks_used High water mark 40

41 How is MyISAM doing? Efficiency - Key_read_requests - Key_reads Formula: Key_reads / Key_read_requests = key cache miss rate 41

42 How is MyISAM doing? Locking - Table_locks_immediate - Table_locks_waited 42

43 key_buffer_size AKA key cache Global Index blocks only 25% - maybe 43

44 Areas We Will Cover Query Cache - Older systems Threads and Table Cache Session Level

45 QC Data Into Info Hit rate - Higher the beler Invalida@ng queries - Bigger the diff - the beler Formula: Qcache_hits / (Qcache_hits + Com_select) = Query Cache Hit Rate Comparison: Qcache_inserts << Com_select 45

46 query_cache_size Global Allocated all at once Default: disabled Default size: 0 < => 1M Max: 100MB 46

47 query_cache_type Global - but can be session 3 op@ons - 0 Off - 1 On - 2 On Demand Default: 1 < => 0 47

48 Gotchas! 48

49 Areas We Will Cover Query Cache - Older systems Threads and Table Caches Session Level

50 Threads Threads == Thread Cache - Threads_cached - Threads_connected - Threads_created Formula: Threads_created / Connections = Thread cache miss rate 50

51 thread_cache_size Global but grows as needed Number to be cached needed May increase performance with lots of new - Or may not Formula: ((Threads_created / Connections) * 100) = Thread cache efficiency 51

52 table_open_cache table_cache <= > table_open_cache Global but expands as needed Number of open tables for all - higher more you need Watch Opened_tables 52

53 table_open_cache_instances Reduces between sessions Default 1 - Consider 8 or 16 on 16+ core systems

54 table_definiuon_cache Global but expands as needed Number of table (.frm file) to hold Large number of tables large cache = speed up table opening InnoDB - Soz limit for open table instances in data dic@onary - Soz limit for number of InnoDB file per table tablespaces open at 5.1+ Autosizes >=

55 Areas We Will Cover Query Cache - Older systems Threads and Table Cache Session Level

56 Temporary Tables max_heap_table_size Dynamic Set maximum size of all MEMORY tables Dynamic tmp_table_size In-memory - MEMORY table max size of internal inmemory temp tables Becomes on-disk table 56

57 sort_buffer_size Dynamic Doing a sort - allocates a buffer this size Helps with ORDER BY and/or GROUP BY 256K is a decent star@ng place Watch Sort_merge_passes 57

58 join_buffer_size Use with care Use for - Plain index scan - Range index scan - Joins that do not use indexes - full table scan One buffer for each full join between tables 58

59 QuesUons? Copyright 2014, 2015, Oracle and/or its affiliates. All rights reserved. 59

60 MySQL Server Performance Tuning 101 Ligaya Turmelle Principal Technical Support Engineer - MySQL hlps://legacy.joind.in/16770 Copyright 2015, 2014, Oracle and/or its affiliates. All rights reserved. 60

61 Copyright 2014, Oracle and/or its affiliates. All rights reserved.