MySQL&Server& PerformanceTuning101 - Khan...

Copyright © 2015, Oracle and/or its affiliates. All rights reserved. |

MySQL Server Performance Tuning 101

Ligaya TurmellePrincipal Technical Support Engineer -‐ [email protected]@lig

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | 1Sunday, October 16, 16


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The following is intended to outline our general product direc@on. It is intended for informa@on 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, and @ming of any features or func@onality described for Oracle’s products remains at the sole discre@on of Oracle.

2Sunday, October 16, 16

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. |Copyright © 2015, Oracle and/or its affiliates. All rights reserved. |

Laying the Founda;on



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



Step 0

• General-‐ No easy answers-‐ Benchmark and test

-‐ Under allocate



Step 0

• The Server- OS

- Network

- Filesystem



Step 0

• MySQL Server-‐ Op@mize the queries

-‐ Database schema



MySQL and Memory

2

8

Global Per Connection

Server Start As Needed

Large Values Small Values

Allocated Once Allocated 0-N Times

Global Memory + (Max Connections * Per Connection Buffers)

Sunday, October 16, 16


Current SeKngs

• mysql> SHOW GLOBAL VARIABLES;

• mysql> SELECT * FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES;

• (5.7) mysql> SELECT * FROM PERFORMANCE_SCHEMA.GLOBAL_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-5.6.16-osx10.7-x86_64 | big_tables | OFF | bind_address | * | binlog_cache_size | 32768 | 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 | 32768 | bulk_insert_buffer_size | 8388608 | character_set_client | latin1 | character_set_connection | latin1



Current SeKngs

• my.cnf / my.ini

# The following options will be passed to all MySQL clients

[client]#password! = your_passwordport! ! = 5626socket!! = /tmp/mysql.5.6.26.sock

# The MySQL server[mysqld]##################### specific to this test instanceport! ! = 5626socket!! = /tmp/mysql.5.6.26.socklog-error = /mysql-5.6.26/data/error.logbasedir = /mysql-5.6.26datadir = /mysql-5.6.26/datasafe-user-createserver-id! = 1####################



Anything Else?

• RAM?

• Dedicated?• 32/64 bit OS/MySQL?

• Workload?

• Storage Engines?



Current Status

• mysql> SHOW GLOBAL STATUS;

• mysql> SELECT * FROM INFORMATION_SCHEMA.GLOBAL_STATUS;

• (5.7) mysql> SELECT * FROM PERFORMANCE_SCHEMA.GLOBAL_STATUS;

mysql> SHOW GLOBAL STATUS;+--------------------------------------+---------------+| Variable_name | Value |+--------------------------------------+---------------+| Aborted_clients | 9363 || Aborted_connects | 15925 || Binlog_cache_disk_use | 15684 || Binlog_cache_use | 272758675 || Bytes_received | 1219816389366 || Bytes_sent | 5227022143540 || Com_admin_commands | 12803263 || 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 | 33025640 || Com_binlog | 0 |



Danger Math Ahead!



Finding the Delta

• Uptime - seconds-Ex: 8249391 sec = ~2291.5 hrs = ~ 95.5 days

• Find your rate of change



Example



Time to Start



Areas We Will Cover

• General

• InnoDB

• MyISAM -‐ Older systems

1

2

3



Areas We Will Cover

• Query Cache -‐ Older systems

• Thread and Table Cache

• Session Level

5

4

6



Areas We Will Cover

• General

• InnoDB


1

2

3



COM_*

• Counters• Each command

• Used to calculate the Delta

| Com_select | 1530076294 || Com_set_option | 18004985 || Com_signal | 0 || Com_show_authors | 0 || Com_show_binlog_events | 0 || Com_show_binlogs | 27498 || 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 | 14499 || Com_show_create_table | 183538 || Com_show_create_trigger | 0 || Com_show_databases | 435 || Com_show_engine_logs | 0 || Com_show_engine_mutex | 0 || Com_show_engine_status | 1180106 || Com_show_events | 0 || Com_show_errors | 0 || Com_show_fields | 2915144 || Com_show_function_status | 29 |



Et Al.

• Connec@ons and Max_used_connec@ons



Et Al.


• Queries and Ques@ons



Et Al.


• Queries and Ques@ons• Slow_queries



Et Al.


• Queries and Ques@ons• Slow_queries• Handler_read_*



max_connecUons

• Max permiled concurrent connec@ons.• Value affects memory usage• higher values (200+) consider/inves@gate

-‐ thread pooling-‐ connec@on pooling



skip_name_resolve

• Do not resolve host name for client connec@ons• Removes DNS lookups

-‐ faster connec@ons-‐ no need to worry about slow DNS

• Drawback: Use only IP addresses



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 ‘0000-‐00-‐00’ 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



Areas We Will Cover

• General

• InnoDB


1

2

3

1

2



How is InnoDB doing?

• Efficiency-Innodb_buffer_pool_reads_requests

-Innodb_buffer_pool_reads

29

Formula:1 - (Innodb_buffer_pool_read / Innodb_buffer_pool_read_requests)

= buffer pool hit ratio



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%



innodb_buffer_pool_instances

• 5.5+• Problem: conten@on for the buffer pool resources• For systems with large mul@-‐GB buffer pools• Total buffer pool size divided between this many instances• Each instance

-‐ Manages its own resources-‐ Has its own mutex



innodb_log_file_size

• Size of file on disk• Larger the file, the less checkpoint ac@vity• Size for each log file• Max combined log file size

-‐ 4G < 5.5-‐ 5.6 = 512G

• Larger the log file ➯ longer recovery @me



innodb_log_buffer_size

• Global• Buffer for wri@ng to log files on disk• Large transac@ons? Write heavy?

-‐ Yes -‐ increasing can help with IO• Default: 8M



innodb_file_per_table

• .ibd files• Default: Off <= 5.6.5 > 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



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



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



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

37

Public bug reports associated with NUMA: 57241, 72811 & 78953



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



Areas We Will Cover

• General

• InnoDB Basics


1

2

3

1

2



How is MyISAM doing?

• Space-‐ Key_blocks_unused

-‐ Key_blocks_used• High water mark

40

Formula:key_buffer_size - (Key_blocks_unused * key_cache_block_size)

= amount actually in use




• Efficiency-‐ Key_read_requests-‐ Key_reads

41

Formula:Key_reads / Key_read_requests = key cache miss rate




• Locking-‐ Table_locks_immediate-‐ Table_locks_waited



key_buffer_size

• AKA key cache• Global• Index blocks only• 25% -‐ maybe



Areas We Will Cover


• Threads and Table Cache

• Session Level

5

4

6



QC Data Into Info

• Hit rate-‐ Higher the beler

• Invalida@ng queries-‐ Bigger the diff -‐ the beler

45

Formula:Qcache_hits / (Qcache_hits + Com_select) =

Query Cache Hit Rate

Comparison:Qcache_inserts << Com_select



query_cache_size

• Global• Allocated all at once• Default: disabled• Default size: 0 < 5.6.8 => 1M• Max: 100MB



query_cache_type

• Global -‐ but can be session• 3 op@ons

-‐ 0 “Off”-‐ 1 “On”-‐ 2 “On Demand”

• Default: 1 < 5.6.8 => 0



Gotchas!



Areas We Will Cover


• Threads and Table Caches

• Session Level

5

4

6



Threads

• Threads == Connec@on• Thread Cache

-‐ Threads_cached-‐ Threads_connected-‐ Threads_created

50

Formula:Threads_created / Connections = Thread cache miss rate



thread_cache_size

• Global but grows as needed• Number to be cached un@l needed• May increase performance with lots of new connec@ons

-‐ Or may not

51

Formula:100 - ((Threads_created / Connections) * 100) =

Thread cache efficiency



table_open_cache

• table_cache <= 5.1.3 > table_open_cache• Global but expands as needed• Number of open tables for all connec@ons

-‐ higher max_connec@ons, more you need• Watch Opened_tables



table_open_cache_instances

• Reduces conten@on between sessions• Default 1

-‐ Consider 8 or 16 on 16+ core systems• 5.6+



table_definiUon_cache

• Global but expands as needed• Number of table defini@ons (.frm file) to hold• Large number of tables ➯large defini@on 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 1 @me

• 5.1+• Autosizes >=5.6.8



Areas We Will Cover


• Threads and Table Cache

• Session Level

5

4

6



Temporary Tables

56

max_heap_table_size

• Dynamic• Set maximum size of all

MEMORY tables

tmp_table_size

• Dynamic• In-memory - MEMORY table• max size of internal in-

memory temp tables• Becomes on-disk table



sort_buffer_size

57

• 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



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



QuesUons?



MySQL Server Performance Tuning 101

Ligaya TurmellePrincipal Technical Support Engineer -‐ [email protected]@lig

hlps://legacy.joind.in/16770

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. | 60Sunday, October 16, 16

https://legacy.joind.in/16770

https://legacy.joind.in/16770



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