Capturing, Analyzing, and Optimizing Your SQL

Transcript

1. ODTUG – June 2010 Capturing, Analyzing & Optimizing your SQL Padraig O'Sullivan - http://posulliv.com/ Ronald Bradford - http://ronaldbradford.com/
2. ODTUG – June 2010 Capturing your SQL
3. ODTUG – June 2010 MySQL Provided Options Slow Query Log General Query Log Binary Log Connectors Processlist Engine status Status variables
4. ODTUG – June 2010 Other Techniques MySQL Proxy TCP/IP Capture Dtrace/SystemTap Application Management
5. ODTUG – June 2010 Slow Query Log Not enabled by default log-slow-queries = /path/to/file (5.0) slow_query_log/slow_query_log_file (5.1) Granularity of seconds Microsecond patch by percona Default slow time is 10 seconds long_query_time = 2 Log output to file or table (5.1) log_output = FILE | TABLE | BOTH http://dev.mysql.com/doc/refman/5.1/en/slow-query-log.html
6. ODTUG – June 2010 Slow Query Log Example # Time: 100518 19:34:31 # User@Host: user[db] @ localhost [] # Query_time: 4 Lock_time: 0 Rows_sent: 1155 Rows_examined: 1663671 select distinct visitorid from log where timestamp like '20100518%' and accountid!=1 and accountid!=37 and file not like '%admin%'; # Time: 100518 19:35:37 # User@Host: user[db] @ localhost [] # Query_time: 4 Lock_time: 0 Rows_sent: 6 Rows_examined: 1662525 select distinct accountid from log where timestamp>='20100518132033' and accountid NOT IN ('0','1','37','1635'); # Time: 100518 19:35:41 # User@Host: user[db] @ localhost [] # Query_time: 4 Lock_time: 0 Rows_sent: 2477 Rows_examined: 1664996 select timestamp, file from log where timestamp>='20100518000000' and timestamp<='end' and accountid!=1 and accountid!=37 order by timestamp desc; # Time: 100518 19:35:44 # User@Host: user[db] @ localhost [] # Query_time: 3 Lock_time: 0 Rows_sent: 1157 Rows_examined: 1663676 select distinct visitorid from log where timestamp like '20100518%' and accountid!=1 and accountid!=37 and file not like '%admin%';
7. ODTUG – June 2010 Slow Query Table Example mysql> select start_time, query_time, rows_sent, rows_examined, db, sql_text ­> from mysql.slow_log; +­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | start_time | query_time | rows_sent | rows_examined | db | sql_text | +­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | 2010­06­14 13:43:37 | 00:03:45 | 1 | 31290045 | drupal | select count(*) from search_index | +­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ 1 row in set (0.00 sec) mysql>
8. ODTUG – June 2010 General Query Log Not enabled by default log = /path/to/file general_log/general_log_file (5.1) Log output to file or table (5.1) log_output = FILE | TABLE | BOTH Never use in production Ideal for development, unit testing environments http://dev.mysql.com/doc/refman/5.1/en/query-log.html
9. ODTUG – June 2010 General Query Log Example 26 Query SELECT * FROM wp_users WHERE user_login = 'xxxx' 26 Query SELECT meta_key, meta_value FROM wp_usermeta WHERE user_id = 2 26 Query SELECT option_value FROM wp_options WHERE option_name = 'sidebars_widgets' LIMIT 1 26 Query SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts WHERE 1=1 AND wp_posts.post_type = 'post' AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private') ORDER BY wp_posts.post_date DESC LIMIT 0, 10 26 Query SELECT FOUND_ROWS() 26 Query SELECT t.*, tt.*, tr.object_id FROM wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON tt.term_id = t.term_id INNER JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ('category', 'post_tag') AND tr.object_id IN (2849, 2842, 2836, 2824, 2812, 2680, 2813, 2800, 2770, 2784) ORDER BY t.name ASC 26 Query SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (2849,2842,2836,2824,2812,2680,2813,2800,2770,2784) Output using Wordpress
10. ODTUG – June 2010 General Query Log Example (2) Framework new connection 23 Connect user@host 23 Query SELECT 1 23 Query SET NAMES utf8 23 Query SET character_set_results = NULL 23 Query SHOW VARIABLES 23 Query SHOW COLLATION 23 Query SET autocommit=1 23 Query SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED 23 Query SET autocommit=0
11. ODTUG – June 2010 General Query Log Example (3) Finding framework overhead ROLLBACK after every SELECT SELECT 1 – connection ping test 23 Query select count(*) from collection where account_name = 'xxx' and user_id = '313' 23 Query rollback 23 Query select 1 23 Query select count(*) from collection where account_name = 'xxx' and user_id = '346' 23 Query rollback 23 Query select 1 23 Query select name,user_id,date_format(`register_time`,'%Y%m%d%H%i%S') as createTime from account where name = 'xxx' and user_id = '346' and `status` = '1' 23 Query rollback 23 Query select 1 23 Query select max(mdate) from received where account_name = 'xxx' And user_id = '346' order by mdate desc 23 Query rollback
12. ODTUG – June 2010 Binary Log Not enabled by default log-bin = /path/to/file expire_log_days = 5 View with mysqlbinlog http://dev.mysql.com/doc/refman/5.1/en/binary-log.html
13. ODTUG – June 2010 Binary Log Example # at 2461 #100604 10:49:43 server id 1 end_log_pos 2632 Query thread_id=6 exec_time=0 error_code=0 use blog/*!*/; SET TIMESTAMP=1275662983/*!*/; UPDATE `wp_postmeta` SET `meta_value` = '1275662983' WHERE `meta_key` = '_edit_lock' AND `post_id` = 2849 /*!*/; # at 21107 #100604 10:58:49 server id 1 end_log_pos 21469 Query thread_id=62 exec_time=0 error_code=0 use monitoringmysql/*!*/; SET TIMESTAMP=1275663529/*!*/; SET @@session.time_zone='SYSTEM'/*!*/; INSERT INTO wp_redirection_logs (url,sent_to,created,agent,redirection_id,ip,referrer,module_id,group_id) VALUES ('/mysql­monitoring/dbtuna',NULL,NOW(),'Mozilla/5.0 (compatible; Yahoo! Slurp/3.0; http ://help.yahoo.com/help/us/ysearch/slurp)',NULL, '67.195.114.227', NULL, 3, NULL) /*!*/; mysqlbinlog /path/to/log-bin.000000
14. ODTUG – June 2010 Connector/J logSlowQueries slowQueryThresholdMillis SlowQueryThresholdNanos http://dev.mysql.com/doc/refman/5.1/en/connector-j-reference-configuration-properties.html
15. ODTUG – June 2010 Processlist Current connection/thread No filtering options Ideal for locking http://dev.mysql.com/doc/refman/5.1/en/show-processlist.html mysql> SHOW [FULL] PROCESSLIST $ mysqladmin [­v] processlist mysql> SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST (5.1))
16. ODTUG – June 2010 Processlist Example mysql [localhost] {root} ((none)) > show processlist; +­­­­­­­+­­­­­­+­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­ +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ ­­­­­+ | Id | User | Host | db | Command | Time | State | Info | +­­­­­­­+­­­­­­+­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­ +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ ­­­­­+ | 7 | root | localhost | NULL | Query | 0 | NULL | show processlist | | 20017 | root | localhost | oltp | Query | 0 | creating table | create table bench1 (a int NOT NULL,i int,s char(10),primary key (a)) | | 20020 | root | localhost | oltp | Query | 1 | copy to tmp table | ALTER TABLE bench ADD i919 integer,ADD i920 integer,ADD i921 integer,ADD i922 integer,ADD i923 | +­­­­­­­+­­­­­­+­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­ +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ ­­­­­+ 3 rows in set (0.00 sec)
17. ODTUG – June 2010 Processlist Example (2) | Id | User | Host | db | Command | Time | State | Info | 2692 | app_usr | db:44376 | db1 | Query | 3 | Sending data | SELECT ... | 2805 | app_usr | db:44703 | db1 | Query | 0 | statistics | SELECT ... FOR UPDATE | 2829 | app_usr | db:44812 | db1 | Query | 0 | init | UPDATE ... | 2845 | app_usr | db:44866 | db1 | Sleep | 2 | | NULL | 2846 | app_usr | db:44866 | db1 | Sleep | 2 | | NULL | 2915 | app_usr | db:56751 | db1 | Query | 0 | Updating | UPDATE ... | 2847 | app_usr | db:44868 | db1 | Query | 0 | query end | SELECT * FROM ... | 2928 | app_usr | db:56792 | db1 | Query | 0 | logging slow query | INSERT INTO ...
18. ODTUG – June 2010 Engine Status Provides engine specific information Vendor implemented InnoDB Running threads Last deadlock Last foreign key error Other engine types include NDB, PBXT, TOKUDB
19. ODTUG – June 2010 Engine Status mysql> SHOW ENGINE INNODB STATUS; http://dev.mysql.com/doc/refman/5.1/en/show-engine.html
20. ODTUG – June 2010 Engine Status Example ­­­­­­­­­­­­ TRANSACTIONS ­­­­­­­­­­­­ Trx id counter 0 480206585 Purge done for trx's n:o < 0 480205682 undo n:o < 0 0 History list length 5 LIST OF TRANSACTIONS FOR EACH SESSION: ­­­TRANSACTION 0 0, not started, process no 27230, OS thread id 1182685536 MySQL thread id 427, query id 123563 10.8.160.241 dba SHOW ENGINE INNODB STATUS ­­­TRANSACTION 0 0, not started, process no 27230, OS thread id 1169639776 MySQL thread id 44, query id 123445 10.8.160.241 dba ­­­TRANSACTION 0 480206305, ACTIVE 67 sec, process no 27230, OS thread id 1192270176 mysql tables in use 1, locked 1 1 lock struct(s), heap size 368, 0 row lock(s), undo log entries 1 MySQL thread id 370, query id 123171 10.120.229.37 user query end INSERT INTO `table` .... ­­­TRANSACTION 0 480206290, ACTIVE 70 sec, process no 27230, OS thread id 1178159456 mysql tables in use 1, locked 1 1 lock struct(s), heap size 368, 0 row lock(s), undo log entries 1 MySQL thread id 372, query id 123150 10.120.229.37 user query end INSERT INTO `table` .... ­­­TRANSACTION 0 480206289, ACTIVE 70 sec, process no 27230, OS thread id 1178425696 mysql tables in use 1, locked 1 1 lock struct(s), heap size 368, 0 row lock(s), undo log entries 1 MySQL thread id 373, query id 123149 10.120.229.37 user query end INSERT INTO `table` .... ....
21. ODTUG – June 2010 Engine Status Example (2) ------------------------ LATEST DETECTED DEADLOCK ------------------------ 090624 14:32:18 *** (1) TRANSACTION: TRANSACTION 0 39639074, ACTIVE 0 sec, process no 27807, OS thread id 1176562016 inserting mysql tables in use 1, locked 1 LOCK WAIT 7 lock struct(s), heap size 1216 MySQL thread id 1225, query id 4695283 10.120.19.204 db update INSERT INTO table VALUES(254381,638,1,57) *** (1) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 0 page no 6371457 n bits 248 index `PRIMARY` of table `db/table` trx id 0 39639074 lock_mode X insert intention waiting Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0 0: len 8; hex 73757072656d756d; asc supremum;; *** (2) TRANSACTION: TRANSACTION 0 39639079, ACTIVE 0 sec, process no 27807, OS thread id 1179224416 inserting, thread declared inside InnoDB 500 mysql tables in use 1, locked 1 7 lock struct(s), heap size 1216 MySQL thread id 1229, query id 4695295 prodgos23.eao.abn-iad.ea.com 10.120.19.204 madden_2010 update INSERT INTO table VALUES(254382,746,1,57) *** (2) HOLDS THE LOCK(S): RECORD LOCKS space id 0 page no 6371457 n bits 248 index `PRIMARY` of table `madden_2010_franchise_xbl2/franchise_draft_board` trx id 0 39639079 lock_mode X Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0 0: len 8; hex 73757072656d756d; asc supremum;; *** (2) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 0 page no 6371457 n bits 248 index `PRIMARY` of table `db/table` trx id 0 39639079 lock_mode X insert intention waiting Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0 0: len 8; hex 73757072656d756d; asc supremum;; *** WE ROLL BACK TRANSACTION (2)
22. ODTUG – June 2010 Status Variables Shows incrementing internal counters Volume of SQL Read/Write ratio
23. ODTUG – June 2010 Status Variables mysql> SHOW GLOBAL STATUS; $ mysqladmin extended­status mysql> SELECT * FROM GLOBAL_STATUS (5.1) http://dev.mysql.com/doc/refman/5.1/en/show-status.html
24. ODTUG – June 2010 Status Variables Example | Com_select | 553971 | | Com_insert | 64068 | | Com_insert_select | 6521 | | Com_update | 190627 | | Com_update_multi | 4809 | | Com_delete | 95197 | | Com_delete_multi | 1408 | | Com_replace | 1549 | | Com_replace_select | 0 |
25. ODTUG – June 2010 Status Variables Example (2) | Bytes_received | 635778091 | | Bytes_sent | 4207810294 | | Threads_connected | 22 | | Threads_running | 3 | Throughput | Bytes_received | 635778091 | | Bytes_sent | 4207810294 | Load | Threads_connected | 22 | | Threads_running | 3 | Server Running | Uptime | 5951 |
26. ODTUG – June 2010 Status Variables Example (3) • $ mysqladmin ­u ­p ­r ­s 1 extended status | grep ­v “| 0” +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­+ | Variable_name | Value | +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­+ | Bytes_received | 8888 | | Bytes_sent | 151482 | | Com_select | 114 | | Com_show_status | 1 | | Created_tmp_tables | 2 | | Handler_read_key | 194 | | Handler_read_next | 273 | | Handler_read_rnd | 165 | | Handler_read_rnd_next | 47416 | | Handler_write | 289 | | Key_read_requests | 1555 | | Questions | 116 | | Select_range | 23 | | Select_scan | 3 | | Sort_rows | 165 | | Sort_scan | 3 | | Table_locks_immediate | 115 | | Threads_connected | ­1 | | Threads_running | ­1 | | Uptime | 1 | | Uptime_since_flush_status | 1 | +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­+
27. ODTUG – June 2010 MySQL Proxy Included histogram.lua Gives read/write breakdown per table Shows top executing queries by frequency Shows max and avg execution time http://dev.mysql.com/doc/refman/5.1/en/mysql-proxy.html https://launchpad.net/mysql-proxy http://ronaldbradford.com/blog/sql-query-analysis-with-mysql-proxy-2009-09-02/
28. ODTUG – June 2010 MySQL Proxy Example mysql> select * from histogram.tables; +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­+ | table | reads | writes | +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­+ | schema1.dotCommLookup | 991 | 0 | | schema2xxxxxx.dotCommClient | 6 | 0 | | schema2xxxxxx.ReleaseNumbers | 3 | 6 | | schema2xxxxxx.PAYCYCLE | 1 | 0 | | schema1.dotCommClient | 1505 | 0 | | schema1.Job | 131 | 0 | | schema2xxxxxx.CondMod | 0 | 28 | | schema2xxxxxx.SPINFO | 3 | 0 | | schema1.Poll | 1184 | 633 | | schema2xxxxxx.LaborSchedules | 0 | 96 | | schema1.JobRequest | 192 | 0 | | schema1.PollTasks | 454 | 1048 | | schema1.Tasks | 1048 | 0 | | schema1.auth | 141 | 59 | | schema2xxxxxx.dotComm | 2 | 0 | | schema2xxxxxx.MenuItem | 0 | 2446 | | schema1.Location | 19 | 118 | | schema2xxxxxx.CONCASH | 2 | 0 | | schema1.dotComm | 156 | 0 | | schema1.Client | 47 | 0 | +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­+ 20 rows in set (0.00 sec)
29. ODTUG – June 2010 MySQL Proxy Example (2) mysql> select * from histogram.queries; *************************** 8. row *************************** query: SELECT `type` , COUNT( * ) AS `count` FROM `schema1` . `table1` `a` WHERE `clientID` = ? AND `bocDate` = ? AND `locationID` IN( ? ) GROUP BY ? ORDER BY ? count: 8 max_query_time: 12932 avg_query_time: 4154.125 *************************** 35. row *************************** query: SELECT `empl_first_nam` , `empl_last_nam` , `empl_mid_initial` FROM `schema2` . `table2` WHERE `clientID` = ? AND `empl_ssn` = ? AND `locationID` = ? LIMIT ? count: 84 max_query_time: 61974 avg_query_time: 2501.3095238095 *************************** 305. row *************************** query: INSERT INTO `schema3` . `table3` SET `eventTime` = NOW( ) , `event` = ? , `userID` = ? , `details` = ? count: 59 max_query_time: 433610 avg_query_time: 38760.983050847 *************************** 302. row *************************** query: SELECT * FROM `table4` WHERE `jobID` = ? AND `taskID` = ? count: 1056 max_query_time: 17564 avg_query_time: 672.67708333333
30. ODTUG – June 2010 TCP/IP Capture Captures network packets http://www.tcpdump.org/tcpdump_man.html
31. ODTUG – June 2010 TCP/IP Example 2010­05­18 19:08:09.291455 IP 999.67.245.14.3338 > 999.174.90.144.3306: tcp 0 0x0000: 4500 0030 fdd0 4000 7106 e466 4b43 f50e E..0..@.q..fKC.. 0x0010: 8cae 5a90 0d0a 0cea e1cd 4d71 0000 0000 ..Z.......Mq.... 0x0020: 7002 ffff 125c 0000 0204 05b4 0101 0402 p....\.......... 2010­05­18 19:08:09.291519 IP 999.174.90.144.3306 > 999.67.245.14.3338: tcp 0 0x0000: 4500 0030 0000 4000 4006 1338 8cae 5a90 E..0..@.@..8..Z. 0x0010: 4b43 f50e 0cea 0d0a 69af 73bf e1cd 4d72 KC......i.s...Mr 0x0020: 7012 16d0 1e0c 0000 0204 05b4 0101 0402 p............... 2010­05­18 19:08:09.316990 IP 999.67.245.14.3338 > 999.174.90.144.3306: tcp 0 0x0000: 4500 0028 fdd1 4000 7106 e46d 4b43 f50e E..(..@.q..mKC.. 0x0010: 8cae 5a90 0d0a 0cea e1cd 4d72 69af 73c0 ..Z.......Mri.s. 0x0020: 5010 ffff 61a0 0000 P...a... 2010­05­18 19:08:09.322483 IP 999.174.90.144.3306 > 999.67.245.14.3338: tcp 67 0x0000: 4508 006b 7eed 4000 4006 9407 8cae 5a90 E..k~.@.@.....Z. 0x0010: 4b43 f50e 0cea 0d0a 69af 73c0 e1cd 4d72 KC......i.s...Mr 0x0020: 5018 16d0 574b 0000 3f00 0000 0a35 2e30 P...WK..?....5.0 0x0030: 2e35 3161 2d63 6f6d 6d75 6e69 7479 0036 .51a­community.6 0x0040: 9800 0057 7462 6f28 732f 2e00 2ca2 0802 ...Wtbo(s/..,... 0x0050: 0000 0000 0000 0000 0000 0000 0000 386f ..............8o 0x0060: 4858 615f 3838 5274 7055 00 HXa_88RtpU. tcpdump -i any -s 65535 -x -nn -q -tttt port 3306
32. ODTUG – June 2010 DTrace/SystemTap Observability technologies Enable the behavior of running systems and applications to be investigated Zero probe effect when not enabled http://www.sun.com/bigadmin/content/dtrace/index.jsp http://sourceware.org/systemtap/
33. ODTUG – June 2010 SystemTap Example # stap query_trace.sty /home/posulliv/repos/mysql/mysql-5.5.2-m2/5.5.2/libexec/mysqld select @@version_comment limit 1 Total: 287us Locks: 0us Engine: 0us Network: 6us Filesort: 0us select USER() Total: 127us Locks: 0us Engine: 0us Network: 6us Filesort: 0us SELECT DATABASE() Total: 562us Locks: 0us Engine: 0us Network: 21us Filesort: 0us show databases Total: 642us Locks: 0us Engine: 5us Network: 6us Filesort: 0us show tables Total: 1148us Locks: 0us Engine: 6us Network: 6us Filesort: 0us show tables Total: 6201us Locks: 0us Engine: 19us Network: 23us Filesort: 0us SELECT DATABASE() Total: 564us Locks: 0us Engine: 0us Network: 21us Filesort: 0us show databases Total: 81us Locks: 0us Engine: 5us Network: 6us Filesort: 0us show tables Total: 293us Locks: 0us Engine: 5us Network: 6us Filesort: 0us select * from t1 Total: 1202us Locks: 32us Engine: 20us Network: 23us Filesort: 0us select * from t1 where a = 1 Total: 1134us Locks: 30us Engine: 56us Network: 21us Filesort: 0us select * from t1 order by a desc Total: 4727us Locks: 26us Engine: 20us Network: 22us Filesort: 3182us insert into t1 values (3, 'tomas') Total: 3406us Locks: 146us Engine: 858us Network: 30us Filesort: 0us select * from t1 order by a desc Total: 1340us Locks: 27us Engine: 20us Network: 21us Filesort: 228us ^C
34. ODTUG – June 2010 Analyzing your SQL
35. ODTUG – June 2010 Bulk Analysis Tools Your eyes Maatkit mk-query-digest
36. ODTUG – June 2010 Slow Query Log mk-query-digest --type slowlog /path/to/slow.log Best practice to roll/analyze daily http://ronaldbradford.com/blog/the-correct-approach-to-rolling-mysql-logs-2010-02-22/
37. ODTUG – June 2010 Slow Query Analysis Example • $ mk­query­digest ­­type slowlog /var/log/mysql/slow.log • # Query 1: 0.00 QPS, 2.74x concurrency, ID 0x036A4959F0EBB3BD at byte ­1 _ # pct total min max avg 95% stddev median # Count 1 395 # Exec time 28 478528s 11s 4733s 1211s 4168s 1431s 511s # Lock time 20 31777s 0 2769s 80s 685s 291s 0 # Rows sent 0 3.86k 10 10 10 10 0 10 # Rows exam 3 193.22M 500.73k 500.96k 500.90k 485.50k 0 485.50k # Users 1 xxx # Hosts 5 app5.xxxxx... (128), app1.xxxx... (85)... 3 more # Databases 1 xxxx # Time range 2009­05­18 10:23:18 to 2009­05­20 10:50:14 # bytes 0 184.67k 476 479 478.73 463.90 0 463.90 # Query_time distribution # 1us # 10us # 100us # 1ms # 10ms # 100ms # 1s # 10s+ ################################################################
38. ODTUG – June 2010 Slow Query Analysis Example # Tables # SHOW TABLE STATUS FROM `xxxx` LIKE 'gg'\G # SHOW CREATE TABLE `xxxx`.`gg`\G # SHOW TABLE STATUS FROM `xxxx ` LIKE 'gr'\G # SHOW CREATE TABLE `xxxx `.`gr`\G # SHOW TABLE STATUS FROM `xxxx ` LIKE 'tt'\G # SHOW CREATE TABLE `xxxx `.`tt`\G # EXPLAIN SELECT tt.*, (SELECT COUNT(*) FROM gg WHERE gg.tt_user_id = tt.id) AS g_c, (SELECT COUNT(*) FROM WHERE gr.tt_user_id = tt.id ) AS r_c FROM tt AS tt WHERE 1 AND tt.user_type = 'CUSTOMER' GROUP BY tt.id HAVING g_c > 1 OR r_c > 1 ORDER BY tt.id desc, g_c DESC , r_c DESC LIMIT 10 OFFSET 0\G
39. ODTUG – June 2010 General Query Log • $ mk­query­digest ­­type genlog ­­report­format profile /opt/mysql_sandboxes/latest/data/msandbox.log # 2.4s user time, 40ms system time, 37.40M rss, 78.70M vsz # Current date: Fri Jun 11 14:17:22 2010 # Files: /opt/mysql_sandboxes/latest/data/msandbox.log # Overall: 17.11k total, 2.64k unique, 0.71 QPS, 0x concurrency __________ # total min max avg 95% stddev median # Exec time 0 0 0 0 0 0 0 # Time range 2010­06­11 07:35:44 to 2010­06­11 14:17:01 # bytes 793.75k 11 26.50k 47.52 54.21 295.84 38.53 # Profile # Rank Query ID Response time Calls R/Call Item # ==== ================== ================ ===== ======== ================ # 1 0xC9EEB2D51C356A33 0.0000 0.0% 3622 0.0000 SET # 2 0x6C099B0B73EA7633 0.0000 0.0% 608 0.0000 USE # 3 0xAC5C18B304F9DE87 0.0000 0.0% 595 0.0000 SELECT # 4 0x30FE5C2032672827 0.0000 0.0% 595 0.0000 SHOW TABLE STATUS # 5 0x1D7CBA0BE5BAA758 0.0000 0.0% 595 0.0000 SHOW TRIGGERS # 6 0xAEA9A980826923AF 0.0000 0.0% 595 0.0000 SET # 7 0x10AB55EA465447D0 0.0000 0.0% 565 0.0000 ADMIN FIELD # 8 0x5D51E5F01B88B79E 0.0000 0.0% 522 0.0000 ADMIN CONNECT # 9 0xAA353644DE4C4CB4 0.0000 0.0% 438 0.0000 ADMIN QUIT # 10 0xE3A3649C5FAC418D 0.0000 0.0% 410 0.0000 SELECT # 11 0x28FC5B5D583E2DA6 0.0000 0.0% 402 0.0000 SHOW STATUS # 12 0x3AEAAD0E15D725B5 0.0000 0.0% 107 0.0000 SET # 13 0x3607184B9D9C3A96 0.0000 0.0% 107 0.0000 SELECT # 14 0x44001A2E53C1AB70 0.0000 0.0% 107 0.0000 SET # 15 0xA2750AF24EA2AEE6 0.0000 0.0% 107 0.0000 SHOW COLLATION # 16 0x38B3D80280BBFA2A 0.0000 0.0% 107 0.0000 SET # 17 0xC69B6ED2C47380A4 0.0000 0.0% 107 0.0000 SHOW VARIABLES # 18 0xE4CF7146873CCC28 0.0000 0.0% 107 0.0000 SET # 19 0x5CBA2034458B5BC9 0.0000 0.0% 95 0.0000 SHOW DATABASES # 20 0x2DE40AAFA6F4B715 0.0000 0.0% 46 0.0000 INSERT SELECT TEMP.task
40. ODTUG – June 2010 General Query Log Analysis $ mk­query­digest ­­type genlog /opt/mysql_sandboxes/latest/data/msandbox.log # Query 20: 0 QPS, 0x concurrency, ID 0x2DE40AAFA6F4B715 at byte 56687 ___ # This item is included in the report because it matches ­­limit. # pct total min max avg 95% stddev median # Count 0 46 # Exec time 0 0 0 0 0 0 0 0 # Databases 1 anonymous # Time range 2010­06­11 09:33:04 to 2010­06­11 09:33:04 # bytes 3 25.72k 404 1.12k 572.57 833.10 157.30 511.45 # Query_time distribution # 1us # 10us # 100us # 1ms # 10ms # 100ms # 1s # 10s+ # Tables # SHOW TABLE STATUS FROM `TEMP` LIKE 'task'\G # SHOW CREATE TABLE `TEMP`.`task`\G insert into TEMP.task( task_type, state, user_table_schema, user_table_table, user _table_depth, artifact_schema, artifact_table, command ) values( 'GenerateFinalBySort', 'waiting', 'drupal', 'node_revisions', '0', 'TEMP', 'node_revisions$final', 'create table `TEMP`.`node_revisions$final`(`nid` int, `vid` int, `uid` int, `title` varchar(255), `body` longtext, `teaser` longtext, `log` longtext, `timestamp` int, `format` int) select `nid`, `vid`, `uid`, `title`, `body`, `teaser`, `log`, `timestamp`, `format` from `drupal`.`node_revisions` order by `vid`')\G
41. ODTUG – June 2010 Binary Log mysql> SHOW GLOBAL VARIABLES LIKE 'log_bin'; mysql> SHOW MASTER STATUS; mysql> SHOW MASTER LOGS;
42. ODTUG – June 2010 Aggregating Binlog Output 33389 update e_acc 17680 insert into r_b 17680 insert into e_rec 14332 insert into rcv_c 13543 update e_rec 10805 update loc 3339 insert into r_att 2781 insert into o_att mysqlbinlog /path/to/mysql­bin.000999 | \ grep ­i ­e "^update" ­e "^insert" ­e "^delete" ­e "^replace" ­e "^alter" | \ cut ­c1­100 | tr '[A­Z]' '[a­z]' | \ sed ­e "s/\t/ /g;s/\`//g;s/(.*$//;s/ set .*$//;s/ as .*$//" | \ sed ­e "s/ where .*$//" | \ sort | uniq ­c | sort ­nr
43. ODTUG – June 2010 Maatkit $ mysqlbinlog /opt/mysql_sandboxes/latest/data/msandbox.000001 \ > | ./mk­query­digest ­­type binlog ­­report­format profile # Profile # Rank Query ID Response time Calls R/Call Item # ==== ================== ================ ===== ======== ================ # 1 0xBE1EAF34D33DE48B 0.0000 0.0% 3 0.0000 CREATE TABLE coitest_?k.customers `bulkload`.`customers$final` # 2 0x0A44B866EBFF94FC 0.0000 0.0% 3 0.0000 DROP # 3 0x7B747B0DEABCA018 0.0000 0.0% 3 0.0000 CREATE TABLE coitest_?k.orders `bulkload`.`orders$final` # 4 0xB4E2D6D6475B00FF 0.0000 0.0% 3 0.0000 DROP # 5 0xF5DAC1762A3DE61F 0.0000 0.0% 3 0.0000 DROP # 6 0x42EF521F930E2DB7 0.0000 0.0% 3 0.0000 CREATE TABLE coitest_?k.orders `bulkload`.`orders$parent` # 7 0xE4D87F83229BB741 0.0000 0.0% 18 0.0000 UPDATE bulkload.task # 8 0x5A7960FD3F39E5F8 0.0000 0.0% 3 0.0000 CREATE TABLE bulkload.progress # 9 0x813031B8BBC3B329 0.0000 0.0% 60141 0.0000 COMMIT # 10 0x854DE5DBCC259DFB 0.0000 0.0% 30000 0.0000 INSERT bulkload.items$parent # 11 0x3FBD919BC7E69704 0.0000 0.0% 87 0.0000 INSERT bulkload.progress # 12 0xE50052BA71B4D17C 0.0000 0.0% 3 0.0000 DROP TABLE if # 13 0xD645DADD65C8DD01 0.0000 0.0% 18 0.0000 INSERT SELECT bulkload.task # 14 0x5B6EB50967F9BAB8 0.0000 0.0% 18 0.0000 UPDATE bulkload.task # 15 0x277902B2380B46B4 0.0000 0.0% 1 0.0000 DROP # 16 0x15174D089E600489 0.0000 0.0% 3 0.0000 CREATE TABLE bulkload.task # 17 0x6F1EE7DAFC74D9AF 0.0000 0.0% 3 0.0000 CREATE TABLE coitest_?k.items `bulkload`.`items$child` # 18 0x85FFF5AA78E5FF6A 0.0000 0.0% 60141 0.0000 BEGIN # 19 0x9EE6FD43C5546BA1 0.0000 0.0% 3 0.0000 CREATE TABLE bulkload.items$parent `bulkload`.`items$parent` # 20 0x51DCCB95FA917A6F 0.0000 0.0% 3 0.0000 DROP TABLE if
44. ODTUG – June 2010 Status variables Analysis Gathering global status per time interval Reporting options statpack http://ronaldbradford.com/blog/using-statpack-with-show-status-2009-06-18/
45. ODTUG – June 2010 statpack Example ==================================================================================================== Uptime: 17 days 17 hours 22 mins Snapshot Period 1: 59 minute interval ==================================================================================================== Variable Delta/Percentage Per Second Total =================================================================================... ==================================================================================================== Statement Activity ==================================================================================================== SELECT: 13,503,876 3,798.56 4,298,170,239 (94.25%) INSERT: 91,101 25.63 25,327,062 (0.56%) UPDATE: 782,004 219.97 220,640,296 (4.84%) DELETE: 9,674 2.72 2,485,643 (0.05%) COMMIT: 46,422 13.06 13,700,478 (0.30%) ROLLBACK: 0 0.00 13 (0.00%) ... ==================================================================================================== Temporary Space ==================================================================================================== tmp_table_size Efficiency: 2.10% Memory Temp Tables: 26,467 7.45 9,335,030 Disk Temp Tables: 25,951 7.30 9,138,705 Temp Files: 2 0.00 601
46. ODTUG – June 2010 TCP/IP Dump Analysis Non-intrusive Close to full sample Near realtime $ tcpdump ­i eth0 port 3306 ­s 65535 ­x \ > ­n ­q ­tttt ­c 1000 > tcpdump.out $ cat tcpdump.out | mk­query­digest ­­type tcpdump
47. ODTUG – June 2010 TCP/IP Dump Summary # 4.1s user time, 85.9ms system time, 17.85M rss, 18.46M vsz # Overall: 1.99k total, 86 unique, 321.13 QPS, 0.21x concurrency _________ # total min max avg 95% stddev median # Exec time 1s 39us 70ms 649us 839us 4ms 152us # Time range 2010­03­30 17:52:42.569092 to 2010­03­30 17:52:48.772254 # bytes 186.80k 13 1.61k 96.03 166.51 196.84 40.45 # Rows affe 59 0 2 0.03 0 0.18 0 # Warning c 5 0 2 0.00 0 0.07 0 # 4% (98) No_index_used # Profile # Rank Query ID Response time Calls R/Call Item # ==== ================== ================ ===== ======== ================ # 3 0xC9ECBBF2C88C2336 0.0875 7.5% 568 0.0002 SELECT r_c # 4 0x448E4AEB7E02AF72 0.0785 6.7% 566 0.0001 SELECT r_t # 5 0xCF3A86CFCC509800 0.0596 5.1% 5 0.0119 SELECT h_c_i # 6 0x8D86ED007917BCE6 0.0480 4.1% 131 0.0004 SELECT loc # 7 0xDB8614598CD1ED36 0.0416 3.6% 1 0.0416 SELECT lml r # 8 0x9BA140CF9CE950C8 0.0316 2.7% 1 0.0316 SELECT bsc # 9 0x633F85619F198C33 0.0219 1.9% 23 0.0010 SELECT hlm mt # 10 0xADCCD37E265C8300 0.0197 1.7% 79 0.0002 SELECT h_l_l
48. ODTUG – June 2010 TCP/IP Dump Query Review # Query 6: 23.02 QPS, 0.01x concurrency, ID 0x8D86ED007917BCE6 at byte ­2 # This item is included in the report because it matches ­­limit. # pct total min max avg 95% stddev median # Count 6 131 # Exec time 3 48ms 160us 5ms 366us 690us 477us 247us # Hosts 5 10.0.0.77 (86), 10.0.0.36 (21), 10.0.0.79 (20)... 2 more # Time range 2010­03­30 17:52:43.034021 to 2010­03­30 17:52:48.724815 # bytes 8 15.93k 123 125 124.54 124.25 1 124.25 # Errors 1 none # Rows affe 0 0 0 0 0 0 0 0 # Warning c 0 0 0 0 0 0 0 0 # Query_time distribution # 1us # 10us # 100us ################################################################ # 1ms ## # 10ms # 100ms # 1s # 10s+ # Tables # SHOW TABLE STATUS LIKE 'loc'\G # SHOW CREATE TABLE `loc`\G # EXPLAIN SELECT l.* FROM loc p, loc l WHERE p.id=2090 AND l.lft BETWEEN p.lft AND p.rgt AND l.depth=p.depth+1 ORDER BY l.lft\G
49. ODTUG – June 2010 mycheckpoint SQL orientated monitoring utility for MySQL Measures various metrics Stores measurements in database Metrics can be accessed through SQL Can generate HTML reports and Google charts easily http://code.openark.org/forge/mycheckpoint/documentation
50. ODTUG – June 2010 SQL Analysis Tools EXPLAIN mk-visual-explain SHOW CREATE TABLE SHOW INDEXES SHOW TABLE STATUS I_S Table/Index size SHOW SESSION STATUS SHOW PROFILE
51. ODTUG – June 2010 Explain Returns information on query plan Query not actually executed (unless query contains sub-query) 1 row in output per table EXPLAIN EXTENDED shows query actually executed http://dev.mysql.com/doc/refman/5.1/en/explain.html
52. ODTUG – June 2010 Explain Examples mysql> explain select 1; +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­+ 1 row in set (0.00 sec) mysql> explain select 1\G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: NULL type: NULL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: NULL Extra: No tables used 1 row in set (0.00 sec) mysql>
53. ODTUG – June 2010 Explain Examples mysql> explain ­> select ­> avg(length(w.variables)) / 1048576 ­> from ­> watchdog w ­> \G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: w type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 69248 Extra: 1 row in set (0.00 sec) mysql>
54. ODTUG – June 2010 mk-visual-explain Reverse engineers explain output from MySQL Formats MySQL explain output as a left- deep tree Can take piped input or can process explain plans from input file http://www.maatkit.org/doc/mk-visual-explain.html
55. ODTUG – June 2010 mk-visual-explain Examples Filesort +­ TEMPORARY table temporary(b,r) +­ JOIN +­ Distinct/Not­Exists | +­ Filter with WHERE | +­ Index lookup | key r­>PRIMARY | possible_keys PRIMARY | key_len 292 | ref drupal.b.module,drupal.b.delta | rows 3 +­ Filter with WHERE +­ Bookmark lookup +­ Table | table b | possible_keys tmd,list +­ Index lookup key b­>tmd possible_keys tmd,list key_len 194 ref con echo "explain SELECT DISTINCT b.* FROM blocks b LEFT JOIN blocks_roles r ON b.module = r.module AND b.delta = r.delta WHERE b.theme = 'garland' AND b.status = 1 AND (r.rid IN (2) OR r.rid IS NULL) ORDER BY b.region, b.weight, b.module" | \ mysql ­u root drupal | \ mk­visual­explain
56. ODTUG – June 2010 Show Create Table Shows full definition Includes all keys Shows storage engine http://dev.mysql.com/doc/refman/5.1/en/show-create-table.html SHOW CREATE TABLE [schema.]tablename
57. ODTUG – June 2010 Show Create Table Example mysql> SHOW CREATE TABLE wp_postmeta\G *************************** 1. row *************************** Table: wp_postmeta Create Table: CREATE TABLE `wp_postmeta` ( `meta_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT, `post_id` bigint(20) unsigned NOT NULL DEFAULT '0', `meta_key` varchar(255) DEFAULT NULL, `meta_value` longtext, PRIMARY KEY (`meta_id`), KEY `post_id` (`post_id`), KEY `meta_key` (`meta_key`) ) ENGINE=MyISAM AUTO_INCREMENT=1745 DEFAULT CHARSET=utf8 1 row in set (0.00 sec)
58. ODTUG – June 2010 Show Indexes Provides cardinality http://dev.mysql.com/doc/refman/5.1/en/show-index.html SHOW INDEX[ES] [FROM|IN] [schema.]tablename
59. ODTUG – June 2010 Show Index Example mysql> SHOW INDEXES FROM wp_postmeta; +­­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­+­­­­­­+­­­­­­­­­­­­+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | +­­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­+­­­­­­+­­­­­­­­­­­­+ | wp_postmeta | 0 | PRIMARY | 1 | meta_id | A | 1351 | NULL | NULL | | BTREE | | wp_postmeta | 1 | post_id | 1 | post_id | A | 450 | NULL | NULL | | BTREE | | wp_postmeta | 1 | meta_key | 1 | meta_key | A | 7 | NULL | NULL | YES | BTREE | +­­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­+­­­­­­+­­­­­­­­­­­­+
60. ODTUG – June 2010 Table Status SHOW TABLE STATUS [IN schema] LIKE 'tablename' http://dev.mysql.com/doc/refman/5.1/en/show-table-status.html
61. ODTUG – June 2010 Table Status Example mysql> SHOW TABLE STATUS LIKE 'wp_postmeta'\G *************************** 1. row *************************** Name: wp_postmeta Engine: MyISAM Version: 10 Row_format: Dynamic Rows: 1351 Avg_row_length: 46 Data_length: 62960 Max_data_length: 281474976710655 Index_length: 58368 Data_free: 76 Auto_increment: 1745 Create_time: 2009­09­08 09:57:51 Update_time: 2010­06­04 15:06:47 Check_time: 2010­06­01 11:12:54 Collation: utf8_general_ci Checksum: NULL Create_options: Comment: 1 row in set (0.00 sec)
62. ODTUG – June 2010 Information Schema INFORMATION_SCHEMA TABLES COLUMNS Meta data Simple view of DBA_TABLES/COLUMNS http://dev.mysql.com/doc/refman/5.1/en/information-schema.html
63. ODTUG – June 2010 Information Schema Example SELECT table_schema, table_name, engine, row_format, table_rows, avg_row_length, (data_length+index_length)/1024/1024 as total_mb, (data_length)/1024/1024 as data_mb, (index_length)/1024/1024 as index_mb, CURDATE() AS today FROM information_schema.tables WHERE table_schema=DATABASE() ORDER BY 7 DESC; http://ronaldbradford.com/mysql-dba/#perschema
64. ODTUG – June 2010 Information Schema Example +­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+ | table_name | engine | row_format | table_rows | avg_row_length | total_mb | data_mb | index_mb | +­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+ | xxxxxxx | InnoDB | Compact | 1778523 | 314 | 658.39062500 | 533.84375000 | 124.54687500 | | xxxxxxxxx | InnoDB | Compact | 553266 | 846 | 472.25000000 | 446.75000000 | 25.50000000 | | xxxxxxx | InnoDB | Compact | 435892 | 884 | 392.25000000 | 367.81250000 | 24.43750000 | | xxxxxxxxxxxxxx | InnoDB | Compact | 1106547 | 65 | 133.26562500 | 68.59375000 | 64.67187500 | | xxxxxxxxxxxxxxxx | InnoDB | Compact | 58281 | 531 | 30.34375000 | 29.51562500 | 0.82812500 | | xxxxxxxxxx | InnoDB | Compact | 68721 | 298 | 28.12500000 | 19.54687500 | 8.57812500 | ...
65. ODTUG – June 2010 Show Session Status MySQL Internal counters http://dev.mysql.com/doc/refman/5.1/en/show-status.html
66. ODTUG – June 2010 Show Session Status Example SHOW SESSION STATUS LIKE 'Created%'; +­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+ | Variable_name | Value | +­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+ | Created_tmp_disk_tables | 1 | | Created_tmp_files | 5 | | Created_tmp_tables | 3 | +­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+ SHOW SESSION STATUS LIKE 'Created%'; +­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+ | Variable_name | Value | +­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+ | Created_tmp_disk_tables | 2 | | Created_tmp_files | 5 | | Created_tmp_tables | 3 | +­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­+ SELECT ...;
67. ODTUG – June 2010 Show Profile Provides internal message calls Descriptions not always accurate http://dev.mysql.com/doc/refman/5.1/en/show-profiles.html SET PROFILING = 1; SHOW PROFILES; SHOW PROFILE [FOR QUERY n];
68. ODTUG – June 2010 Show Profile Example mysql> SHOW PROFILES\G *************************** 1. row *************************** Query_ID: 1 Duration: 0.00081600 Query: SELECT t.*, tt.*, tr.object_id FROM wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON tt.term_id = t.term_id INNER JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ('category', 'post_tag') AND tr.object_id IN (2487) ORDER BY t.name ASC
69. ODTUG – June 2010 Show Profile Example (2) mysql> SHOW PROFILE SOURCE FOR QUERY 1; +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­­­+ | Status | Duration | Source_function | Source_file | Source_line | +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­­­+ | starting | 0.000049 | NULL | NULL | NULL | | checking query cache for query | 0.000074 | unknown function | sql_cache.cc | 1446 | | Opening tables | 0.000013 | unknown function | sql_base.cc | 4495 | | System lock | 0.000005 | unknown function | lock.cc | 258 | | Table lock | 0.000032 | unknown function | lock.cc | 269 | | init | 0.000038 | unknown function | sql_select.cc | 2484 | | optimizing | 0.000014 | unknown function | sql_select.cc | 820 | | statistics | 0.000135 | unknown function | sql_select.cc | 1011 | | preparing | 0.000017 | unknown function | sql_select.cc | 1033 | | Creating tmp table | 0.000155 | unknown function | sql_select.cc | 1524 | | executing | 0.000002 | unknown function | sql_select.cc | 1755 | | Copying to tmp table | 0.000142 | unknown function | sql_select.cc | 1902 | | Sorting result | 0.000026 | unknown function | sql_select.cc | 2176 | | Sending data | 0.000051 | unknown function | sql_select.cc | 2309 | | end | 0.000002 | unknown function | sql_select.cc | 2530 | | removing tmp table | 0.000063 | unknown function | sql_select.cc | 10776 | | end | 0.000003 | unknown function | sql_select.cc | 10801 | | query end | 0.000002 | unknown function | sql_parse.cc | 4978 | | freeing items | 0.000017 | unknown function | sql_parse.cc | 6004 | | storing result in query cache | 0.000005 | unknown function | sql_cache.cc | 983 | | logging slow query | 0.000001 | unknown function | sql_parse.cc | 1679 | | cleaning up | 0.000002 | unknown function | sql_parse.cc | 1647 | +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­­­+ 22 rows in set (0.00 sec)
70. ODTUG – June 2010 Show Profile Example (3) mysql> SHOW PROFILES; +­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ | 1 | 0.00084800 | SELECT t.*, tt.*, tr.object_id FROM wp_terms AS t ... | 2 | 0.00006000 | SELECT t.*, tt.*, tr.object_id FROM wp_terms AS t .... +­­­­­­­­­­+­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 2 rows in set (0.00 sec) mysql> SHOW PROFILE SOURCE FOR QUERY 2; +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­+ | starting | 0.000034 | NULL | NULL | NULL | | checking query cache for query | 0.000008 | unknown function | sql_cache.cc | 1446 | | checking privileges on cached | 0.000004 | unknown function | sql_cache.cc | 1534 | | sending cached result to clien | 0.000010 | unknown function | sql_cache.cc | 1629 | | logging slow query | 0.000002 | unknown function | sql_parse.cc | 1679 | | cleaning up | 0.000002 | unknown function | sql_parse.cc | 1647 | +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­+­­­­­­­­­­­­­+
71. ODTUG – June 2010 Optimizing your SQL
72. ODTUG – June 2010 About the MySQL Optimizer Cost based optimizer No way to pin QEP One index per table rule (with exceptions) The lack of good hints No statistics granularity No parallelism http://forge.mysql.com/wiki/How_does_the_MySQL_Optimizer_work http://forge.mysql.com/wiki/How_does_the_MySQL_Optimizer_work
73. ODTUG – June 2010 SQL Optimization Goals Identify the best indexes Reduce unnecessary data access Minimize kernel internals
74. ODTUG – June 2010 Explain Signs No index used Large rows Excessive possible indexes SQL for composite/covering indexes Using Temporary Using filesort Derived tables
75. ODTUG – June 2010 MySQL Index Types Column indexes Composite indexes Covering indexes Partial indexes Spatial indexes Fulltext indexes Clustered indexes Hash indexes http://ronaldbradford.com/blog/understanding-different-mysql-index-implementations-2009-07-22/ http://ronaldbradford.com/blog/understanding-different-mysql-index-implementations-2009-07-22/
76. ODTUG – June 2010 Column Index – Sub-optimal Design CREATE TABLE `content` ( `ContentID` int(11) NOT NULL auto_increment, .... `Promo` tinyint(1) NOT NULL, `Theme` float NOT NULL, `ForDelete` tinyint(1) NOT NULL, PRIMARY KEY (`ContentID`), KEY `CategoryID` (`CategoryID`), KEY `Verified` (`Verified`), KEY `FileName` (`FileName`(10)), KEY `FileDuration` (`FileDuration`), KEY `Votes` (`Votes`), KEY `FileDir` (`FileDir`), KEY `ForDelete` (`ForDelete`), KEY `UserID` (`UserID`), KEY `Type` (`Type`), KEY `CategoryType` (`CategoryType`), KEY `DateAdded` (`DateAdded`) )
77. ODTUG – June 2010 Composite Indexes Example CREATE TABLE relationship ( relation_id bigint NOT NULL auto_increment, type_id bigint default NULL, user_1 bigint NOT NULL, user_2 bigint NOT NULL, ... PRIMARY KEY (relation_id), KEY user_1 (user_1), KEY user_2 (user_2), );
78. ODTUG – June 2010 Composite Indexes explain SELECT user_2 FROM relationship WHERE user_1 = '1580980221' AND user_2 IN (508534334,521894993); +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­+ | 1 | SIMPLE | relationship | range | user_1,user_2 | user_2 | 8 | NULL | 2 | Using where | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­+ ALTER TABLE relationship DROP INDEX user_2, ADD INDEX user_2 (user_2, user_1); +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | relationship | range | user_1,user_2 | user_2 | 16 | NULL | 2 | Using where;Using Index | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+
79. ODTUG – June 2010 Covering Indexes Example CREATE TABLE logging ( source_addr int(10) unsigned NOT NULL, source_port int(9) unsigned NOT NULL, destn_addr int(10) unsigned NOT NULL, destn_port int(9) unsigned NOT NULL, protocol int(9) unsigned NOT NULL, log_time int(11) unsigned NOT NULL, size int(11) unsigned NOT NULL, KEY log_time (log_time), KEY size (size), KEY source_port (src_port), KEY destn_port (destn_port), KEY source_addr (source_addr), KEY destn_addr (dstn_addr) ) ENGINE=MyISAM;
80. ODTUG – June 2010 Covering Indexes SELECT source_port, SUM(size) FROM logging WHERE log_time BETWEEN 1 AND 2 GROUP BY source_port ORDER BY SUM(size) DESC LIMIT 0,20 +­­­­+­­­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | logging | range | log_time | log_t| 4 | NULL | 69997 | Using where; Using temporary; Using filesort | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ By changing the index we achieve an index only scan. ALTER TABLE logging DROP INDEX log_time, DROP INDEX source_port, ADD INDEX (log_time, source_port, size ); +­­­­+­­­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | logging | range | log_time | log_t| 4 | NULL | 69977 | Using where; Using index; Using temporary; Using filesort | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+
81. ODTUG – June 2010 Partial Indexes CREATE TABLE parts( ... brand_id INT UNSIGNED NOT NULL, part_number VARCHAR(30) NOT NULL, manufacturer_name VARCHAR(100) NOT NULL, ... INDEX (brand_id, part_number,manufacturer_name) ) ALTER TABLE parts DROP INDEX brand_id, ADD KEY (brand_id, interchange_part_number, manufacturer_name(8)); Reduced Index size by 30%.
82. ODTUG – June 2010 QEP – Using Filesort EXPLAIN SELECT itemid FROM items WHERE productid=999 GROUP BY itemid; +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | items | ref | productid | productid | 4 | const | 1 | Using where; Using filesort Using filesort | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ 1 row in set (0.00 sec) EXPLAIN SELECT DISTINCT DISTINCT itemid FROM items WHERE productid=999 +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­+ | 1 | SIMPLE | items | ref | productid | productid | 4 | const | 1 | | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­+
83. ODTUG – June 2010 QEP – Using Filesort mysql> show profile source for query 1; +­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­­­+ | Status | Duration | Source_function | Source_file | Source_line | +­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­­­+ | (initialization) | 0.000003 | open_tables | sql_base.cc | ... | preparing | 0.000021 | exec | sql_select.cc | 1594 | | executing | 0.000005 | exec | sql_select.cc | 1990 | | Sorting result | 0.000121 | exec | sql_select.cc | 2114 | | Sending data | 0.000033 | mysql_select | sql_select.cc | 2318 | | end | 0.000007 | mysql_execute_command | sql_parse.cc | 5141 | | query end | 0.000005 | mysql_parse | sql_parse.cc | 6142 | ...
84. ODTUG – June 2010 MySQL Index Sizes NULL columns Bigint vs int InnoDB secondary index PK value
85. ODTUG – June 2010 NULL Index Columns CREATE TABLE child( child_id INT UNSIGNED NOT NULL, parent_id INT UNSIGNED, PRIMARY KEY(child_id), INDEX(parent_id)); mysql> explain select * from child where parent_id=42; +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­+ | 1 | SIMPLE | child | ref | parent_id | parent_id | 5 | const | 1 | Using where | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­+
86. ODTUG – June 2010 NULL Index Columns (2) mysql> SELECT parent_id FROM CHILD PROCEDURE ANALYSE(5,2000)\G *************************** 1. row *************************** Field_name: odtug.CHILD.parent_id Min_value: 1 Max_value: 13 Min_length: 1 Max_length: 2 Empties_or_zeros: 0 Nulls: 0 Avg_value_or_avg_length: 7.0000 Std: 3.7417 Optimal_fieldtype: TINYINT(2) UNSIGNED NOT NULL 1 row in set (0.00 sec)
87. ODTUG – June 2010 NULL Index Columns (3) ALTER TABLE child MODIFY parent_id INT UNSIGNED NOT NULL; +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­+ | 1 | SIMPLE | child | ref | parent_id | parent_id | 4 | const | 1 | | +­­­­+­­­­­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­+­­­­­­+­­­­­­­+
88. ODTUG – June 2010 BIGINT vs INT explain SELECT user_2 FROM relationship WHERE user_1 = '1580980221' AND user_2 IN (508534334,521894993); +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | relationship | range | user_1,user_2 | user_2 | 16 | NULL | 2 | Using where;Using Index | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+ ALTER TABLE relationship MODIFY user_1 INT NOT NULL, MODIFY user_2 INT NOT NULL); explain SELECT user_2 FROM relationship WHERE user_1 = '1580980221' AND user_2 IN (508534334,521894993); +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | relationship | range | user_1,user_2 | user_2 | 8 | NULL | 2 | Using where;Using Index | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­+
89. ODTUG – June 2010 MySQL Index Sizes NULL columns Bigint vs int InnoDB secondary index PK value
90. ODTUG – June 2010 When Indexes Don't Help CREATE TABLE `items` ( `itemid` int(11) NOT NULL auto_increment, `productid` int(11) NOT NULL default '0', ... `itemlive` enum('true','false') NOT NULL default 'true', ... PRIMARY KEY (`itemid`), KEY `productid` (`productid`) KEY `productid` (`productid`), KEY `packaging_cost` (`packaging_cost`) )
91. ODTUG – June 2010 When Indexes Don't Help EXPLAIN SELECT DISTINCT(categories.categoryid) FROM categories, category_product, items WHERE categories.categoryname!='' AND categories.categoryid=category_product.categoryid AND category_product.productid=items.productid AND category_product.productid=items.productid AND items.itemlive='true'; +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | items | ALL | productid | NULL NULL | NULL | NULL | 2906 | Using where; Using temporary | | 1 | SIMPLE | category_product | ref | categoryid,productid | productid | 4 | baris5.items.productid | 1 | | | 1 | SIMPLE | categories | eq_ref | PRIMARY | PRIMARY | 4 | baris5.category_product.categoryid | 1 | Using where | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ 3 rows in set (0.00 sec)
92. ODTUG – June 2010 When Indexes Don't Help Adding an index can reduce this full table scan mysql> alter table items drop index productid, add index (productid,itemlive); +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­ +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­ +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+ | 1 | SIMPLE | items | index | productid | productid | 5 | NULL | 2180 | Using where; Using index; Using temporary | | 1 | SIMPLE | category_product | ref | categoryid,productid | productid | 4 | ronald.items.productid | 1 | | | 1 | SIMPLE | categories | eq_ref | PRIMARY | PRIMARY | 4 | baris5.category_product.categoryid | 1 | Using where | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­­­­+­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­+­­­­­­­­­­­+­­­­­­­­­+­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+­­­­­­ +­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­+
93. ODTUG – June 2010 Optimizing SQL for Locking DML is a blocking statement for MyISAM Long running cleanup scripts 3+ minutes to run SELECT DELETE FROM fts_datacache WHERE productid NOT IN ( SELECT productid FROM xcart_products_categories WHERE categoryid IN (297,1356,1366,1361,1202,...) GROUP BY productid
94. ODTUG – June 2010 Optimizing SQL for Locking Rewriting statement into 2 statements can reduce locking time to ~10 ms CREATE TEMPORARY TABLE delete_cache ( productid INT NOT NULL, primary key (productid)) ENGINE=MEMORY SELECT DISTINCT productid FROM retailbl_xcart.xcart_products_categories WHERE categoryid IN (297,1356,1366,1361,1202,...); DELETE FROM fts_datacache WHERE productid NOT IN (SELECT productid FROM delete_cache);
95. ODTUG – June 2010 Don't Forget Update UPDATE T SET STATE = 'MISFIRED' WHERE (STATE = 'WAITING' OR STATE = 'WAITING') AND NEXT_FIRE_TIME < 263352299544 EXPLAIN SELECT NAME,STATE FROM T WHERE (STATE = 'WAITING' OR STATE = 'WAITING') AND NEXT_FIRE_TIME < 263350625813; +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­+ | 1 | SIMPLE | QRTZ_TRIGGERS | ALL | NULL | NULL | NULL | NULL | 1185 | Using where | +­­­­+­­­­­­­­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­­­­­­­+­­­­­­+­­­­­­­­­+­­­­­­+­­­­­­+­­­­­­­­­­­­­+
96. ODTUG – June 2010 Remove Duplicate Indexes CREATE TABLE `accounts` ( `accountid` int(11) NOT NULL auto_increment, ... `retail_date` date NOT NULL, `customer_survey` tinyint(1) NOT NULL default '1', PRIMARY KEY (`accountid`), KEY `accountid` (`accountid`) KEY `accountid` (`accountid`) ); CREATE TABLE `vehicle_applications` ( PRIMARY KEY (`id`), KEY `mcp_index` (`product_id`,`make`,`model`,`year`), KEY `status_idx` (`status`), KEY `sid_idx` (`status_identifier`), KEY `product_id_idx` (`product_id`), KEY `product_id_idx` (`product_id`), )
97. ODTUG – June 2010 The Most Optimal SQL is the SQL You Can Eliminate
98. ODTUG – June 2010 Eliminating SQL – Example 1 SELECT pages_id, pages_livestats_code, pages_title, pages_parent, pages_exhibid, pages_theme, pages_accession_num FROM pages WHERE pages_id = 0 Following executed 6,000 times in 5 min period 0 is an invalid pages_id
99. ODTUG – June 2010 Eliminating SQL – Example 2 5 Query SELECT * FROM `artist` 5 Query SELECT * FROM `artist` 5 Query SELECT * FROM `artist` 5 Query SELECT * FROM `artist` 5 Query SELECT * FROM `artist` 5 Query SELECT * FROM `artist` WHERE (ArtistID = 196 ) 5 Query SELECT * FROM `artist` WHERE (ArtistID = 2188) 5 Query SELECT * FROM `artist` 5 Query SELECT * FROM `artist` 5 Query SELECT * FROM `artist` Following executed on single page load
100. ODTUG – June 2010 Eliminating SQL – Example 3 Row at a time (RAT) processing SELECT * FROM activities_theme WHERE theme_parent_id=0 SELECT * FROM activities_theme WHERE theme_parent_id=1 SELECT * FROM activities_theme WHERE theme_parent_id=2 SELECT * FROM activities_theme WHERE theme_parent_id=11 SELECT * FROM activities_theme WHERE theme_parent_id=16 Chunk at a time (CAT) processing SELECT * FROM activities_theme WHERE theme_parent_id in (0,1,2,11,16)
101. ODTUG – June 2010 Conclusion
102. ODTUG – June 2010 Capture/Analysis/Optimization Improvement is a reoccurring process Ideally you should analyze all SQL Changes in data size and result set size over time can affect SQL performance