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分类: Mysql/postgreSQL

2010-02-23 14:08:51

2009年09月17日 作者: 大头刚 

mk-query-digest 一个功能很强大的工具,能分析慢查询日志,也可以对当前的语句进行分析等。安装方法查看。

一、分析慢查询日志,生成报表
mysql通过log-slow-queries和long_query_time参数来记录慢查询,默认的格式如下:

# Time: 090909  4:34:28
# User@Host: sparty[sparty] @  [localhost]
# Query_time: 18  Lock_time: 0  Rows_sent: 5  Rows_examined: 52830
select * from test;
# Time: 090909 14:04:24
# User@Host: sparty[sparty] @  [localhost]
# Query_time: 20  Lock_time: 0  Rows_sent: 10  Rows_examined: 2500284
select * from test2;

每产生一条慢查询记录一行,分析起来不直观,也无法进行统计。mk-query-digest能对slow log进行了统计和分析产生报告,可以更具自己的需要,分析出想要的结果。例如

mk-query-digest --limit 2 --select Query_time,Lock_time,Rows_sent,Rows_examined,ts slow.log \
|grep -v '1us' |grep -v '10us'|grep -v '1ms'|grep -v '10ms'|grep -v '100ms'                 \
|grep -v '1s'|grep -v '10s'|grep -v 'SHOW'|grep -v '100us'|grep -v 'EXPLAIN'
 
# Overall: 3 total, 2 unique, 0.00 QPS, 0.00x concurrency ________________
#                    total     min     max     avg     95%  stddev  median
# Exec time            78s      8s     44s     26s     42s     14s     25s
# Lock time            2ms       0     2ms   588us     2ms   822us       0
# Rows sent         23.87M       1  11.93M   7.96M  11.87M   5.59M  11.87M
# Rows exam         35.80M  11.93M  11.93M  11.93M  11.87M       0  11.87M
# Time range        2009-05-20 20:33:59 to 2009-05-27 14:50:13
 
# Query 1: 0.08 QPS, 2.68x concurrency, ID 0x67A347A2812914DF at byte 1240
# This item is included in the report because it matches --limit.
#              pct   total     min     max     avg     95%  stddev  median
# Count         66       2
# Exec time     89     70s     26s     44s     35s     44s     13s     35s
# Lock time      0       0       0       0       0       0       0       0
# Rows sent     99  23.87M  11.93M  11.93M  11.93M  11.93M    0.71  11.93M
# Rows exam     66  23.87M  11.93M  11.93M  11.93M  11.93M    0.71  11.93M
# Time range 2009-05-27 14:49:47 to 2009-05-27 14:50:13
# Query_time distribution
# Tables
SELECT /*!40001 SQL_NO_CACHE */ * FROM `test`\G
 
# Query 2: 0 QPS, 0x concurrency, ID 0x92203A59492D2ECF at byte 0 ________
# This item is included in the report because it matches --limit.
#              pct   total     min     max     avg     95%  stddev  median
# Count         33       1
# Exec time     10      8s      8s      8s      8s      8s       0      8s
# Lock time    100     2ms     2ms     2ms     2ms     2ms       0     2ms
# Rows sent      0       1       1       1       1       1       0       1
# Rows exam     33  11.93M  11.93M  11.93M  11.93M  11.93M       0  11.93M
# Time range 2009-05-20 20:33:59 to 2009-05-20 20:33:59
# Query_time distribution
# Tables
select count(*) from test where t1=20 and t2=100\G
 
# Rank Query ID           Response time    Calls   R/Call     Item
# ==== ================== ================ ======= ========== ====
#    1 0x67A347A2812914DF    69.7409 89.4%       2  34.870474 SELECT test
#    2 0x92203A59492D2ECF     8.2742 10.6%       1   8.274248 SELECT test

报表的输出分三部分,开头部分是整个报表的综合统计。中间部分把单独的Query进行统计,按照total Exec time从高到低排序。结尾部分是输出的每条Query的一些统计。

解释一下主要参数:
–limit 指输出耗时最多的Query的条数限制。
–select 选择需要统计的指标。

二、对当前的查询进行统计分析

mk-query-digest也能使用–processlist参数,对指定mysql的当前Query进行统计分析,例如
mk-query-digest –processlist h=localhost -u sg -p
然后在CTRL+C结束,将对这段时间h=localhost里所进行的所有Query进行统计分析并生成报表,报表的输出和上面介绍的一样。

三、分析慢查询日志,将结果导入到指定表。

mk-query-digest也能使用–review参数,将慢查询日志的分析结果插入到指定表中。
首先需要创建表,存放分析结果:

 CREATE TABLE query_review (
     checksum     BIGINT UNSIGNED NOT NULL PRIMARY KEY,
     fingerprint  TEXT NOT NULL,
     sample       TEXT NOT NULL,
     first_seen   DATETIME,
     last_seen    DATETIME,
     reviewed_by  VARCHAR(20),
     reviewed_on  DATETIME,
     comments     TEXT
  )
  COLUMN       MEANING
  ===========  ===============
  checksum     A 64-bit checksum of the query fingerprint
  fingerprint  The abstracted version of the query; its primary key
  sample       The query text of a sample of the class of queries
  first_seen   The smallest timestamp of this class of queries
  last_seen    The largest timestamp of this class of queries
  reviewed_by  Initially NULL; if set, query is skipped thereafter
  reviewed_on  Initially NULL; not assigned any special meaning
  comments     Initially NULL; not assigned any special meaning

例如:

mk-query-digest --review h=host1,D=test,t=query_review /path/to/slow.log
 
mysql> use test;
Database changed
mysql> select * from query_review\G;
*************************** 1. row ***************************
   checksum: 7467891370387641567
fingerprint: mysqldump
     sample: SELECT /*!40001 SQL_NO_CACHE */ * FROM `test`
 first_seen: 2009-05-27 14:49:47
  last_seen: 2009-05-27 14:50:13
reviewed_by: NULL
reviewed_on: NULL
   comments: NULL
*************************** 2. row ***************************
   checksum: 10529480083946417871
fingerprint: select count(*) from test where test1=? and test2=?
     sample: select count(*) from test where test1=20 and test2=100
 first_seen: 2009-05-20 20:33:59
  last_seen: 2009-05-20 20:33:59
reviewed_by: NULL
reviewed_on: NULL
   comments: NULL
2 rows in set (0.00 sec)

四、查找未走索引的语句

mk-query-digest还可以用来找出当前数据库未走索引的语句,例如我使用下面命令:

tcpdump -i bond0 port 3306 -s 65535 -x -n -q -tttt | mk-query-digest –type tcpdump –filter ‘($event->{No_index_used} || $event->{No_good_index_used})’

然后在CTRL+C结束,将生成下面的报告。

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on bond0, link-type EN10MB (Ethernet), capture size 65535 bytes
3 packets captured
3 packets received by filter
0 packets dropped by kernel
# Caught SIGINT.
# 170ms user time, 20ms system time, 12.00M rss, 73.26M vsz
# Overall: 1 total, 1 unique, 0 QPS, 0x concurrency ______________________
#                    total     min     max     avg     95%  stddev  median
# Exec time          223us   223us   223us   223us   223us       0   223us
# Time range        2009-09-16 09:22:50.637146 to 2009-09-16 09:22:50.637146
# bytes                 26      26      26      26      26       0      26
# Rows affe              0       0       0       0       0       0       0
# Warning c              0       0       0       0       0       0       0
# 100% (1)    No_index_used
 
# Query 1: 0 QPS, 0x concurrency, ID 0x3D8C074C26D05CD7 at byte 0 ________
# This item is included in the report because it matches --limit.
#              pct   total     min     max     avg     95%  stddev  median
# Count        100       1
# Exec time    100   223us   223us   223us   223us   223us       0   223us
# Hosts                  1 10.0.0.203
# Time range 2009-09-16 09:22:50.637146 to 2009-09-16 09:22:50.637146
# bytes        100      26      26      26      26      26       0      26
# Errors                 1    none
# Rows affe      0       0       0       0       0       0       0       0
# Warning c      0       0       0       0       0       0       0       0
# 100% (1)    No_index_used
 
select * from test\G
 
# Rank Query ID           Response time    Calls   R/Call     Item
# ==== ================== ================ ======= ========== ====
#    1 0x3D8C074C26D05CD7     0.0002 100.0%       1   0.000223 SELECT test

很明显,使用tcpdump只能对本地的mysql进行监听,一目了然的找到了哪条sql是没走索引的。

最后,我们在看下这个工具的帮助选项:

mk-query-digest --help
mk-query-digest parses and analyzes MySQL log files.  With no FILE, or when FILE
is -, read standard input.  For more details, please use the --help option, or
try 'perldoc /usr/bin/mk-query-digest' for complete documentation.
 
Usage: /usr/bin/mk-query-digest [OPTION...] [FILE]
 
Options:
 
  --ask-pass                     Prompt for a password when connecting to MySQL
  --attribute-aliases            List of attribute|alias,etc (default db|Schema)
  --attribute-value-limit        A sanity limit for attribute values (default
                                 4294967296)
  --aux-dsn                      Auxiliary DSN used for special options
  --charset                  -A  Default character set
  --check-attributes-limit       Stop checking for new attributes after this
                                 many events (default 1000)
  --config                       Read this comma-separated list of config files;
                                 if specified, this must be the first option on
                                 the command line
  --[no]continue-on-error        Continue parsing even if there is an error
                                 (default yes)
  --create-review-history-table  Create the --review-history table if it does
                                 not exist
  --create-review-table          Create the --review table if it does not exist
  --daemonize                    Fork to the background and detach from the
                                 shell
  --defaults-file            -F  Only read mysql options from the given file
  --embedded-attributes          Two Perl regex patterns to capture
                                 pseudo-attributes embedded in queries
  --execute                      Execute queries on this DSN
  --expected-range               Explain items when there are more or fewer than
                                 expected (default 5,10)
  --explain                      Run EXPLAIN for the sample query with this DSN
                                 and print results
  --filter                       Discard events for which this Perl code doesn't
                                 return true
  --fingerprints                 Add query fingerprints to the standard query
                                 analysis report
  --[no]for-explain              Print extra information to make analysis easy
                                 (default yes)
  --group-by                     Which attribute of the events to group by
                                 (default fingerprint)
  --help                         Show help and exit
  --host                     -h  Connect to host
  --ignore-attributes            Do not aggregate these attributes when
                                 auto-detecting --select (default
                                 s,key,res,val,server_id,offset,end_log_pos,Xid)
  --inherit-attributes           If missing, inherit these attributes from the
                                 last event that had them (default db,ts)
  --interval                     How frequently to poll the processlist, in
                                 seconds (default .1)
  --iterations                   How many times to iterate through the
                                 collect-and-report cycle (default 1)
  --limit                        Limit output to the given percentage or count
                                 (default 95%:20)
  --log                          Print all output to this file when daemonized
  --mirror                       How often to check whether connections should
                                 be moved, depending on read_only
  --order-by                     Sort events by this attribute and aggregate
                                 function (default Query_time:sum)
  --outliers                     Report outliers by attribute:percentile:count
                                 (default Query_time:1:10)
  --password                 -p  Password to use when connecting
  --pid                          Create the given PID file when daemonized
  --port                     -P  Port number to use for connection
  --print                        Print log events to STDOUT in standard
                                 slow-query-log format
  --processlist                  Poll this DSN's processlist for queries, with
                                 --interval sleep between
  --[no]report                   Print out reports on the aggregate results from
                                 --group-by (default yes)
  --report-all                   Include all queries, even if they have already
                                 been reviewed
  --report-format                Print these elements in the query analysis
                                 report (default
                                 rusage,header,query_report,profile)
  --review                       Store a sample of each class of query in this
                                 DSN
  --review-history               The table in which to store historical values
                                 for review trend analysis
  --run-time                     How long to run before exiting.  Optional
                                 suffix s=seconds, m=minutes, h=hours, d=days;
                                 if no suffix, s is used.
  --sample                       Filter out all but the first N occurrences of
                                 each query
  --select                       Compute aggregate statistics for these
                                 attributes
  --set-vars                     Set these MySQL variables (default
                                 wait_timeout=10000)
  --shorten                      Shorten long statements in reports (default
                                 1024)
  --since                        Parse only queries newer than this value (parse
                                 queries since this date)
  --socket                   -S  Socket file to use for connection
  --tcpdump-errors               Write the tcpdump data to this file on error
  --timeline                     Show a timeline of events
  --type                         The type of input to parse (default slowlog)
  --until                        Parse only queries older than this value (parse
                                 queries until this date)
  --user                     -u  User for login if not current user
  --version                      Show version and exit
  --watch-server                 This option tells mk-query-digest which server
                                 IP address and port (like "10.0.0.1:3306") to
                                 watch when parsing tcpdump (for --type tcpdump
                                 and memcached); all other servers are ignored
  --[no]zero-admin               Zero out the Rows_XXX properties for
                                 administrator command events (default yes)
  --zero-bool                    Print 0% boolean values in report
 
Rules:
 
  DSN values in --review-history default to values in --review if COPY is yes.
 
DSN syntax is key=value[,key=value...]  Allowable DSN keys:
 
  KEY  COPY  MEANING
  ===  ====  =============================================
  A    yes   Default character set
  D    yes   Database that contains the query review table
  F    yes   Only read default options from the given file
  P    yes   Port number to use for connection
  S    yes   Socket file to use for connection
  h    yes   Connect to host
  p    yes   Password to use when connecting
  t    no    Table to use as the query review table
  u    yes   User for login if not current user
 
  If the DSN is a bareword, the word is treated as the 'h' key.
 
Options and values after processing arguments:
 
  --ask-pass                     FALSE
  --attribute-aliases            db|Schema
  --attribute-value-limit        4294967296
  --aux-dsn                      (No value)
  --charset                      (No value)
  --check-attributes-limit       1000
  --config                       /etc/maatkit/maatkit.conf,/etc/maatkit/mk-query-digest.conf,/root/.maatkit.conf,/root/.mk-
 
query-digest.conf
  --continue-on-error            TRUE
  --create-review-history-table  FALSE
  --create-review-table          FALSE
  --daemonize                    FALSE
  --defaults-file                (No value)
  --embedded-attributes          (No value)
  --execute                      (No value)
  --expected-range               5,10
  --explain                      (No value)
  --filter                       (No value)
  --fingerprints                 FALSE
  --for-explain                  TRUE
  --group-by                     fingerprint
  --help                         TRUE
  --host                         (No value)
  --ignore-attributes            
 
arg,cmd,insert_id,ip,port,Thread_id,timestamp,exptime,flags,key,res,val,server_id,offset,end_log_pos,Xid
  --inherit-attributes           db,ts
  --interval                     .1
  --iterations                   1
  --limit                        95%:20
  --log                          (No value)
  --mirror                       (No value)
  --order-by                     Query_time:sum
  --outliers                     Query_time:1:10
  --password                     (No value)
  --pid                          (No value)
  --port                         (No value)
  --print                        FALSE
  --processlist                  (No value)
  --report                       TRUE
  --report-all                   FALSE
  --report-format                header,profile,query_report,rusage
  --review                       (No value)
  --review-history               (No value)
  --run-time                     (No value)
  --sample                       (No value)
  --select                       
  --set-vars                     wait_timeout=10000
  --shorten                      1024
  --since                        (No value)
  --socket                       (No value)
  --tcpdump-errors               (No value)
  --timeline                     FALSE
  --type                         slowlog
  --until                        (No value)
  --user                         (No value)
  --version                      FALSE
  --watch-server                 (No value)
  --zero-admin                   TRUE
  --zero-bool                    FALSE
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