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  • mysql常用配置注意项与sql优化

    建立数据库:

      • 建立数据库时编码字符集采用utf8
      • 排序规则:
        • 后缀"_cs"或者"_ci"意思是区分大小写和不区分大小写(Case Sensitive & Case Insensitve)
        • 后缀"_bin" 规定每个字符串用二进制编码存储,区分大小写,可以直接存储二进制的内容
        • utf-8有默认的排序规则: 命令:SHOW CHARSET LIKE 'utf8%';
        • 注意点:什么时候需要区分大小写需要在设计和使用时注意

        • 如果排序规则使用的是不区分大小写,但部分表字段需要区分大小写,则可以对该字段进行修改:
          ALTER TABLE yourTableName MODIFY COLUMN columnName VARCHAR(255) BINARY CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL;

    建表:

      常见表字段选择请参考其它

      表建立完成后,可以插入一定量的,和业务真实基本一致的数据后,通过执行

    SELECT * FROM yourTableName PROCEDURE ANALYSE(); 

      根据建议修改表字段定义

      注意:此处建议知识针对表中数据,请合理取舍

    测试环境 设置:

      模拟真实场景数据,放大 xxx 倍,作为上线一段时间后的业务数据预期值

    • 统计数据量以配置缓冲区大小
      • #统计指定库表的行数和数据量大小
        select TABLE_SCHEMA as DB_NAME,TABLE_NAME,TABLE_ROWS,DATA_LENGTH
        from information_schema.TABLES
        where table_schema='bdjc_ls'          #指定具体的库名
        -- AND table_name='t_syxm';            #指定具体表名
        ORDER BY DATA_LENGTH DESC
        #统计整个mysql数据量大小  
        select
        concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as ALL_DB_DATA_SIZE,
        concat(round(sum(INDEX_LENGTH/1024/1024),2),'MB') as ALL_DB_INDEX_SIZE,
        concat(round(sum((DATA_LENGTH + INDEX_LENGTH)/1024/1024),2),'MB') as ALL_DB_TOTAL_SIZE
        from information_schema.TABLES;
        #查询全部库或者指定库数据量大小
        select
        table_schema as DB_NAME,
        concat(round(sum(DATA_LENGTH/1024/1024),2),'MB') as DB_DATA_SIZE,
        concat(round(sum(INDEX_LENGTH/1024/1024),2),'MB') as DB_INDEX_SIZE,
        concat(round(sum((DATA_LENGTH + INDEX_LENGTH)/1024/1024),2),'MB') as DB_TOTAL_SIZE
        from information_schema.TABLES
        where table_schema='bdjc_ls'          #指定具体的库名
        AND table_name='t_syxm';            #指定具体表名
        group by table_schema
        order by sum(DATA_LENGTH + INDEX_LENGTH) desc ;
    • #主表数据和索引数据的最大内存缓冲区,分配过大,会使Swap占用过多,致使Mysql的查询特慢
      SELECT @@innodb_buffer_pool_size;  

      #windows下可以修改my.ini文件进行设置,默认为8M my.ini文件可以通过 select @@datadir 找到数据根路径, 然后在data上层目录中会发现my.ini
      在[mysqld] 下进行修改,包括常见的端口,慢查询等各类参数,注意不要超过最大值

      比如我的电脑上文件配置为:

      # InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and
      # row data. The bigger you set this the less disk I/O is needed to
      # access data in tables. On a dedicated database server you may set this
      # parameter up to 80% of the machine physical memory size. Do not set it
      # too large, though, because competition of the physical memory may
      # cause paging in the operating system. Note that on 32bit systems you
      # might be limited to 2-3.5G of user level memory per process, so do not
      # set it too high.
      innodb_buffer_pool_size=3G

      #linux下通过mysql --help|grep 'my.cnf' 查找配置文件,优先使用考前的, 一般为/etc/my.cnf

      设置的innodb_buffer_pool_size 需要为 innodb_buffer_pool_chunk_size*innodb_buffer_pool_instances 的倍数,
      如果不是倍数,设置的innodb_buffer_pool_size会自动调整为倍数
      innodb_buffer_pool_chunk_size是一个只读值, 当innodb_buffer_pool_size大于1G时,就应该将innodb_buffer_pool_instances值调大
      

      #查看设置是否合理
      #Performance = innodb_buffer_pool_reads / innodb_buffer_pool_read_requests * 100
      show status like 'innodb_buffer_pool_read%';

      如果Performance百分比很小,则表示够用

      参考 https://www.cnblogs.com/wanbin/p/9530833.html

      执行
      show engine innodb status
      查看 Free buffers 大小,如果长时间很大,则可以调小innodb_buffer_pool_size,否则可以适当调大innodb_buffer_pool_size
      
      
      命中率 = innodb_buffer_pool_read_requests / (innodb_buffer_pool_read_requests + innodb_buffer_pool_reads ) * 100
      
      如果命中率低于99%,则可以考虑增加innodb_buffer_pool_size
    • 开启慢查询
      • =============开启慢查询========================
        vi /etc/my.cnf
        [mysqld]
        …
        slow_query_log = 1                                         #无效(0或者OFF)、有效(1或者ON)
        slow_query_log_file = /data/log/mysql/slow_query.log      #指定日志文件
        long_query_time = 0.5                                    #超过指定时间的SQL会记录到日志文件(默认时间为10秒,默认单位为秒)
        
        #或者全局设置
        -----------------
        set global slow_query_log = 1;
        set global slow_query_log_file = '/data/log/mysql/slow_query.log';
        set global long_query_time = 0.5;
        #记录sql执行日志
        SET GLOBAL general_log=1
        SET GLOBAL log_output='FILE';
        mysqldumpslow 慢日志分析工具 
        命令:
        
        -s 按照那种方式排序
            c:访问计数
            l:锁定时间
            r:返回记录
            al:平均锁定时间
            ar:平均访问记录数
            at:平均查询时间
        -t 是top n的意思,返回多少条数据。
        -g 可以跟上正则匹配模式,大小写不敏感。
        
        
        #得到返回记录最多的20个sql
        mysqldumpslow -s r -t 20 /data/log/mysql/slow_query.log
        
        #得到平均访问次数最多的20条sql
        mysqldumpslow -s ar -t 20 /data/log/mysql/slow_query.log
        
        #得到平均访问次数最多,并且里面含有ttt字符的20条sql
        mysqldumpslow -s ar -t 20 -g "ttt" /data/log/mysql/slow_query.log
        
        如果出现如下错误,Died at /usr/bin/mysqldumpslow line 161, <> chunk 405659.说明要分析的sql日志太大了,请拆分后再分析
        拆分的命令为:
        tail -10000 /data/log/mysql/slow_query.log>/data/log/mysql/slow_query_1_10000.log
      • 可以通过explain 解析执行对应的慢查询,通过调整表结构、调整索引、查询语句等常规方式优化查询
    • mysql性能压力测试 mysqlslap
      • mysqlslap -h192.168.0.200 -P3306 -uroot -p123456 --number-char-cols=5 --number-int-cols=3 --concurrency=1 --iterations=1 --auto-generate-sql --auto-generate-sql-load-type=mixed --auto-generate-sql-add-autoincrement --engine=innodb,myisam --number-of-queries=1 --auto-generate-sql-write-number=1 --only-print 
        
        mysqlslap -h192.168.0.200 -P3306 -uroot -p123456 --concurrency=100,500,1000 --iterations=1 --auto-generate-sql --auto-generate-sql-load-type=mixed --auto-generate-sql-add-autoincrement --engine=innodb --number-of-queries=5000
        
        mysqlslap -h192.168.0.200 -P3306 -uroot -p123456 --concurrency=2 --iterations=2 --create-schema=mysql --query="select * from user" --engine=innodb --number-of-queries=20
        
        mysqlslap -h192.168.0.200 -P3306 -uroot -p123456 --concurrency=100 --iterations=1 --create-schema=mysql --query=/root/mysql/query.sql --engine=innodb --number-of-queries=5000
        --print-defaults        Print the program argument list and exit.
        --no-defaults           Don't read default options from any option file,
                                except for login file.
        --defaults-file=#       Only read default options from the given file #.
        --defaults-extra-file=# Read this file after the global files are read.
        --defaults-group-suffix=#
                                Also read groups with concat(group, suffix)
        --login-path=#          Read this path from the login file.
          -?, --help            Display this help and exit.
          -a, --auto-generate-sql
                              Generate SQL where not supplied by file or command line.
          --auto-generate-sql-add-autoincrement
                              Add an AUTO_INCREMENT column to auto-generated tables.
          --auto-generate-sql-execute-number=#
                              Set this number to generate a set number of queries to run.
          --auto-generate-sql-guid-primary
                              Add GUID based primary keys to auto-generated tables.
          --auto-generate-sql-load-type=name  
                              Specify test load type: mixed, update, write, key, or read; default is mixed.
          --auto-generate-sql-secondary-indexes=#
                              Number of secondary indexes to add to auto-generated
                              tables.
          --auto-generate-sql-unique-query-number=#
                              Number of unique queries to generate for automatic tests.
          --auto-generate-sql-unique-write-number=#
                              Number of unique queries to generate for auto-generate-sql-write-number.
          --auto-generate-sql-write-number=#
                              Number of row inserts to perform for each thread (default is 100).
          --commit=#          Commit records every X number of statements.
          -C, --compress      Use compression in server/client protocol.
          -c, --concurrency=name
                              Number of clients to simulate for query to run.
          --create=name       File or string to use create tables.
          --create-schema=name
                              Schema to run tests in.
          --csv[=name]        Generate CSV output to named file or to stdout if no file is named.
          -#, --debug[=#]     This is a non-debug version. Catch this and exit.
          --debug-check       This is a non-debug version. Catch this and exit.
          -T, --debug-info    This is a non-debug version. Catch this and exit.
          --default-auth=name Default authentication client-side plugin to use.
          -F, --delimiter=name
                              Delimiter to use in SQL statements supplied in file or command line.
          --detach=#          Detach (close and reopen) connections after X number of requests.
          --enable-cleartext-plugin
                              Enable/disable the clear text authentication plugin.
          -e, --engine=name   Storage engine to use for creating the table.
          -h, --host=name     Connect to host.
          -i, --iterations=#  Number of times to run the tests.
          --no-drop           Do not drop the schema after the test.
          -x, --number-char-cols=name
                              Number of VARCHAR columns to create in table if specifying --auto-generate-sql.
          -y, --number-int-cols=name
                              Number of INT columns to create in table if specifying --auto-generate-sql.
          --number-of-queries=#
                              Limit each client to this number of queries (this is not exact).
          --only-print        Do not connect to the databases, but instead print out what would have been done.
          -p, --password[=name]
                              Password to use when connecting to server. If password is not given it's asked from the tty.
          -W, --pipe          Use named pipes to connect to server.
          --plugin-dir=name   Directory for client-side plugins.
          -P, --port=#        Port number to use for connection.
          --post-query=name   Query to run or file containing query to execute after
                              tests have completed.
          --post-system=name  system() string to execute after tests have completed.
          --pre-query=name    Query to run or file containing query to execute before
                              running tests.
          --pre-system=name   system() string to execute before running tests.
          --protocol=name     The protocol to use for connection (tcp, socket, pipe,
                              memory).
          -q, --query=name    Query to run or file containing query to run.
          --secure-auth       Refuse client connecting to server if it uses old
                              (pre-4.1.1) protocol. Deprecated. Always TRUE
          --shared-memory-base-name=name
                              Base name of shared memory.
          -s, --silent        Run program in silent mode - no output.
          -S, --socket=name   The socket file to use for connection.
          --sql-mode=name     Specify sql-mode to run mysqlslap tool.
          --ssl-mode=name     SSL connection mode.
          --ssl               Deprecated. Use --ssl-mode instead.
                              (Defaults to on; use --skip-ssl to disable.)
          --ssl-verify-server-cert
                              Deprecated. Use --ssl-mode=VERIFY_IDENTITY instead.
          --ssl-ca=name       CA file in PEM format.
          --ssl-capath=name   CA directory.
          --ssl-cert=name     X509 cert in PEM format.
          --ssl-cipher=name   SSL cipher to use.
          --ssl-key=name      X509 key in PEM format.
          --ssl-crl=name      Certificate revocation list.
          --ssl-crlpath=name  Certificate revocation list path.
          --tls-version=name  TLS version to use, permitted values are: TLSv1, TLSv1.1
          -u, --user=name     User for login if not current user.
          -v, --verbose       More verbose output; you can use this multiple times to
                              get even more verbose output.
          -V, --version       Output version information and exit.
        mysqlslap参数一览
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  • 原文地址:https://www.cnblogs.com/xiaochangwei/p/10818548.html
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