• 2015-09-18

    MySQL binlog查看和清理

    Views: 6011 | No Comments

    显示 binlog 文件列表

    show binary logs;
    

    清理 binlog 文件

    purge binary logs to 'mysql-bin.000001';
    

    查看 binlog 内容

    show binlog events in 'mysql-bin.000001' limit 1000, 10;
    

    或者SHELL命令行

    sudo mysqlbinlog mysql-bin.000001
    
    Posted by ideawu at 2015-09-18 17:08:42 Tags:
  • 2012-03-01

    MySQL 基本配置

    Views: 11975 | No Comments

    query_cache_size, tmp_table_size 这两个选项一定要设置!

    # The following options will be passed to all MySQL clients
    [client]
    #password	= your_password
    port		= 3306
    socket		= /home/work/mysql/tmp/mysql.sock
    
    # Here follows entries for some specific programs
    
    # The MySQL server
    [mysqld]
    port		= 3306
    bind-address = 127.0.0.1
    socket		= /home/work/mysql/tmp/mysql.sock
    #skip-locking
    max_allowed_packet = 1M
    table_open_cache = 16
    sort_buffer_size = 8M
    read_buffer_size = 512K
    read_rnd_buffer_size = 256K
    net_buffer_length = 8K
    thread_stack = 128K
    
    # Size of the Key Buffer, used to cache index blocks for MyISAM tables.
    # Do not set it larger than 30% of your available memory, as some memory
    # is also required by the OS to cache rows. Even if you're not using
    # MyISAM tables, you should still set it to 8-64M as it will also be
    # used for internal temporary disk tables.
    key_buffer_size = 8M
    
    # If the temporary file used for fast index creation would be bigger
    # than using the key cache by the amount specified here, then prefer the
    # key cache method.  This is mainly used to force long character keys in
    # large tables to use the slower key cache method to create the index.
    myisam_sort_buffer_size = 8M
    
    # Query cache is used to cache SELECT results and later return them
    # without actual executing the same query once again. Having the query
    # cache enabled may result in significant speed improvements, if your
    # have a lot of identical queries and rarely changing tables. See the
    # "Qcache_lowmem_prunes" status variable to check if the current value
    # is high enough for your load.
    # Note: In case your tables change very often or if your queries are
    # textually different every time, the query cache may result in a
    # slowdown instead of a performance improvement.
    query_cache_size=16M
    
    # Maximum size for internal (in-memory) temporary tables. If a table
    # grows larger than this value, it is automatically converted to disk
    # based table This limitation is for a single table. There can be many
    # of them.
    tmp_table_size=16M
    
    
    # Don't listen on a TCP/IP port at all. This can be a security enhancement,
    # if all processes that need to connect to mysqld run on the same host.
    # All interaction with mysqld must be made via Unix sockets or named pipes.
    # Note that using this option without enabling named pipes on Windows
    # (using the "enable-named-pipe" option) will render mysqld useless!
    # 
    skip-networking
    server-id	= 1
    
    # Uncomment the following if you want to log updates
    #log-bin=mysql-bin
    
    # binary logging format - mixed recommended
    #binlog_format=mixed
    
    # Uncomment the following if you are using InnoDB tables
    #default_storage_engine=InnoDB
    
    innodb_data_home_dir = /home/work/mysql/var/
    innodb_data_file_path = ibdata1:10M:autoextend
    innodb_log_group_home_dir = /home/work/mysql/var/
    # You can set .._buffer_pool_size up to 50 - 80 %
    # of RAM but beware of setting memory usage too high
    innodb_buffer_pool_size = 32M
    innodb_additional_mem_pool_size = 4M
    # Set .._log_file_size to 25 % of buffer pool size
    innodb_log_file_size = 10M
    innodb_log_buffer_size = 16M
    innodb_flush_log_at_trx_commit = 1
    innodb_lock_wait_timeout = 50
    
    [mysqldump]
    quick
    max_allowed_packet = 16M
    
    [mysql]
    no-auto-rehash
    # Remove the next comment character if you are not familiar with SQL
    #safe-updates
    
    [myisamchk]
    key_buffer_size = 8M
    sort_buffer_size = 8M
    
    [mysqlhotcopy]
    interactive-timeout
    
    Posted by ideawu at 2012-03-01 10:41:23 Tags:
  • 2011-06-24

    关系数据库应用设计基础

    Views: 24747 | 1 Comment

    这是我给部门同事做的技术分享.

    当今绝大部分的软件系统都用到了关系数据库, 所以, 作为软件开发工程师, 必须掌握关系数据库应用设计能力.

    Posted by ideawu at 2011-06-24 18:02:57 Tags:
  • 2011-05-21

    MySQL”海量数据”查询性能分析

    Views: 20835 | 2 Comments

    最近做了一次MySQL所谓的"海量数据"查询性能分析.

    表结构

    dt dt2 dt3 it it2 it3
    id id id id id id int PK
    ext1 ext1 varchar(256)
    time time time time time time int/datetime KEY
    ext2 ext2 ext2 ext2 varchar(128)

    说明, MyISAM引擎, dt表示时间字段使用datetime类型, it表示时间字段使用int类型.

    初始数据

    首先生成100K个UNIX时间戳(int), 然后随机选取10M次, 每一次往6个表里插入一条记录(当time字段是datetime类型时, 做类型转换). 所以每一个表都有10M条记录. ext1和ext2字段会用随机的字符串填充.

    Continue reading »

    Posted by ideawu at 2011-05-21 10:18:05 Tags:
  • 2009-12-29

    Linux下编译安装Apache/Nginx/Lighttpd+PHP+MySQL

    Views: 24632 | 1 Comment

    使用Ubuntu Linux, 编译过程提示缺啥补啥即可.

    Apache:

    ./configure --prefix=/home/work/httpd --enable-so --enable-rewrite --enable-vhost-alias
    

    配置文件:

    LoadModule php5_module        modules/libphp5.so
    AddType application/x-httpd-php .php
    # PhpIniDir /home/work/php/php.ini
    

    MYSQL:

    Continue reading »

    Posted by ideawu at 2009-12-29 11:32:25 Tags: ,
  • 2009-11-23

    数据库字段设计错误导致的系统BUG

    Views: 15304 | No Comments

    Yii的AR类, 可以在rules()函数中声明验证规则. 但指定了验证规则, 也可以不使用. 在调用save()方法时, 如何第一个参数为false(默认为true), 则不进行验证. 一旦验证失败, 将立即返回, 不保存数据. Yii提供的工具可以根据数据库表定义自动生成验证规则. AR类的验证规则的另一个功能是用于自动生成HTML页面表单. 但是, 根据实际使用情况, Yii所提供的这个功能在XXX项目中几乎已经成为鸡肋, 都是在开发者不知情的情况下使用了.

    Yii的这个特性, 加上数据库表设计的失误, 以及代码逻辑问题, 导致某个功能出现BUG.

    代码的功能是这样的: 调用AR类的save()方法保存一条记录, 然后跳转到该记录的详细信息页面. 实际操作时, 偶尔出现记录未保存, 然后跳转URL里的id参数为空. 代码逻辑如下:

    if($ar->save()){
        // do something
    }
    redirect($ar->id);
    

    显然, 代码逻辑没有错误处理, 无论成功与否, 都跳转. 下面再分析保存失败的原因.

    数据库表定义中, 备注字段的类型为VARCHAR(255), 如何短的字符串类型的应用范围一般很窄, 再加上所对应的业务字段是备注信息, 往往是大段的文本, 所以, 数据库设计已经失败, 出错是必然的. 另外, 程序逻辑无论是客户端还是服务器端, 都没有再做业务层的验证给出错误提示, 而是无意地使用了Yii框架的AR类的验证机制. 综合上述原因, BUG的查找花费了不少的时间.

    总结:

    1. 数据库设计

    通过对数据库表字段的仔细选择来获取性能, 对于XXX系统, 这种方式已经过时. 一般只有如下几种数据类型: 数字, 字符串(varchar), 文本(长字符串, text), 时间.

    结合 MySQL, 数字主要使用int, 像tiny int, middle int之类的整数类型, 只是节省空间考虑, 速度上反而比int类型要慢, 当数值较大时, 使用bigint. 对XXX, 除了int和bigint, 其它的整数类型都没有必要.

    对于字符串和文本类型, 如果不建立索引作为查询条件, 一般使用text, 不要使用varchar, 如果文本较长, 则使用longtext. 如果字段对应的输入框是多行文本框, 那么就没有使用varchar的必要了. 建议原则是: 不建立索引的字符串使用text, 格式化输入框(HTML编辑控件)对应的字段使用longtext, 只有建立索引的字符串才使用varchar.

    2. AR类设计

    把AR类中的rules()函数删除.

    3. 客户端验证

    在客户端也做验证, 并在出错时提示用户. 如用户输入的文本过长, 等等.

    Posted by ideawu at 2009-11-23 16:58:12 Tags:
|<<<12>>>| 1/2 Pages, 7 Results.