查看mysql日志

查看mysql查询日志

MySQL的日志操作：

1. 确认是否启用日志

   登陆mysql后，执行sql语句：show variables like 'log_bin';

   mysql> show variables like 'log_bin';
   +---------------+-------+
   | Variable_name | Value |
   +---------------+-------+
   | log_bin       | OFF   |
   +---------------+-------+
   1 row in set (0.00 sec)            
   

   当前未启用日志。如果Value值为ON，则已启用日志。日志文件在mysql的安装目录的data目录下。
   查看当前日志：mysql> show master status;

2. 查询日志：log

   开启方式：在my.ini的[mysqld]选项下，添加代码：
   log=C:/backend/MySQL/MySQL Server 5.5/log.txt

3. 错误日志：log-error

   开启方式：在my.ini的[mysqld]选项下，添加代码：
   log-error=C:/backend/MySQL/MySQL Server 5.5/log-error.txt

4. 二进制日志：log-bin

   开启方式：在my.ini的[mysqld]选项下，添加代码：
   log-bin=C:/backend/MySQL/MySQL Server 5.5/log-bin

5. 重启mysql服务

   以管理员身份运行cmd,输入：

   C:Windowssystem32>net stop mysql
   The MySQL service is stopping.
   The MySQL service was stopped successfully.
   
   C:Windowssystem32>net start mysql
   The MySQL service is starting.
   The MySQL service was started successfully.
   

MySQL的配置文件：my.ini

1. my.ini的作用

   my.ini是MySQL数据库中使用的配置文件，修改这个文件可以达到更新配置的目的。

2. 查找 my.ini 的位置

   my.ini存放在MySql安装的根目录。

忘记安装目录时，可通过sql语句查看安装目录。mysql> select @@basedir;

3. my.ini的具体内容介绍：

   # CLIENT SECTION
   # ----------------------------------------------------------------------
   #
   # The following options will be read by MySQL client applications.
   # Note that only client applications shipped by MySQL are guaranteed
   # to read this section. If you want your own MySQL client program to
   # honor these values, you need to specify it as an option during the
   # MySQL client library initialization.
   #
   [client]
   
   port=3306
   
   [mysql]
   
   default-character-set=gb2312
   

   上面显示的是客户端的参数，[client]和[mysql]都是客户端，下面是参数简介：

   　　1.port参数表示的是MySQL数据库的端口，默认的端口是3306，如果你需要更改端口号的话，就可以通过在这里修改。

   　　2.default-character-set参数是客户端默认的字符集，如果你希望它支持中文，可以设置成gbk或者utf8。

   　　3.这里还有一个password参数，在这里设置了password参数的值就可以在登陆时不用输入密码直接进入

   # SERVER SECTION
   # ----------------------------------------------------------------------
   #
   # The following options will be read by the MySQL Server. Make sure that
   # you have installed the server correctly (see above) so it reads this 
   # file.
   #
   [mysqld]
   
   # The TCP/IP Port the MySQL Server will listen on
   port=3306
   
   
   #Path to installation directory. All paths are usually resolved relative to this.
   basedir="E:/Java/Mysql/"
   
   #Path to the database root
   datadir="C:/ProgramData/MySQL/MySQL Server 5.5/Data/"
   
   # The default character set that will be used when a new schema or table is
   # created and no character set is defined
   character-set-server=gb2312
   
   # The default storage engine that will be used when create new tables when
   default-storage-engine=INNODB
   
   # Set the SQL mode to strict
   sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
   
   # The maximum amount of concurrent sessions the MySQL server will
   # allow. One of these connections will be reserved for a user with
   # SUPER privileges to allow the administrator to login even if the
   # connection limit has been reached.
   max_connections=100
   
   # 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=0
   
   # The number of open tables for all threads. Increasing this value
   # increases the number of file descriptors that mysqld requires.
   # Therefore you have to make sure to set the amount of open files
   # allowed to at least 4096 in the variable "open-files-limit" in
   # section [mysqld_safe]
   table_cache=256
   
   # 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=35M
   
   
   # How many threads we should keep in a cache for reuse. When a client
   # disconnects, the client's threads are put in the cache if there aren't
   # more than thread_cache_size threads from before.  This greatly reduces
   # the amount of thread creations needed if you have a lot of new
   # connections. (Normally this doesn't give a notable performance
   # improvement if you have a good thread implementation.)
   thread_cache_size=8
   
   #*** MyISAM Specific options
   
   # The maximum size of the temporary file MySQL is allowed to use while
   # recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE.
   # If the file-size would be bigger than this, the index will be created
   # through the key cache (which is slower).
   myisam_max_sort_file_size=100G
   
   # 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=69M
   
   # 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=55M
   
   # Size of the buffer used for doing full table scans of MyISAM tables.
   # Allocated per thread, if a full scan is needed.
   read_buffer_size=64K
   read_rnd_buffer_size=256K
   
   # This buffer is allocated when MySQL needs to rebuild the index in
   # REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE
   # into an empty table. It is allocated per thread so be careful with
   # large settings.
   sort_buffer_size=256K
   

   上面是服务器断参数，一下是参数的简介：

   　　1.port参数也是表示数据库的端口。

   　　2.basedir参数表示MySQL的安装路径。

   　　3.datadir参数表示MySQL数据文件的存储位置，也是数据库表的存放位置。

   　　4.default-character-set参数表示默认的字符集，这个字符集是服务器端的。

   　　5.default-storage-engine参数默认的存储引擎。

   　　6.sql-mode参数表示SQL模式的参数，通过这个参数可以设置检验SQL语句的严格程度。

   　　7.max_connections参数表示允许同时访问MySQL服务器的最大连接数，其中一个连接是保留的，留给管理员专用的。

   　　8.query_cache_size参数表示查询时的缓存大小，缓存中可以存储以前通过select语句查询过的信息，再次查询时就可以直接从缓存中拿出信息。

   　　9.table_cache参数表示所有进程打开表的总数。

   　　10.tmp_table_size参数表示内存中临时表的总数。

   　　11.thread_cache_size参数表示保留客户端线程的缓存。

   　　12.myisam_max_sort_file_size参数表示MySQL重建索引时所允许的最大临时文件的大小。

   　　13.myisam_sort_buffer_size参数表示重建索引时的缓存大小。

   　　14.key_buffer_size参数表示关键词的缓存大小。

   　　15.read_buffer_size参数表示MyISAM表全表扫描的缓存大小。

   　　16.read_rnd_buffer_size参数表示将排序好的数据存入该缓存中。

   　　17.sort_buffer_size参数表示用于排序的缓存大小

   #*** INNODB Specific options ***
   
   
   # Use this option if you have a MySQL server with InnoDB support enabled
   # but you do not plan to use it. This will save memory and disk space
   # and speed up some things.
   #skip-innodb
   
   # Additional memory pool that is used by InnoDB to store metadata
   # information.  If InnoDB requires more memory for this purpose it will
   # start to allocate it from the OS.  As this is fast enough on most
   # recent operating systems, you normally do not need to change this
   # value. SHOW INNODB STATUS will display the current amount used.
   innodb_additional_mem_pool_size=3M
   
   # If set to 1, InnoDB will flush (fsync) the transaction logs to the
   # disk at each commit, which offers full ACID behavior. If you are
   # willing to compromise this safety, and you are running small
   # transactions, you may set this to 0 or 2 to reduce disk I/O to the
   # logs. Value 0 means that the log is only written to the log file and
   # the log file flushed to disk approximately once per second. Value 2
   # means the log is written to the log file at each commit, but the log
   # file is only flushed to disk approximately once per second.
   innodb_flush_log_at_trx_commit=1
   
   # The size of the buffer InnoDB uses for buffering log data. As soon as
   # it is full, InnoDB will have to flush it to disk. As it is flushed
   # once per second anyway, it does not make sense to have it very large
   # (even with long transactions).
   innodb_log_buffer_size=2M
   
   # 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=107M
   
   # Size of each log file in a log group. You should set the combined size
   # of log files to about 25%-100% of your buffer pool size to avoid
   # unneeded buffer pool flush activity on log file overwrite. However,
   # note that a larger logfile size will increase the time needed for the
   # recovery process.
   innodb_log_file_size=54M
   
   # Number of threads allowed inside the InnoDB kernel. The optimal value
   # depends highly on the application, hardware as well as the OS
   # scheduler properties. A too high value may lead to thread thrashing.
   innodb_thread_concurrency=18
   

   上面是InnoDB存储引擎使用的参数，一下是参数的简介：

   　　1.innodb_additional_mem_pool_size参数表示附加的内存池，用来存储InnoDB表的内容。

   　　2.innodb_flush_log_at_trx_commit参数是设置提交日志的时机，若设置为1，InnoDB会在每次提交后将事务日志写到磁盘上。

   　　3.innodb_log_buffer_size参数表示用来存储日志数据的缓存区的大小。

   　　4.innodb_buffer_pool_size参数表示缓存的大小，InnoDB使用一个缓冲池类保存索引和原始数据。

   　　5.innodb_log_file_size参数表示日志文件的大小。

   　　6.innodb_thread_concurrency参数表示在InnoDB存储引擎允许的线程最大数。

注：每次修改参数后，必须重新启动MySQL服务才会有效。