下面允许我介绍一下MySQL的my.ini配置文件：
my.ini是什么？
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。
my.ini存放在哪里？
my.ini存放在MySql安装的根目录，如图所示：
my.ini的具体内容介绍：
1 # CLIENT SECTION 2 # ---------------------------------------------------------------------- 3 # 4 # The following options will be read by MySQL client applications. 5 # Note that only client applications shipped by MySQL are guaranteed 6 # to read this section. If you want your own MySQL client program to 7 # honor these values, you need to specify it as an option during the 8 # MySQL client library initialization. 9 # 10 [client] 11 12 port=3306 13 14 [mysql] 15 16 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
1 # SERVER SECTION 2 # ---------------------------------------------------------------------- 3 # 4 # The following options will be read by the MySQL Server. Make sure that 5 # you have installed the server correctly (see above) so it reads this 6 # file. 7 # 8 [mysqld] 9 10 # The TCP/IP Port the MySQL Server will listen on 11 port=3306 12 13 14 #Path to installation directory. All paths are usually resolved relative to this. 15 basedir="E:/Java/Mysql/" 16 17 #Path to the database root 18 datadir="C:/ProgramData/MySQL/MySQL Server 5.5/Data/" 19 20 # The default character set that will be used when a new schema or table is 21 # created and no character set is defined 22 character-set-server=gb2312 23 24 # The default storage engine that will be used when create new tables when 25 default-storage-engine=INNODB 26 27 # Set the SQL mode to strict 28 sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" 29 30 # The maximum amount of concurrent sessions the MySQL server will 31 # allow. One of these connections will be reserved for a user with 32 # SUPER privileges to allow the administrator to login even if the 33 # connection limit has been reached. 34 max_connections=100 35 36 # Query cache is used to cache SELECT results and later return them 37 # without actual executing the same query once again. Having the query 38 # cache enabled may result in significant speed improvements, if your 39 # have a lot of identical queries and rarely changing tables. See the 40 # "Qcache_lowmem_prunes" status variable to check if the current value 41 # is high enough for your load. 42 # Note: In case your tables change very often or if your queries are 43 # textually different every time, the query cache may result in a 44 # slowdown instead of a performance improvement. 45 query_cache_size=0 46 47 # The number of open tables for all threads. Increasing this value 48 # increases the number of file descriptors that mysqld requires. 49 # Therefore you have to make sure to set the amount of open files 50 # allowed to at least 4096 in the variable "open-files-limit" in 51 # section [mysqld_safe] 52 table_cache=256 53 54 # Maximum size for internal (in-memory) temporary tables. If a table 55 # grows larger than this value, it is automatically converted to disk 56 # based table This limitation is for a single table. There can be many 57 # of them. 58 tmp_table_size=35M 59 60 61 # How many threads we should keep in a cache for reuse. When a client 62 # disconnects, the client's threads are put in the cache if there aren't 63 # more than thread_cache_size threads from before. This greatly reduces 64 # the amount of thread creations needed if you have a lot of new 65 # connections. (Normally this doesn't give a notable performance 66 # improvement if you have a good thread implementation.) 67 thread_cache_size=8 68 69 #*** MyISAM Specific options 70 71 # The maximum size of the temporary file MySQL is allowed to use while 72 # recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE. 73 # If the file-size would be bigger than this, the index will be created 74 # through the key cache (which is slower). 75 myisam_max_sort_file_size=100G 76 77 # If the temporary file used for fast index creation would be bigger 78 # than using the key cache by the amount specified here, then prefer the 79 # key cache method. This is mainly used to force long character keys in 80 # large tables to use the slower key cache method to create the index. 81 myisam_sort_buffer_size=69M 82 83 # Size of the Key Buffer, used to cache index blocks for MyISAM tables. 84 # Do not set it larger than 30% of your available memory, as some memory 85 # is also required by the OS to cache rows. Even if you're not using 86 # MyISAM tables, you should still set it to 8-64M as it will also be 87 # used for internal temporary disk tables. 88 key_buffer_size=55M 89 90 # Size of the buffer used for doing full table scans of MyISAM tables. 91 # Allocated per thread, if a full scan is needed. 92 read_buffer_size=64K 93 read_rnd_buffer_size=256K 94 95 # This buffer is allocated when MySQL needs to rebuild the index in 96 # REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE 97 # into an empty table. It is allocated per thread so be careful with 98 # large settings. 99 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
1 #*** INNODB Specific options *** 2 3 4 # Use this option if you have a MySQL server with InnoDB support enabled 5 # but you do not plan to use it. This will save memory and disk space 6 # and speed up some things. 7 #skip-innodb 8 9 # Additional memory pool that is used by InnoDB to store metadata 10 # information. If InnoDB requires more memory for this purpose it will 11 # start to allocate it from the OS. As this is fast enough on most 12 # recent operating systems, you normally do not need to change this 13 # value. SHOW INNODB STATUS will display the current amount used. 14 innodb_additional_mem_pool_size=3M 15 16 # If set to 1, InnoDB will flush (fsync) the transaction logs to the 17 # disk at each commit, which offers full ACID behavior. If you are 18 # willing to compromise this safety, and you are running small 19 # transactions, you may set this to 0 or 2 to reduce disk I/O to the 20 # logs. Value 0 means that the log is only written to the log file and 21 # the log file flushed to disk approximately once per second. Value 2 22 # means the log is written to the log file at each commit, but the log 23 # file is only flushed to disk approximately once per second. 24 innodb_flush_log_at_trx_commit=1 25 26 # The size of the buffer InnoDB uses for buffering log data. As soon as 27 # it is full, InnoDB will have to flush it to disk. As it is flushed 28 # once per second anyway, it does not make sense to have it very large 29 # (even with long transactions). 30 innodb_log_buffer_size=2M 31 32 # InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and 33 # row data. The bigger you set this the less disk I/O is needed to 34 # access data in tables. On a dedicated database server you may set this 35 # parameter up to 80% of the machine physical memory size. Do not set it 36 # too large, though, because competition of the physical memory may 37 # cause paging in the operating system. Note that on 32bit systems you 38 # might be limited to 2-3.5G of user level memory per process, so do not 39 # set it too high. 40 innodb_buffer_pool_size=107M 41 42 # Size of each log file in a log group. You should set the combined size 43 # of log files to about 25%-100% of your buffer pool size to avoid 44 # unneeded buffer pool flush activity on log file overwrite. However, 45 # note that a larger logfile size will increase the time needed for the 46 # recovery process. 47 innodb_log_file_size=54M 48 49 # Number of threads allowed inside the InnoDB kernel. The optimal value 50 # depends highly on the application, hardware as well as the OS 51 # scheduler properties. A too high value may lead to thread thrashing. 52 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。
注意：每次修改参数后，必须重新启动MySQL服务才会有效。
