很多时候为了测试数据库设计是否恰当,优化SQL语句,需要在表中插入大量的数据,怎么插入大量的数据就是个问题了。 最开始想到的办法就是写一个程序通过一个很大的循环来不停的插入,比如这样: 1 2 3 4 int i = LOOP_COUNT ; while ( i --= 0 ){ //insert d
很多时候为了测试数据库设计是否恰当,优化SQL语句,需要在表中插入大量的数据,怎么插入大量的数据就是个问题了。
最开始想到的办法就是写一个程序通过一个很大的循环来不停的插入,比如这样:
<span>1</span> <span>2</span> <span>3</span> <span>4</span> |
<code><span><span>int</span> <span>i</span> <span>=</span> <span>LOOP_COUNT</span><span>;</span> </span><span><span>while</span><span>(</span><span>i</span><span>-->=</span><span>0</span><span>){</span> </span><span> <span>//insert data here.</span> </span><span><span>}</span> </span></code> |
不过我在这么做的时候发现这样插入数据非常的慢,一秒钟插入的数据量还不到100条,于是想到不要一条一条的插入,而是通过
<span>1</span> |
<code><span>INSERT</span> <span>INTO</span> <span>TABLE</span> <span>VALUES</span> <span>(),(),(),()...</span> </code> |
这样的方式来插入。于是修改程序为:
<span>1</span> <span>2</span> <span>3</span> <span>4</span> 5 6 7 8 9 |
<code><span><span>int</span> <span>i</span> <span>=</span> <span>LOOP_COUNT</span><span>;</span> </span><span><span>StringBuilder</span> <span>stringBuilder</span><span>;</span> </span><span><span>while</span><span>(</span><span>i</span><span>-->=</span><span>0</span><span>){</span> </span><span> <span>if</span><span>(</span><span>LOOP_COUNT</span><span>!=</span><span>i</span> <span>&&</span> <span>i</span><span>%</span><span>5000</span><span>==</span><span>0</span><span>){</span> </span><span> <span>//通过insert values的方式插入这5000条数据并清空stringBuilder</span> </span><span> <span>}</span> </span><span> <span>stringBuilder</span><span>.</span><span>append</span><span>(</span><span>"(数据)"</span><span>);</span> </span><span><span>}</span> </span><span><span>//插入剩余的数据</span> </span></code> |
这样做的插入速度是上升了很多,不过如果想要插入大量的输入,比如上亿条,那么花费的时间还是非常长的。
查询MySQL的文档,发现了一个页面:LOAD DATA INFILE 光看这个名字,觉得有戏,于是仔细看了下。
官方对于这个命令的描述是:
<span>1</span> <span>2</span> <span>3</span> <span>4</span> 5 6 7 8 9 10 11 12 13 14 15 16 |
<code><span><span>LOAD</span> <span>DATA</span> <span>[</span><span>LOW_PRIORITY</span> <span>|</span> <span>CONCURRENT</span><span>]</span> <span>[</span><span>LOCAL</span><span>]</span> <span>INFILE</span> <span>'</span><span>file_name</span><span>'</span> </span><span> <span>[</span><span>REPLACE</span> <span>|</span> <span>IGNORE</span><span>]</span> </span><span> <span>INTO</span> <span>TABLE</span> <span>tbl_name</span> </span><span> <span>[</span><span>CHARACTER</span> <span>SET</span> <span>charset_name</span><span>]</span> </span><span> <span>[{</span><span>FIELDS</span> <span>|</span> <span>COLUMNS</span><span>}</span> </span><span> <span>[</span><span>TERMINATED</span> <span>BY</span> <span>'</span><span>string</span><span>'</span><span>]</span> </span><span> <span>[[</span><span>OPTIONALLY</span><span>]</span> <span>ENCLOSED</span> <span>BY</span> <span>'</span><span>char</span><span>'</span><span>]</span> </span><span> <span>[</span><span>ESCAPED</span> <span>BY</span> <span>'</span><span>char</span><span>'</span><span>]</span> </span><span> <span>]</span> </span><span> <span>[</span><span>LINES</span> </span><span> <span>[</span><span>STARTING</span> <span>BY</span> <span>'</span><span>string</span><span>'</span><span>]</span> </span><span> <span>[</span><span>TERMINATED</span> <span>BY</span> <span>'</span><span>string</span><span>'</span><span>]</span> </span><span> <span>]</span> </span><span> <span>[</span><span>IGNORE</span> <span>number</span> <span>LINES</span><span>]</span> </span><span> <span>[(</span><span>col_name_or_user_var</span><span>,...)]</span> </span><span> <span>[</span><span>SET</span> <span>col_name</span> <span>=</span> <span>expr</span><span>,...]</span> </span></code> |
命令不复杂,具体的每个参数的意义和用法请看官方的解释 http://dev.mysql.com/doc/refman/5.5/en/load-data.html
那么现在做的就是生成数据了,我习惯用t作为数据的分隔符、用n作为一行的分隔符,所以生成数据的代码如下:
<span>1</span> <span>2</span> <span>3</span> <span>4</span> 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 |
<code><span><span>long</span> <span>start</span> <span>=</span> <span>System</span><span>.</span><span>currentTimeMillis</span><span>()</span> <span>/</span> <span>1000</span><span>;</span> </span><span><span>try</span> <span>{</span> </span><span> <span>File</span> <span>file</span> <span>=</span> <span>new</span> <span>File</span><span>(</span><span>FILE</span><span>);</span> </span><span> <span>if</span> <span>(</span><span>file</span><span>.</span><span>exists</span><span>())</span> <span>{</span> </span><span> <span>file</span><span>.</span><span>delete</span><span>();</span> </span><span> <span>}</span> </span><span> <span>file</span><span>.</span><span>createNewFile</span><span>();</span> </span><span> <span>FileOutputStream</span> <span>outStream</span> <span>=</span> <span>new</span> <span>FileOutputStream</span><span>(</span><span>file</span><span>,</span> <span>true</span><span>);</span> </span><span> <span>StringBuilder</span> <span>builder</span> <span>=</span> <span>new</span> <span>StringBuilder</span><span>(</span><span>10240</span><span>);</span> </span><span> <span>DateFormat</span> <span>dateFormat</span> <span>=</span> <span>new</span> <span>SimpleDateFormat</span><span>(</span><span>DATE_FORMAT</span><span>);</span> </span><span> <span>Random</span> <span>rand</span> <span>=</span> <span>new</span> <span>Random</span><span>();</span> </span><span> <span>String</span> <span>tmpDate</span> <span>=</span> <span>dateFormat</span><span>.</span><span>format</span><span>(</span><span>new</span> <span>Date</span><span>());</span> </span><span> <span>Long</span> <span>tmpTimestamp</span> <span>=</span> <span>System</span><span>.</span><span>currentTimeMillis</span><span>()</span> <span>/</span> <span>1000</span><span>;</span> </span><span> <span>int</span> <span>i</span> <span>=</span> <span>0</span><span>;</span> </span><span> <span>while</span> <span>(</span><span>i</span><span>++</span> <span> <span>LOOP</span><span>)</span> <span>{</span> </span><span> <span>if</span> <span>(</span><span>i</span> <span>></span> <span>0</span> <span>&&</span> <span>i</span> <span>%</span> <span>30000</span> <span>==</span> <span>0</span><span>)</span> <span>{</span> </span><span> <span>System</span><span>.</span><span>out</span><span>.</span><span>println</span><span>(</span><span>"write offset:"</span> <span>+</span> <span>i</span><span>);</span> </span><span> <span>outStream</span><span>.</span><span>write</span><span>(</span><span>builder</span><span>.</span><span>toString</span><span>().</span><span>getBytes</span><span>(</span><span>CHARCODE</span><span>));</span> </span><span> <span>builder</span> <span>=</span> <span>new</span> <span>StringBuilder</span><span>(</span><span>10240</span><span>);</span> </span><span> <span>}</span> </span><span> <span>if</span> <span>(</span><span>tmpTimestamp</span><span>.</span><span>compareTo</span><span>(</span><span>System</span><span>.</span><span>currentTimeMillis</span><span>()</span> <span>/</span> <span>1000</span><span>)</span> <span>!=</span> <span>0</span><span>)</span> <span>{</span> </span><span> <span>tmpDate</span> <span>=</span> <span>dateFormat</span><span>.</span><span>format</span><span>(</span><span>new</span> <span>Date</span><span>());</span> </span><span> <span>tmpTimestamp</span> <span>=</span> <span>System</span><span>.</span><span>currentTimeMillis</span><span>()</span> <span>/</span> <span>1000</span><span>;</span> </span><span> <span>}</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>tmpDate</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>"\t"</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>rand</span><span>.</span><span>nextInt</span><span>(</span><span>999</span><span>));</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>"\t"</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>Encrypt</span><span>.</span><span>md5</span><span>(</span><span>System</span><span>.</span><span>currentTimeMillis</span><span>()</span> <span>+</span> <span>""</span> <span>+</span> <span>rand</span><span>.</span><span>nextInt</span><span>(</span><span>99999999</span><span>)));</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>"\t"</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>rand</span><span>.</span><span>nextInt</span><span>(</span><span>999</span><span>)</span> <span>%</span> <span>2</span> <span>==</span> <span>0</span> <span>?</span> <span>"AA."</span> <span>:</span> <span>"BB"</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>"\t"</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>rand</span><span>.</span><span>nextFloat</span><span>()</span> <span>*</span> <span>2000</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>"\t"</span><span>);</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>rand</span><span>.</span><span>nextInt</span><span>(</span><span>9</span><span>));</span> </span><span> <span>builder</span><span>.</span><span>append</span><span>(</span><span>"\n"</span><span>);</span> </span><span> <span>}</span> </span><span> <span>System</span><span>.</span><span>out</span><span>.</span><span>println</span><span>(</span><span>"write data:"</span> <span>+</span> <span>i</span><span>);</span> </span><span> <span>outStream</span><span>.</span><span>write</span><span>(</span><span>builder</span><span>.</span><span>toString</span><span>().</span><span>getBytes</span><span>(</span><span>CHARCODE</span><span>));</span> </span><span> <span>outStream</span><span>.</span><span>close</span><span>();</span> </span><span><span>}</span> <span>catch</span> <span>(</span><span>Exception</span> <span>e</span><span>)</span> <span>{</span> </span><span> <span>e</span><span>.</span><span>printStackTrace</span><span>();</span> </span><span><span>}</span> </span><span><span>System</span><span>.</span><span>out</span><span>.</span><span>println</span><span>(</span><span>System</span><span>.</span><span>currentTimeMillis</span><span>()</span> <span>/</span> <span>1000</span> <span>-</span> <span>start</span><span>);</span> </span></span></code> |
这段代码会生成一个数据文件,每一行为一条记录,然后再使用上面提到的 LOAD DATA 来导入数据就可以了,我在公司的电脑下(2G内存+垃圾双核CPU,MySQL直接装在windows下,没任何优化,developer模式)每秒能达到近万条的插入速度,比其他方式都快很多。
另外如果想直接用GUI工具操作也可以,比如SQLYog中,右键要导入的表,选择Import – Import CSV Data Using Load Local.. 然后设置好编码、分隔符后就可以直接导入了。

本篇文章给大家带来了关于mysql的相关知识,其中主要介绍了关于架构原理的相关内容,MySQL Server架构自顶向下大致可以分网络连接层、服务层、存储引擎层和系统文件层,下面一起来看一下,希望对大家有帮助。

mysql的msi与zip版本的区别:1、zip包含的安装程序是一种主动安装,而msi包含的是被installer所用的安装文件以提交请求的方式安装;2、zip是一种数据压缩和文档存储的文件格式,msi是微软格式的安装包。

方法:1、利用right函数,语法为“update 表名 set 指定字段 = right(指定字段, length(指定字段)-1)...”;2、利用substring函数,语法为“select substring(指定字段,2)..”。

在mysql中,可以利用char()和REPLACE()函数来替换换行符;REPLACE()函数可以用新字符串替换列中的换行符,而换行符可使用“char(13)”来表示,语法为“replace(字段名,char(13),'新字符串') ”。

转换方法:1、利用cast函数,语法“select * from 表名 order by cast(字段名 as SIGNED)”;2、利用“select * from 表名 order by CONVERT(字段名,SIGNED)”语句。

本篇文章给大家带来了关于mysql的相关知识,其中主要介绍了关于MySQL复制技术的相关问题,包括了异步复制、半同步复制等等内容,下面一起来看一下,希望对大家有帮助。

在mysql中,可以利用REGEXP运算符判断数据是否是数字类型,语法为“String REGEXP '[^0-9.]'”;该运算符是正则表达式的缩写,若数据字符中含有数字时,返回的结果是true,反之返回的结果是false。

在mysql中,可利用“ALTER TABLE 表名 DROP INDEX unique key名”语句来删除unique key;ALTER TABLE语句用于对数据进行添加、删除或修改操作,DROP INDEX语句用于表示删除约束操作。


热AI工具

Undresser.AI Undress
人工智能驱动的应用程序,用于创建逼真的裸体照片

AI Clothes Remover
用于从照片中去除衣服的在线人工智能工具。

Undress AI Tool
免费脱衣服图片

Clothoff.io
AI脱衣机

AI Hentai Generator
免费生成ai无尽的。

热门文章

热工具

SublimeText3汉化版
中文版,非常好用

MinGW - 适用于 Windows 的极简 GNU
这个项目正在迁移到osdn.net/projects/mingw的过程中,你可以继续在那里关注我们。MinGW:GNU编译器集合(GCC)的本地Windows移植版本,可自由分发的导入库和用于构建本地Windows应用程序的头文件;包括对MSVC运行时的扩展,以支持C99功能。MinGW的所有软件都可以在64位Windows平台上运行。

适用于 Eclipse 的 SAP NetWeaver 服务器适配器
将Eclipse与SAP NetWeaver应用服务器集成。

记事本++7.3.1
好用且免费的代码编辑器

mPDF
mPDF是一个PHP库,可以从UTF-8编码的HTML生成PDF文件。原作者Ian Back编写mPDF以从他的网站上“即时”输出PDF文件,并处理不同的语言。与原始脚本如HTML2FPDF相比,它的速度较慢,并且在使用Unicode字体时生成的文件较大,但支持CSS样式等,并进行了大量增强。支持几乎所有语言,包括RTL(阿拉伯语和希伯来语)和CJK(中日韩)。支持嵌套的块级元素(如P、DIV),