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<a class="post-title-link" href="/2019/01/02/MySQL-RAND-函数/" itemprop="url">MySQL RAND()函数</a></h1>
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<p>最近在<a href="https://dzone.com" target="_blank" rel="noopener">Dzone</a>看到一篇关于MySQL不确定性函数的文章<a href="https://dzone.com/articles/nondeterministic-functions-in-mysql-ie-rand-can-su?edition=433193&utm_source=Zone%20Newsletter&utm_medium=email&utm_campaign=database%202018-12-28" target="_blank" rel="noopener">Nondeterministic Functions in MySQL (i.e. rand) Can Surprise You</a>，非常有意思</p>
<h3 id="MySQL问题复现"><a href="#MySQL问题复现" class="headerlink" title="MySQL问题复现"></a>MySQL问题复现</h3><h4 id="测试表结构："><a href="#测试表结构：" class="headerlink" title="测试表结构："></a>测试表结构：</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">CREATE TABLE `icp` (</span><br><span class="line"> `id` int(11) DEFAULT NULL,</span><br><span class="line"> `age` int(11) DEFAULT NULL,</span><br><span class="line"> `name` varchar(30) DEFAULT NULL,</span><br><span class="line"> `memo` varchar(600) DEFAULT NULL,</span><br><span class="line"> KEY `aind` (`age`,`name`,`memo`)</span><br><span class="line">) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4</span><br></pre></td></tr></table></figure>
<h4 id="构造测试数据："><a href="#构造测试数据：" class="headerlink" title="构造测试数据："></a>构造测试数据：</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br></pre></td><td class="code"><pre><span class="line">for i in $(seq 1 100000)</span><br><span class="line"> do</span><br><span class="line"> ┆ b="a$i"</span><br><span class="line"> c=''</span><br><span class="line"> ┆ d=$b</span><br><span class="line"> ┆ for f in $(seq 1 100)</span><br><span class="line"> ┆ ┆ do</span><br><span class="line"> ┆ ┆ ┆ c="$c$b"</span><br><span class="line"> ┆ ┆ done</span><br><span class="line"> ┆ mysql -uroot -padmin -S /tmp/mysql3341.sock dba -e "insert into icp values($i,1,'a$i','$c')"</span><br><span class="line">done</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">mysql> select * from icp limit 5;</span><br><span class="line">+------+------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+</span><br><span class="line">| id | age | name | memo |</span><br><span class="line">+------+------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+</span><br><span class="line">| 1 | 1 | a1 | a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1 |</span><br><span class="line">| 2 | 1 | a2 | a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2 |</span><br><span class="line">| 3 | 1 | a3 | a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3 |</span><br><span class="line">| 4 | 1 | a4 | a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4 |</span><br><span class="line">| 5 | 1 | a5 | a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5 |</span><br><span class="line">+------+------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+</span><br></pre></td></tr></table></figure>
<h4 id="查询语句："><a href="#查询语句：" class="headerlink" title="查询语句："></a>查询语句：</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">mysql> select * from icp where id=round(rand()*100000, 0);</span><br><span class="line">+-------+------+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+</span><br><span class="line">| id | age | name | memo |</span><br><span class="line">+-------+------+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+</span><br><span class="line">| 64957 | 1 | a64957 | a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957a64957 |</span><br><span class="line">| 97154 | 1 | a97154 | a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154a97154 |</span><br><span class="line">+-------+------+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+</span><br></pre></td></tr></table></figure>
<h4 id="RAND-函数"><a href="#RAND-函数" class="headerlink" title="RAND()函数"></a>RAND()函数</h4><p>可以看到使用主键<code>id=round(rand(),0)</code>的查询返回了多条结果，表示很不解。一直以为<code>where</code>条件后的<code>rand()</code>函数在查询中是一个确定的随机数，应该返回一行数据或0行数据。<br>查找官方文档，官方文档对<code>rand()</code>函数的说明：</p>
<p>RAND() in a WHERE clause is evaluated for every row (when selecting from one table) or combination of rows (when selecting from a multiple-table join). Thus, for optimizer purposes, RAND() is not a constant value and cannot be used for index optimizations.</p>
<p>即<code>where</code>条件中的<code>rand()</code>函数，与每一行数据进行比较时都会进行重新计算，因此上述查询返回2行数据也是符合预期的。表的数据量足够大，就可能会出现返回多行数据的情况。</p>
<p>在参考文中，也解释了查询的执行过程：</p>
<ol>
<li>首先读取第一行数据，获得id的值，计算<code>RAND()</code>的值，进行比较</li>
<li>剩下的数据，重复上述过程</li>
</ol>
<h4 id="RAND-N"><a href="#RAND-N" class="headerlink" title="RAND([N])"></a>RAND([N])</h4><p>如果指定整数N, 则它会被用作随机数的种子：</p>
<ul>
<li>如果为常量，则随机数种子在语句执行之前进行一次初始化</li>
<li>如果是列的情况，则针对列的每个值在调用时对种子进行初始化</li>
</ul>
<p>针对相同的种子N，<code>RAND(N)</code>每次都返回相同的值:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br></pre></td><td class="code"><pre><span class="line"> CREATE TABLE `t` (</span><br><span class="line"> `ts1` timestamp NULL DEFAULT NULL,</span><br><span class="line"> `ts2` timestamp NULL DEFAULT '0000-00-00 00:00:00',</span><br><span class="line"> `ts3` timestamp NULL DEFAULT CURRENT_TIMESTAMP,</span><br><span class="line"> `id` int(10) unsigned NOT NULL AUTO_INCREMENT,</span><br><span class="line"> PRIMARY KEY (`id`)</span><br><span class="line">) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">mysql> select id, rand() from t;</span><br><span class="line">+----+--------------------+</span><br><span class="line">| id | rand() |</span><br><span class="line">+----+--------------------+</span><br><span class="line">| 1 | 0.4543282598763036 |</span><br><span class="line">| 2 | 0.5590543677649036 |</span><br><span class="line">| 3 | 0.432287089929252 |</span><br><span class="line">+----+--------------------+</span><br><span class="line">3 rows in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select id, rand(3) from t;</span><br><span class="line">+----+---------------------+</span><br><span class="line">| id | rand(3) |</span><br><span class="line">+----+---------------------+</span><br><span class="line">| 1 | 0.9057697559760601 |</span><br><span class="line">| 2 | 0.37307905813034536 |</span><br><span class="line">| 3 | 0.14808605345719125 |</span><br><span class="line">+----+---------------------+</span><br><span class="line">3 rows in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select id, rand() from t;</span><br><span class="line">+----+---------------------+</span><br><span class="line">| id | rand() |</span><br><span class="line">+----+---------------------+</span><br><span class="line">| 1 | 0.4842723770851943 |</span><br><span class="line">| 2 | 0.12450064637186066 |</span><br><span class="line">| 3 | 0.16968613133736526 |</span><br><span class="line">+----+---------------------+</span><br><span class="line">3 rows in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select id, rand(3) from t;</span><br><span class="line">+----+---------------------+</span><br><span class="line">| id | rand(3) |</span><br><span class="line">+----+---------------------+</span><br><span class="line">| 1 | 0.9057697559760601 |</span><br><span class="line">| 2 | 0.37307905813034536 |</span><br><span class="line">| 3 | 0.14808605345719125 |</span><br><span class="line">+----+---------------------+</span><br><span class="line">3 rows in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select rand(id) from t;</span><br><span class="line">+---------------------+</span><br><span class="line">| rand(id) |</span><br><span class="line">+---------------------+</span><br><span class="line">| 0.40540353712197724 |</span><br><span class="line">| 0.6555866465490187 |</span><br><span class="line">| 0.9057697559760601 |</span><br><span class="line">+---------------------+</span><br><span class="line">3 rows in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select id,rand(id) from t;</span><br><span class="line">+----+---------------------+</span><br><span class="line">| id | rand(id) |</span><br><span class="line">+----+---------------------+</span><br><span class="line">| 1 | 0.40540353712197724 |</span><br><span class="line">| 2 | 0.6555866465490187 |</span><br><span class="line">| 3 | 0.9057697559760601 |</span><br><span class="line">+----+---------------------+</span><br><span class="line">3 rows in set (0.00 sec)</span><br></pre></td></tr></table></figure></p>
<h3 id="其他开源数据库随机函数"><a href="#其他开源数据库随机函数" class="headerlink" title="其他开源数据库随机函数"></a>其他开源数据库随机函数</h3><p>本文没有测试，参考文末参考文章，PostgreSQL与MySQL表现的一致，而SQLite不同，它是在语句行前进行计算。</p>
<h4 id="参考："><a href="#参考：" class="headerlink" title="参考："></a>参考：</h4><p><a href="https://dzone.com/articles/nondeterministic-functions-in-mysql-ie-rand-can-su?edition=433193&utm_source=Zone%20Newsletter&utm_medium=email&utm_campaign=database%202018-12-28" target="_blank" rel="noopener">Nondeterministic Functions in MySQL (i.e. rand) Can Surprise You</a></p>
<p><a href="https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_rand" target="_blank" rel="noopener">https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_rand</a></p>
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<h3 id="Maxwell"><a href="#Maxwell" class="headerlink" title="Maxwell"></a>Maxwell</h3><h4 id="Install"><a href="#Install" class="headerlink" title="Install"></a>Install</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">wget https://github.com/zendesk/maxwell/releases/download/v1.19.1/maxwell-1.19.1.tar.gz</span><br><span class="line"></span><br><span class="line">tar -xzf maxwell-1.19.1.tar.gz -C ../</span><br><span class="line"></span><br><span class="line">ln -s maxwell-1.19.1 maxwell</span><br></pre></td></tr></table></figure>
<h4 id="config"><a href="#config" class="headerlink" title="config"></a>config</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">cd maxwell</span><br><span class="line"></span><br><span class="line">cp config.properties.example config.properties</span><br></pre></td></tr></table></figure>
<p>config.properties填写必要信息<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">host=127.0.0.1</span><br><span class="line">user=</span><br><span class="line">password=</span><br><span class="line">port=</span><br><span class="line">schema_database=maxwell </span><br><span class="line">gtid_mode=true</span><br></pre></td></tr></table></figure></p>
<h3 id="kafka准备"><a href="#kafka准备" class="headerlink" title="kafka准备"></a>kafka准备</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic maxwell</span><br><span class="line"></span><br><span class="line">kafka-topics.sh --list --zookeeper localhost:2181</span><br></pre></td></tr></table></figure>
<h3 id="查看输出"><a href="#查看输出" class="headerlink" title="查看输出"></a>查看输出</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line">maxwell --user='' --password='' --host='127.0.0.1' --port=3306 --producer=stdout</span><br><span class="line"># 输出</span><br><span class="line">Using kafka version: 1.0.0</span><br><span class="line">15:35:42,837 WARN MaxwellMetrics - Metrics will not be exposed: metricsReportingType not configured.</span><br><span class="line">15:35:43,087 INFO SchemaStoreSchema - Creating maxwell database</span><br><span class="line">15:35:43,320 INFO Maxwell - Maxwell v1.19.1 is booting (StdoutProducer), starting at Position[BinlogPosition[mysql-bin.000003:7586], lastHeartbeat=0]</span><br><span class="line">15:35:43,449 INFO AbstractSchemaStore - Maxwell is capturing initial schema</span><br><span class="line">15:35:43,657 INFO BinlogConnectorReplicator - Setting initial binlog pos to: mysql-bin.000003:7586</span><br><span class="line">15:35:43,751 INFO BinaryLogClient - Connected to 127.0.0.1:3306 at mysql-bin.000003/7586 (sid:6379, cid:59)</span><br><span class="line">15:35:43,751 INFO BinlogConnectorLifecycleListener - Binlog connected.</span><br></pre></td></tr></table></figure>
<h4 id="mysql-ddl"><a href="#mysql-ddl" class="headerlink" title="mysql ddl"></a>mysql ddl</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br></pre></td><td class="code"><pre><span class="line">mysql> show create table t\G</span><br><span class="line">*************************** 1. row ***************************</span><br><span class="line"> Table: t</span><br><span class="line">Create Table: CREATE TABLE `t` (</span><br><span class="line"> `id` int(11) DEFAULT NULL</span><br><span class="line"> ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4</span><br><span class="line"></span><br><span class="line">mysql> alter table t add name varchar(20) not null default '';</span><br><span class="line"></span><br><span class="line">mysql> update t set name='mag';</span><br><span class="line">Query OK, 8 rows affected (0.01 sec)</span><br><span class="line">Rows matched: 8 Changed: 8 Warnings: 0</span><br><span class="line"></span><br><span class="line">mysql> insert t value(1000, 'test');</span><br><span class="line">Query OK, 1 row affected (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> delete from t where id=1000;</span><br><span class="line">Query OK, 1 row affected (0.01 sec)</span><br><span class="line"></span><br><span class="line">mysql> alter table t add index idx_name(name);</span><br><span class="line">Query OK, 0 rows affected (0.02 sec)</span><br><span class="line">Records: 0 Duplicates: 0 Warnings: 0</span><br></pre></td></tr></table></figure>
<p>输出<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line">15:50:24,323 INFO AbstractSchemaStore - storing schema @Position[BinlogPosition[mysql-bin.000003:89989], lastHeartbeat=1542268217331] after applying "alter table t add name varchar(20) not null default ''" to dba, new schema id is 2</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"xoffset":0,"data":{"id":1,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"xoffset":1,"data":{"id":2,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"xoffset":2,"data":{"id":2,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"xoffset":3,"data":{"id":34,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"xoffset":4,"data":{"id":35,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"xoffset":5,"data":{"id":100,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"xoffset":6,"data":{"id":101,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"update","ts":1542268253,"xid":950,"commit":true,"data":{"id":200,"name":"mag"},"old":{"name":""}}</span><br><span class="line">{"database":"dba","table":"t","type":"insert","ts":1542268284,"xid":962,"commit":true,"data":{"id":1000,"name":"test"}}</span><br><span class="line">{"database":"dba","table":"t","type":"delete","ts":1542268294,"xid":968,"commit":true,"data":{"id":1000,"name":"test"}}</span><br><span class="line">15:52:59,775 INFO AbstractSchemaStore - storing schema @Position[BinlogPosition[mysql-bin.000003:105597], lastHeartbeat=1542268378572] after applying "alter table t add index idx_name(name)" to dba, new schema id is 3</span><br></pre></td></tr></table></figure></p>
<h4 id="用配置文件启动，数据写入kafka"><a href="#用配置文件启动，数据写入kafka" class="headerlink" title="用配置文件启动，数据写入kafka"></a>用配置文件启动，数据写入kafka</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br></pre></td><td class="code"><pre><span class="line">[root@canal maxwell]# maxwell --config config.properties --daemon</span><br><span class="line">[root@canal maxwell]# maxwell --config config.properties</span><br><span class="line">Using kafka version: 1.0.0</span><br><span class="line">15:55:34,751 WARN MaxwellMetrics - Metrics will not be exposed: metricsReportingType not configured.</span><br><span class="line">15:55:35,070 INFO SchemaStoreSchema - Creating dba database</span><br><span class="line">15:55:35,361 INFO ProducerConfig - ProducerConfig values:</span><br><span class="line"> acks = 1</span><br><span class="line"> batch.size = 16384</span><br><span class="line"> bootstrap.servers = [localhost:9092]</span><br><span class="line"> buffer.memory = 33554432</span><br><span class="line"> client.id =</span><br><span class="line"> compression.type = snappy</span><br><span class="line"> connections.max.idle.ms = 540000</span><br><span class="line"> enable.idempotence = false</span><br><span class="line"> interceptor.classes = null</span><br><span class="line"> key.serializer = class org.apache.kafka.common.serialization.StringSerializer</span><br><span class="line"> linger.ms = 0</span><br><span class="line"> max.block.ms = 60000</span><br><span class="line"> max.in.flight.requests.per.connection = 5</span><br><span class="line"> max.request.size = 1048576</span><br><span class="line"> metadata.max.age.ms = 300000</span><br><span class="line"> metric.reporters = []</span><br><span class="line"> metrics.num.samples = 2</span><br><span class="line"> metrics.recording.level = INFO</span><br><span class="line"> metrics.sample.window.ms = 30000</span><br><span class="line"> partitioner.class = class org.apache.kafka.clients.producer.internals.DefaultPartitioner</span><br><span class="line"> receive.buffer.bytes = 32768</span><br><span class="line"> reconnect.backoff.max.ms = 1000</span><br><span class="line"> reconnect.backoff.ms = 50</span><br><span class="line"> request.timeout.ms = 30000</span><br><span class="line"> retries = 0</span><br><span class="line"> retry.backoff.ms = 100</span><br><span class="line"> sasl.jaas.config = null</span><br><span class="line"> sasl.kerberos.kinit.cmd = /usr/bin/kinit</span><br><span class="line"> sasl.kerberos.min.time.before.relogin = 60000</span><br><span class="line"> sasl.kerberos.service.name = null</span><br><span class="line"> sasl.kerberos.ticket.renew.jitter = 0.05</span><br><span class="line"> sasl.kerberos.ticket.renew.window.factor = 0.8</span><br><span class="line"> sasl.mechanism = GSSAPI</span><br><span class="line"> security.protocol = PLAINTEXT</span><br><span class="line"> send.buffer.bytes = 131072</span><br><span class="line"> ssl.cipher.suites = null</span><br><span class="line"> ssl.enabled.protocols = [TLSv1.2, TLSv1.1, TLSv1]</span><br><span class="line"> ssl.endpoint.identification.algorithm = null</span><br><span class="line"> ssl.key.password = null</span><br><span class="line"> ssl.keymanager.algorithm = SunX509</span><br><span class="line"> ssl.keystore.location = null</span><br><span class="line"> ssl.keystore.password = null</span><br><span class="line"> ssl.keystore.type = JKS</span><br><span class="line"> ssl.protocol = TLS</span><br><span class="line"> ssl.provider = null</span><br><span class="line"> ssl.secure.random.implementation = null</span><br><span class="line"> ssl.trustmanager.algorithm = PKIX</span><br><span class="line"> ssl.truststore.location = null</span><br><span class="line"> ssl.truststore.password = null</span><br><span class="line"> ssl.truststore.type = JKS</span><br><span class="line"> transaction.timeout.ms = 60000</span><br><span class="line"> transactional.id = null</span><br><span class="line"> value.serializer = class org.apache.kafka.common.serialization.StringSerializer</span><br><span class="line"></span><br><span class="line">15:55:35,412 INFO AppInfoParser - Kafka version : 1.0.0</span><br><span class="line">15:55:35,413 INFO AppInfoParser - Kafka commitId : aaa7af6d4a11b29d</span><br><span class="line">15:55:35,437 INFO Maxwell - Maxwell v1.19.1 is booting (MaxwellKafkaProducer), starting at Position[BinlogPosition[59ca6064-e0ea-11e8-9adc-00163e123442:1-289], lastHeartbeat=0]</span><br><span class="line">15:55:35,569 INFO AbstractSchemaStore - Maxwell is capturing initial schema</span><br><span class="line">15:55:35,741 INFO BinlogConnectorReplicator - Setting initial gtid to: 59ca6064-e0ea-11e8-9adc-00163e123442:1-289</span><br><span class="line">15:55:35,836 INFO BinaryLogClient - Connected to 127.0.0.1:3341 at 59ca6064-e0ea-11e8-9adc-00163e123442:1-289 (sid:6379, cid:66)</span><br><span class="line">15:55:35,836 INFO BinlogConnectorLifecycleListener - Binlog connected.</span><br></pre></td></tr></table></figure>
<h4 id="kafka消费数据"><a href="#kafka消费数据" class="headerlink" title="kafka消费数据"></a>kafka消费数据</h4><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"></span><br><span class="line">mysql> create table t1(id int);</span><br><span class="line">Query OK, 0 rows affected (0.02 sec)</span><br><span class="line"></span><br><span class="line">mysql> alter table t1 add name varchar(20);</span><br><span class="line">Query OK, 0 rows affected (0.03 sec)</span><br><span class="line">Records: 0 Duplicates: 0 Warnings: 0</span><br><span class="line"></span><br><span class="line">[root@canal maxwell]# kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --from-beginning --topic maxwell</span><br><span class="line"></span><br><span class="line">{"type":"table-create","database":"dba","table":"t1","def":{"database":"dba","charset":"utf8mb4","table":"t1","columns":[{"type":"int","name":"id","signed":true}],"primary-key":[]},"ts":1542353432000,"sql":"create table t1(id int)"}</span><br><span class="line">{"type":"table-alter","database":"dba","table":"t1","old":{"database":"dba","charset":"utf8mb4","table":"t1","columns":[{"type":"int","name":"id","signed":true}],"primary-key":[]},"def":{"database":"dba","charset":"utf8mb4","table":"t1","columns":[{"type":"int","name":"id","signed":true},{"type":"varchar","name":"name","charset":"utf8mb4"}],"primary-key":[]},"ts":1542353617000,"sql":"alter table t1 add name varchar(20)"}</span><br></pre></td></tr></table></figure>
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<h3 id="TIMESTAMP和DATETIME列自动填充及更新"><a href="#TIMESTAMP和DATETIME列自动填充及更新" class="headerlink" title="TIMESTAMP和DATETIME列自动填充及更新"></a>TIMESTAMP和DATETIME列自动填充及更新</h3><p>TIMESTAMP和DATETIME列可以用当前的日期和时间进行自动填充或更新。表中的timestamp或datetime列，可以使用当前时间作为默认值或自动更新的值:</p>
<ul>
<li>数据写入时，不用给自动填充列写入值，其会使用当前时间作为值写入</li>
<li>当行中其他列的值更新时，随更新而更新的时间列，会自动更新到当前时间。当其它列的值没有发生变化时（即使直行更新语句，但值没变），随更新而更新的时间列不进行更新。如果其它列更新，不希望随更新而更新时间列变化，可以明确将其更新为原来的值。随更新而更新的同样可以直接更新其值。<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line">mysql> select * from t2;</span><br><span class="line">+---------------------+------+</span><br><span class="line">| ts1 | id |</span><br><span class="line">+---------------------+------+</span><br><span class="line">| 2018-11-04 15:54:59 | 1 |</span><br><span class="line">| 2018-11-04 15:54:39 | 1 |</span><br><span class="line">+---------------------+------+</span><br><span class="line">2 rows in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> update t2 set id=1;</span><br><span class="line">Query OK, 0 rows affected (0.00 sec)</span><br><span class="line">Rows matched: 2 Changed: 0 Warnings: 0</span><br><span class="line"></span><br><span class="line">mysql> select * from t2;</span><br><span class="line">+---------------------+------+</span><br><span class="line">| ts1 | id |</span><br><span class="line">+---------------------+------+</span><br><span class="line">| 2018-11-04 15:54:59 | 1 |</span><br><span class="line">| 2018-11-04 15:54:39 | 1 |</span><br><span class="line">+---------------------+------+</span><br><span class="line">2 rows in set (0.01 sec)</span><br><span class="line"></span><br><span class="line">mysql> update t2 set id = 2, ts1=ts1; ## 时间列保持不变</span><br><span class="line">Query OK, 2 rows affected (0.00 sec)</span><br><span class="line">Rows matched: 2 Changed: 2 Warnings: 0</span><br><span class="line"></span><br><span class="line">mysql> select * from t2;</span><br><span class="line">+---------------------+------+</span><br><span class="line">| ts1 | id |</span><br><span class="line">+---------------------+------+</span><br><span class="line">| 2018-11-04 15:54:59 | 2 |</span><br><span class="line">| 2018-11-04 15:54:39 | 2 |</span><br><span class="line">+---------------------+------+</span><br><span class="line">2 rows in set (0.00 sec)</span><br></pre></td></tr></table></figure>
</li>
</ul>
<p>当前时间戳:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">select current_timestamp(), now(), localtime, localtime(), localtimestamp, localtimestamp();</span><br><span class="line">+---------------------+---------------------+---------------------+---------------------+---------------------+---------------------+</span><br><span class="line">| current_timestamp() | now() | localtime | localtime() | localtimestamp | localtimestamp() |</span><br><span class="line">+---------------------+---------------------+---------------------+---------------------+---------------------+---------------------+</span><br><span class="line">| 2018-11-04 18:42:43 | 2018-11-04 18:42:43 | 2018-11-04 18:42:43 | 2018-11-04 18:42:43 | 2018-11-04 18:42:43 | 2018-11-04 18:42:43 |</span><br><span class="line">+---------------------+---------------------+---------------------+---------------------+---------------------+---------------------+</span><br></pre></td></tr></table></figure></p>
<h3 id="explicit-defaults-for-timestamp参数"><a href="#explicit-defaults-for-timestamp参数" class="headerlink" title="explicit_defaults_for_timestamp参数"></a>explicit_defaults_for_timestamp参数</h3><p>从8.0.2起，默认开启，之前默认关闭。当前状态为deprecated。其决定着服务器是否为timestamp列中的默认值和NULL值处理启用某些非标准行为。参数启用后，则禁用这些非标准行为。</p>
<h4 id="explicit-defaults-for-timestamp-0"><a href="#explicit-defaults-for-timestamp-0" class="headerlink" title="explicit_defaults_for_timestamp=0"></a>explicit_defaults_for_timestamp=0</h4><p>explicit_defaults_for_timestamp关闭时，timestamp列有以下一些非标准行为:</p>
<ul>
<li><p>TIMESTAMP 没有明确声明null属性的列被自动声明为not null。当给列null值时，列更新为当前的时间戳。</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line">create table t4(ts1 timestamp default '2018');</span><br><span class="line"></span><br><span class="line">mysql> show create table t4\G</span><br><span class="line">*************************** 1. row ***************************</span><br><span class="line"> Table: t4</span><br><span class="line">Create Table: CREATE TABLE `t4` (</span><br><span class="line"> `ts1` timestamp NOT NULL DEFAULT '2018-01-01 00:00:00'</span><br><span class="line">) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4</span><br><span class="line">1 row in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> insert t4 values(null);</span><br><span class="line">Query OK, 1 row affected (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select * from t4;</span><br><span class="line">+---------------------+</span><br><span class="line">| ts1 |</span><br><span class="line">+---------------------+</span><br><span class="line">| 2018-11-04 17:36:55 |</span><br><span class="line">+---------------------+</span><br><span class="line">1 row in set (0.00 sec)</span><br></pre></td></tr></table></figure>
</li>
<li><p>表中的第一个TIMESTAMP列，如果没有明确声明null属性，或明确声明default, 或明确声明on update。则自动声明为 DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP。</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br></pre></td><td class="code"><pre><span class="line">mysql> create table t5(ts1 timestamp,ts2 timestamp);</span><br><span class="line">Query OK, 0 rows affected (0.02 sec)</span><br><span class="line"></span><br><span class="line">mysql> show create table t5\G</span><br><span class="line">*************************** 1. row ***************************</span><br><span class="line"> Table: t5</span><br><span class="line">Create Table: CREATE TABLE `t5` (</span><br><span class="line"> `ts1` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,</span><br><span class="line"> `ts2` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00'</span><br><span class="line">) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4</span><br><span class="line">1 row in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> insert t5(ts2) value(null);</span><br><span class="line">Query OK, 1 row affected (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select * from t5;</span><br><span class="line">+---------------------+---------------------+</span><br><span class="line">| ts1 | ts2 |</span><br><span class="line">+---------------------+---------------------+</span><br><span class="line">| 2018-11-04 17:44:11 | 2018-11-04 17:44:11 |</span><br><span class="line">+---------------------+---------------------+</span><br><span class="line">1 row in set (0.00 sec)</span><br></pre></td></tr></table></figure>
</li>
<li><p>上例中的第二个时间列，如果没有其它声明，则声明为not null default ‘0000-00-00 00:00:00’(the ‘zero’ timestamp), 插入数据时，不指定该列时，其填充’0000-00-00 00:00:00’，并且没有警告</p>
</li>
</ul>
<p>默认值同样会受SQL mode的影响。在严格模式及NO_ZERO_DATE模式下，’0000-00-00 00:00:00’是无效的。</p>
<p>这些非标准的行为，目前处于deprecated状态，在未来的版本中，会被移除。</p>
<h4 id="explicit-defaults-for-timestamp-1"><a href="#explicit-defaults-for-timestamp-1" class="headerlink" title="explicit_defaults_for_timestamp=1"></a>explicit_defaults_for_timestamp=1</h4><p>explicit_defaults_for_timestamp=1将禁用timestamp列默认值及null值处理的非标准行为:</p>
<ul>
<li>使用null值无法将timestamp列更新为当前时间戳。要使timestamp列为当前时间戳，可以使用current_timestamp()或now().</li>
<li>TIMESTAMP 没有明确声明null属性的列则默认null属性，并且允许null值。使用null给列赋值，则得到null.</li>
<li>TIMESTAMP 明确声明not null属性的则不允许null值。如果为该列插入null值，在单行插入或严格模式启用时会导致错误，在非严格模式下多行插入时，插入’0000-00-00 00:00:00’。在任何情况下, 都不能通过给列赋值null, 来使其为当前时间戳。</li>
<li>TIMESTAMP 明确声明not null且没有声明default的列则被认为是该列没有默认值。在插入数据时，如果没有给该列赋值，结果取决于SQL mode。严格模式，直接报错。非严格模式，该列被声明为有隐式默认值’0000-00-00 00:00:00’，并产生warnig。这与MySQL处理其它诸如DATETIME的时间类型的方式相似。</li>
<li>TIMESTAMP列不会被自动声明DEFAULT CURRENT_TIMESTAMP or ON UPDATE CURRENT_TIMESTAMP。这些属性必须明确声明指定。</li>
<li>第一个TIMESTAMP列和其它的TIMESTAMP列的处理方式没有不同。</li>
</ul>
<p>explicit_defaults_for_timestamp=0启动服务时，在error log中有:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">[Warning] TIMESTAMP with implicit DEFAULT value is deprecated.</span><br><span class="line">Please use --explicit_defaults_for_timestamp server option (see</span><br><span class="line">documentation for more details).</span><br></pre></td></tr></table></figure></p>
<p>示例:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br></pre></td><td class="code"><pre><span class="line">mysql> set explicit_defaults_for_timestamp=1;</span><br><span class="line">Query OK, 0 rows affected (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> insert t5(ts2) value(null);</span><br><span class="line">ERROR 1048 (23000): Column 'ts2' cannot be null</span><br><span class="line">mysql> insert t5(ts2) value(null),(null),(null);</span><br><span class="line">ERROR 1048 (23000): Column 'ts2' cannot be null</span><br><span class="line">mysql> insert t5(ts2) values(null),(null),(null);</span><br><span class="line">ERROR 1048 (23000): Column 'ts2' cannot be null</span><br><span class="line">mysql> select @sql_mode;</span><br><span class="line">+-----------+</span><br><span class="line">| @sql_mode |</span><br><span class="line">+-----------+</span><br><span class="line">| NULL |</span><br><span class="line">+-----------+</span><br><span class="line">1 row in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> select @@sql_mode;</span><br><span class="line">+-------------------------------------------------------------------------------------------+</span><br><span class="line">| @@sql_mode |</span><br><span class="line">+-------------------------------------------------------------------------------------------+</span><br><span class="line">| STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |</span><br><span class="line">+-------------------------------------------------------------------------------------------+</span><br><span class="line">1 row in set (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> set @@sql_mode=NO_ENGINE_SUBSTITUTION;</span><br><span class="line">Query OK, 0 rows affected, 1 warning (0.00 sec)</span><br><span class="line"></span><br><span class="line">mysql> insert t5(ts2) values(null),(null),(null);</span><br><span class="line">Query OK, 3 rows affected, 1 warning (0.00 sec)</span><br><span class="line">Records: 3 Duplicates: 0 Warnings: 1</span><br><span class="line"></span><br><span class="line">mysql> select * from t5;</span><br><span class="line">+---------------------+---------------------+</span><br><span class="line">| ts1 | ts2 |</span><br><span class="line">+---------------------+---------------------+</span><br><span class="line">| 2018-11-04 17:44:11 | 2018-11-04 17:44:11 |</span><br><span class="line">| 2018-11-04 18:16:49 | 2018-11-04 18:16:49 |</span><br><span class="line">| 2018-11-04 18:18:32 | 0000-00-00 00:00:00 |</span><br><span class="line">| 2018-11-04 18:18:32 | 0000-00-00 00:00:00 |</span><br><span class="line">| 2018-11-04 18:18:32 | 0000-00-00 00:00:00 |</span><br><span class="line">+---------------------+---------------------+</span><br><span class="line">5 rows in set (0.00 sec)</span><br></pre></td></tr></table></figure></p>
<h3 id="参考"><a href="#参考" class="headerlink" title="参考"></a>参考</h3><p><a href="https://dev.mysql.com/doc/refman/8.0/en/timestamp-initialization.html" target="_blank" rel="noopener">https://dev.mysql.com/doc/refman/8.0/en/timestamp-initialization.html</a></p>
<p><a href="https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_explicit_defaults_for_timestamp" target="_blank" rel="noopener">https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_explicit_defaults_for_timestamp</a></p>
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<h1 id="1-安装"><a href="#1-安装" class="headerlink" title="1 安装"></a>1 安装</h1><p>下载<a href="https://github.com/sysown/proxysql/releases" target="_blank" rel="noopener">ProxySQL</a>的安装包，这里下载当下最新版本proxysql-1.4.9-1-centos7.x86_64.rpm。<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">yum localinstall proxysql-1.4.9-1-centos7.x86_64.rpm -y</span><br></pre></td></tr></table></figure></p>
<p>proxysql配置文件<code>/etc/proxysql.cnf</code>，只在第一次启动的时候加载初始化，后续启动数据从proxysql.db加载。默认数据目录是<code>/var/lib/proxysql</code>，在这里我们修改为<code>/data/proxysql</code>：<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br></pre></td><td class="code"><pre><span class="line">#file proxysql.cfg</span><br><span class="line"></span><br><span class="line"># This config file is parsed using libconfig , and its grammar is described in:</span><br><span class="line"># http://www.hyperrealm.com/libconfig/libconfig_manual.html#Configuration-File-Grammar</span><br><span class="line"># Grammar is also copied at the end of this file</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"></span><br><span class="line">datadir="/data/proxysql"</span><br><span class="line"></span><br><span class="line">admin_variables=</span><br><span class="line">{</span><br><span class="line"> admin_credentials="admin:admin"</span><br><span class="line"># mysql_ifaces="127.0.0.1:6032;/tmp/proxysql_admin.sock"</span><br><span class="line"> mysql_ifaces="0.0.0.0:6032"</span><br><span class="line"># refresh_interval=2000</span><br><span class="line"># debug=true</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line">mysql_variables=</span><br><span class="line">{</span><br><span class="line"> threads=4</span><br><span class="line"> max_connections=2048</span><br><span class="line"> default_query_delay=0</span><br><span class="line"> default_query_timeout=36000000</span><br><span class="line"> have_compress=true</span><br><span class="line"> poll_timeout=2000</span><br><span class="line"># interfaces="0.0.0.0:6033;/tmp/proxysql.sock"</span><br><span class="line"> interfaces="0.0.0.0:6033"</span><br><span class="line"> default_schema="information_schema"</span><br><span class="line"> stacksize=1048576</span><br><span class="line"> server_version="5.7.21"</span><br><span class="line"> connect_timeout_server=3000</span><br><span class="line"># make sure to configure monitor username and password</span><br><span class="line"># https://github.com/sysown/proxysql/wiki/Global-variables#mysql-monitor_username-mysql-monitor_password</span><br><span class="line"> monitor_username="monitor"</span><br><span class="line"> monitor_password="monitor"</span><br><span class="line"> monitor_history=600000</span><br><span class="line"> monitor_connect_interval=60000</span><br><span class="line"> monitor_ping_interval=10000</span><br><span class="line"> monitor_read_only_interval=1500</span><br><span class="line"> monitor_read_only_timeout=500</span><br><span class="line"> ping_interval_server_msec=120000</span><br><span class="line"> ping_timeout_server=500</span><br><span class="line"> commands_stats=true</span><br><span class="line"> sessions_sort=true</span><br><span class="line"> connect_retries_on_failure=10</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"># defines all the MySQL servers</span><br><span class="line">mysql_servers =</span><br><span class="line">(</span><br><span class="line"> {</span><br><span class="line"> address = "127.0.0.1" # no default, required . If port is 0 , address is interpred as a Unix Socket Domain</span><br><span class="line"> port = 3341 # no default, required . If port is 0 , address is interpred as a Unix Socket Domain</span><br><span class="line"> hostgroup = 0 # no default, required</span><br><span class="line"> status = "ONLINE" # default: ONLINE</span><br><span class="line"> weight = 1 # default: 1</span><br><span class="line"> compression = 0 # default: 0</span><br><span class="line"># max_replication_lag = 10 # default 0 . If greater than 0 and replication lag passes such threshold, the server is shunned</span><br><span class="line"> }</span><br><span class="line"># {</span><br><span class="line"># address = "/var/lib/mysql/mysql.sock"</span><br><span class="line"># port = 0</span><br><span class="line"># hostgroup = 0</span><br><span class="line"># },</span><br><span class="line"># {</span><br><span class="line"># address="127.0.0.1"</span><br><span class="line"># port=21891</span><br><span class="line"># hostgroup=0</span><br><span class="line"># max_connections=200</span><br><span class="line"># },</span><br><span class="line"># { address="127.0.0.2" , port=3306 , hostgroup=0, max_connections=5 },</span><br><span class="line"># { address="127.0.0.1" , port=21892 , hostgroup=1 },</span><br><span class="line"># { address="127.0.0.1" , port=21893 , hostgroup=1 }</span><br><span class="line"># { address="127.0.0.2" , port=3306 , hostgroup=1 },</span><br><span class="line"># { address="127.0.0.3" , port=3306 , hostgroup=1 },</span><br><span class="line"># { address="127.0.0.4" , port=3306 , hostgroup=1 },</span><br><span class="line"># { address="/var/lib/mysql/mysql.sock" , port=0 , hostgroup=1 }</span><br><span class="line">)</span><br><span class="line"></span><br><span class="line"># arg5="/var/lib/proxysql/proxysql_galera_checker.log"</span><br><span class="line"># }</span><br><span class="line">)</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">mysql_replication_hostgroups=</span><br><span class="line">(</span><br><span class="line"># {</span><br><span class="line"># writer_hostgroup=30</span><br><span class="line"># reader_hostgroup=40</span><br><span class="line"># comment="test repl 1"</span><br><span class="line"># },</span><br><span class="line"># {</span><br><span class="line"># writer_hostgroup=50</span><br><span class="line"># reader_hostgroup=60</span><br><span class="line"># comment="test repl 2"</span><br><span class="line"># }</span><br><span class="line">)</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"></span><br><span class="line"></span><br><span class="line"># http://www.hyperrealm.com/libconfig/libconfig_manual.html#Configuration-File-Grammar</span><br><span class="line">#</span><br><span class="line"># Below is the BNF grammar for configuration files. Comments and include directives are not part of the grammar, so they are not included here.</span><br><span class="line">#</span><br><span class="line"># configuration = setting-list | empty</span><br><span class="line">#</span><br><span class="line"># setting-list = setting | setting-list setting</span><br><span class="line">#</span><br><span class="line"># setting = name (":" | "=") value (";" | "," | empty)</span><br><span class="line">#</span><br><span class="line"># value = scalar-value | array | list | group</span><br><span class="line">#</span><br><span class="line"># value-list = value | value-list "," value</span><br><span class="line">#</span><br><span class="line"># scalar-value = boolean | integer | integer64 | hex | hex64 | float</span><br><span class="line"># | string</span><br><span class="line">#</span><br><span class="line"># scalar-value-list = scalar-value | scalar-value-list "," scalar-value</span><br><span class="line">#</span><br><span class="line"># array = "[" (scalar-value-list | empty) "]"</span><br><span class="line">#</span><br><span class="line"># list = "(" (value-list | empty) ")"</span><br><span class="line">#</span><br><span class="line"># group = "{" (setting-list | empty) "}"</span><br><span class="line">#</span><br><span class="line"># empty =</span><br></pre></td></tr></table></figure></p>
<p>修改proxysql的systemctl服务，<code>vim /etc/init.d/proxysql</code>:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">...</span><br><span class="line">OLDDATADIR="/data/proxysql"</span><br><span class="line">DATADIR="/data/proxysql"</span><br><span class="line">OPTS="-c /etc/proxysql.cnf -D $DATADIR"</span><br><span class="line">PIDFILE="$DATADIR/proxysql.pid"</span><br><span class="line">...</span><br></pre></td></tr></table></figure></p>
<p>启动:<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">systemctl start proxysql</span><br></pre></td></tr></table></figure></p>
<p><img src="./images/01.jpg" alt="proxy配置层及命令"></p>
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