SQLSERVER中KeyHashValue的作用（下） 昨天中午跟高文佳童鞋讨论了 KeyHashValue 的作用，到最后还是没有讨论出结果 昨天晚上德国的兄弟傅文伟做了一下实验，将实验结果交给我 感谢他们 SQLSERVER中KeyHashValue的作用（上） 虽然对于keyhashvalue的研究还有
SQLSERVER中KeyHashValue的作用（下）
昨天中午跟高文佳童鞋讨论了KeyHashValue的作用，到最后还是没有讨论出结果
昨天晚上德国的兄弟傅文伟做了一下实验，将实验结果交给我
感谢他们
SQLSERVER中KeyHashValue的作用（上）
虽然对于keyhashvalue的研究还有很多问题还没有解决，但是基本可以确定“keyhashvalue是用来锁定资源的”
而不是我之前说的，在seek的时候根据这个KeyHashValue来快速查找到对应的记录
误导大家了，真的不好意思！！！！
资源 说明
RID 用于锁定堆（heap）中的某一行
KEY 用于锁定索引上的某一行，或者某个索引键
PAGE 锁定数据库中的一个8KB页，例如数据页或索引页
EXTENT 一组连续的8页（区）
HOBT 锁定整个堆或B树的锁
TABLE 锁定包括所有数据和索引的整个表
FILE 数据库文件
APPLICATION 应用程序专用的资源
METADATA 元数据锁
ALLOCATION_UNIT 分配单元
DATABASE 整个数据库
KEY是靠生成的这个KeyHashValue来进行锁定索引中的行
KEY 用于锁定索引上的某一行
为什么需要这个KeyHashValue？？？
由于很苟很苟没有写C#代码，不过我觉得从C#的多线程同步来理解会更加好
例如：
lock 语句 lock 确保当一个线程位于代码的临界区时，另一个线程不进入临界区。如果其他线程试图进入锁定的代
码，则它将一直等待（即被阻止），直到该对象被释放，大家可以把同步对象理解为KeyHashValue
c# 多线程同步
c# 多线程同步
大家还是看给出的文章链接吧，因为本人很苟很苟没有写C#代码了，细节的东西看文章比较好
网上有很多相关的文章：
例如
建立索引的时候为什麽有900bytes的限制
为了性能，不可能让您在比较大的数据类型下，而且存储了非常多的数据的字段上建立索引
因为这样做的话，要计算出KeyHashValue就会非常消耗性能
这篇文章：Improvement in minimizing lockhash key collisions in SQL Server 2008R2 and its impact on concurrency
Since the key to a row could be as large as 900 bytes, using the real key values would have inflicted larger memory consumption.
引入
The solution to this problem was found when designing SQL server 7.0 in 1996 and 1997 by using the key of the row and apply
a hash algorithm to it which then results in a 6 byte long lockhash value
我将这些文章整理到我的文章里：undocumented virtual column %%lockres%%
在SQLSERVER2005下跟SQLSERVER2012下，建立相同的聚集索引，你会看到在SQL2005下，表的聚集索引页面有KeyHashValue
但是在SQL2012下，表的聚集索引页面的KeyHashValue列全部为NULL
由于我没有SQL2008，所以没有测试SQL2008，估计从SQL2008开始，KeyHashValue开始有些变化了
在SQL2005里，你使用dbcc page查看数据页面，数据页面里的每行记录是没有显示KeyHashValue的，不知道要打开哪个跟踪标记才能看到
在SQL2005里唯一能看到数据页面中的keyhashvalue只有使用%%lockres%%
而在SQL2012，不用做任何设置，使用dbcc page就可以看到KeyHashValue
当然也可以用%%lockres%%：
<span>1</span> <span>SELECT</span> <span>%%</span>lockres<span>%%</span> <span>AS</span> <span>'</span><span>数据页的keyhashvalue</span><span>'</span> <span>FROM</span> 表名
页面126是数据页面
<span>1</span> <span>DBCC</span> TRACEON(<span>3604</span>,<span>-</span><span>1</span><span>) </span><span>2</span> <span>GO</span> <span>3</span> <span>DBCC</span> PAGE(testhashkey,<span>1</span>,<span>126</span>,<span>3</span><span>) </span><span>4</span> <span>GO</span>
Slot 0 Offset 0x0 Length 0 Length (physical) 0
KeyHashValue = (8194443284a0)
DBCC 执行完毕。如果 DBCC 输出了错误信息，请与系统管理员联系。
SQL2012最大的改进是提示非常清晰，而且以前的SQLSERVER版本没有显示出来的东西都给你显示出来了，
这样有时候就不用做那么多系统表的表连接，如果是以前版本的SQLSERVER要查看某一个信息的时候又要做
这个系统表的表连接又要做那个表的表连接才能得出这个自己想看的东西，非常繁琐
例如如下改进：
聚集索引页面的显示，SQL2005是没有Row Size这一列的
下面的所有测试都是基于SQLSERVER2005 SP4 个人开发版
聚集索引
创建聚集索引的时候无论是唯一还是不唯一都会产生KeyHashValue
但是为了实验的方便，我这里只创建唯一聚集索引，因为不唯一的话会产生range locks不方便查看结果
详细请参考文章：Range locks
脚本：
<span> 1</span> <span>USE</span><span> master </span><span> 2</span> <span>GO</span> <span> 3</span> <span>CREATE</span> <span>DATABASE</span><span> testhashkey </span><span> 4</span> <span>GO</span> <span> 5</span> <span> 6</span> <span>USE</span><span> testhashkey </span><span> 7</span> <span>GO</span> <span> 8</span> <span> 9</span> <span>--</span><span>------------------------------------------</span> <span>10</span> <span>--</span><span>测试聚集索引</span> <span>11</span> <span>CREATE</span> <span>TABLE</span><span> testcluster </span><span>12</span> <span> ( </span><span>13</span> a <span>NVARCHAR</span>(<span>3800</span>) <span>NOT</span> <span>NULL</span><span> , </span><span>14</span> b <span>INT</span> <span>NOT</span> <span>NULL</span> <span>15</span> <span> ) </span><span>16</span> <span>GO</span> <span>17</span> <span>18</span> <span>--</span><span>这里一定要是唯一的</span> <span>19</span> <span>CREATE</span> <span>UNIQUE</span> <span>CLUSTERED</span> <span>INDEX</span> ucl <span>ON</span><span> testcluster(b) </span><span>20</span> <span>GO</span> <span>21</span> <span>22</span> <span>INSERT</span><span> testcluster </span><span>23</span> <span>SELECT</span> <span>CAST</span>(<span>11</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>1</span> <span>UNION</span> <span>ALL</span> <span>24</span> <span>SELECT</span> <span>CAST</span>(<span>22</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>2</span>View Code
查看表情况的脚本
<span> 1</span> <span>CREATE</span> <span>TABLE</span><span> DBCCResult ( </span><span> 2</span> PageFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span> 3</span> PagePID <span>NVARCHAR</span>(<span>200</span><span>), </span><span> 4</span> IAMFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span> 5</span> IAMPID <span>NVARCHAR</span>(<span>200</span><span>), </span><span> 6</span> ObjectID <span>NVARCHAR</span>(<span>200</span><span>), </span><span> 7</span> IndexID <span>NVARCHAR</span>(<span>200</span><span>), </span><span> 8</span> PartitionNumber <span>NVARCHAR</span>(<span>200</span><span>), </span><span> 9</span> PartitionID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>10</span> iam_chain_type <span>NVARCHAR</span>(<span>200</span><span>), </span><span>11</span> PageType <span>NVARCHAR</span>(<span>200</span><span>), </span><span>12</span> IndexLevel <span>NVARCHAR</span>(<span>200</span><span>), </span><span>13</span> NextPageFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>14</span> NextPagePID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>15</span> PrevPageFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>16</span> PrevPagePID <span>NVARCHAR</span>(<span>200</span><span>) </span><span>17</span> <span>) </span><span>18</span> <span>19</span> <span>TRUNCATE</span> <span>TABLE</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span>20</span> <span>21</span> <span>INSERT</span> <span>INTO</span> DBCCResult <span>EXEC</span> (<span>'</span><span>DBCC IND(testhashkey,testcluster,-1) </span><span>'</span><span>) </span><span>22</span> <span>23</span> <span>SELECT</span> <span>*</span> <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>PageType</span><span>]</span> <span>DESC</span>View Code
聚集索引页面
其实我这里暂时还不清楚聚集索引页面的KeyHashValue有什么作用，为什麽这样说？？请往下看
我们看一下表中的每行记录的所产生的keyhashvalue
<span>1</span> <span>select</span> <span>%%</span>lockres<span>%%</span> <span>AS</span> <span>'</span><span>数据页的keyhashvalue</span><span>'</span> <span>from</span> testcluster
大家可以看到，无论是索引行还是数据行都有KeyHashValue
我们使用下面语句进行测试，查看SQLSERVER锁定的资源
<span> 1</span> <span>SET</span> <span>TRANSACTION</span> <span>ISOLATION</span> <span>LEVEL</span> <span>SERIALIZABLE</span> <span> 2</span> <span>GO</span> <span> 3</span> <span>BEGIN</span> <span>TRANSACTION</span> <span> 4</span> <span>SELECT</span> b <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>testcluster</span><span>]</span> <span>WHERE</span> <span>[</span><span>b</span><span>]</span><span>=</span><span>1</span> <span> 5</span> <span>--</span><span>COMMIT TRAN</span> <span> 6</span> <span> 7</span> <span>SELECT</span><span> resource_type , </span><span> 8</span> <span> resource_database_id , </span><span> 9</span> <span> resource_description , </span><span>10</span> <span> resource_associated_entity_id , </span><span>11</span> <span> request_mode , </span><span>12</span> <span> request_type , </span><span>13</span> <span> request_status </span><span>14</span> <span>FROM</span><span> sys.dm_tran_locks </span><span>15</span> <span>WHERE</span> <span>[</span><span>resource_database_id</span><span>]</span><span>=</span><span>DB_ID</span>(<span>'</span><span>testhashkey</span><span>'</span><span>) </span><span>16</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>resource_type</span><span>]</span>View Code
为什麽我刚才说：不清楚聚集索引页面的KeyHashValue有什么作用？？？
大家可以用下面的脚本来测试一下，无论我select还是update，DepartmentID BETWEEN 0 AND 122之间
使用sys.dm_tran_locks视图来查询，发现resource_description字段都没有显示聚集索引页面的keyhashvalue，只显示数据页面
的keyhashvalue，说明我在select和update的时候没有用到聚集索引页面的keyhashvalue，这里我不知道在什么情况下会用到
聚集索引页面的KeyHashValue
脚本如下：
<span> 1</span> <span>USE</span><span> master </span><span> 2</span> <span>GO</span> <span> 3</span> <span>CREATE</span> <span>DATABASE</span><span> practice </span><span> 4</span> <span>GO</span> <span> 5</span> <span> 6</span> <span>USE</span><span> practice </span><span> 7</span> <span>GO</span> <span> 8</span> <span> 9</span> <span>--</span><span>只有聚集索引</span> <span>10</span> <span>CREATE</span> <span>TABLE</span><span> Department( </span><span>11</span> DepartmentID <span>int</span> <span>IDENTITY</span>(<span>1</span>,<span>1</span>) <span>NOT</span> <span>NULL</span> <span>PRIMARY</span> <span>KEY</span><span>, </span><span>12</span> Name <span>NVARCHAR</span>(<span>200</span>) <span>NOT</span> <span>NULL</span><span>, </span><span>13</span> GroupName <span>NVARCHAR</span>(<span>200</span>) <span>NOT</span> <span>NULL</span><span>, </span><span>14</span> Company <span>NVARCHAR</span>(<span>300</span><span>), </span><span>15</span> ModifiedDate <span>datetime</span> <span>NOT</span> <span>NULL</span> <span>DEFAULT</span> (<span>getdate</span><span>()) </span><span>16</span> <span>) </span><span>17</span> <span>18</span> <span>INSERT</span> <span>INTO</span> Department(name,<span>[</span><span>Company</span><span>]</span>,groupname) <span>VALUES</span>(<span>'</span><span>销售部</span><span>'</span>,<span>'</span><span>中国你好有限公司XX分公司</span><span>'</span>,<span>'</span><span>销售组</span><span>'</span><span>) </span><span>19</span> <span>GO</span> <span>100000</span> <span>20</span> <span>21</span> <span>CREATE</span> <span>TABLE</span><span> DBCCResult ( </span><span>22</span> PageFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>23</span> PagePID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>24</span> IAMFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>25</span> IAMPID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>26</span> ObjectID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>27</span> IndexID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>28</span> PartitionNumber <span>NVARCHAR</span>(<span>200</span><span>), </span><span>29</span> PartitionID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>30</span> iam_chain_type <span>NVARCHAR</span>(<span>200</span><span>), </span><span>31</span> PageType <span>NVARCHAR</span>(<span>200</span><span>), </span><span>32</span> IndexLevel <span>NVARCHAR</span>(<span>200</span><span>), </span><span>33</span> NextPageFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>34</span> NextPagePID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>35</span> PrevPageFID <span>NVARCHAR</span>(<span>200</span><span>), </span><span>36</span> PrevPagePID <span>NVARCHAR</span>(<span>200</span><span>) </span><span>37</span> <span>) </span><span>38</span> <span>39</span> <span>TRUNCATE</span> <span>TABLE</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span>40</span> <span>41</span> <span>INSERT</span> <span>INTO</span> DBCCResult <span>EXEC</span> (<span>'</span><span>DBCC IND(practice,Department,-1) </span><span>'</span><span>) </span><span>42</span> <span>43</span> <span>SELECT</span> <span>*</span> <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>PageType</span><span>]</span> <span>DESC</span> <span>44</span> <span>45</span> <span>DBCC</span> TRACEON(<span>3604</span>,<span>-</span><span>1</span><span>) </span><span>46</span> <span>GO</span> <span>47</span> <span>DBCC</span> PAGE(practice,<span>1</span>,<span>114</span>,<span>3</span><span>) </span><span>48</span> <span>GO</span> <span>49</span> <span>50</span> <span>select</span> <span>%%</span>lockres<span>%%</span> <span>AS</span> <span>'</span><span>数据页的keyhashvalue</span><span>'</span> <span>from</span><span> Department </span><span>51</span> <span>52</span> <span>53</span> <span>54</span> <span>55</span> <span>56</span> <span>57</span> <span>SET</span> <span>TRANSACTION</span> <span>ISOLATION</span> <span>LEVEL</span> <span>SERIALIZABLE</span> <span>58</span> <span>GO</span> <span>59</span> <span>BEGIN</span> <span>TRANSACTION</span> <span>60</span> <span>SELECT</span> DepartmentID <span>FROM</span> Department <span>WHERE</span> DepartmentID <span>BETWEEN</span> <span>0</span> <span>AND</span> <span>122</span> <span>61</span> <span>--</span><span>COMMIT TRAN</span> <span>62</span> <span>63</span> <span>SELECT</span><span> resource_type , </span><span>64</span> <span> resource_database_id , </span><span>65</span> <span> resource_description , </span><span>66</span> <span> resource_associated_entity_id , </span><span>67</span> <span> request_mode , </span><span>68</span> <span> request_type , </span><span>69</span> <span> request_status </span><span>70</span> <span>FROM</span><span> sys.dm_tran_locks </span><span>71</span> <span>WHERE</span> <span>[</span><span>resource_database_id</span><span>]</span><span>=</span><span>DB_ID</span>(<span>'</span><span>practice</span><span>'</span><span>) </span><span>72</span> <span>AND</span> <span>[</span><span>resource_description</span><span>]</span> <span>LIKE</span> <span>'</span><span>%b03b%</span><span>'</span> <span>73</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>resource_type</span><span>]</span>View Code
我做了一个大胆的假设：其实聚集索引页面的keyhashvalue是没有用的！！！
原因一：
如果把刚才的脚本在SQL2012下运行，你会发现聚集索引的KeyHashValue列全部为NULL
原因二：
就是我上面的测试脚本，无论我select还是update，DepartmentID BETWEEN 0 AND 122之间
使用sys.dm_tran_locks视图来查询，发现resource_description字段都没有显示聚集索引页面的keyhashvalue，只显示数据页面
的KeyHashValue
原因三：
就是昨天跟高文佳童鞋讨论的时候，他也发现了有时候在聚集索引里也会看到KeyHashValue列全部为NULL
我之前在SQLSERVER2005下也测试过，确实是这样
SQLSERVER中KeyHashValue的作用（上）
原因四：
可能为了不改动代码，原先SQLSERVER团队设计的时候只需要非聚集索引有KeyHashValue就可以了，而聚集索引不需要KeyHashValue的
但是如果是这样，为了减少改动，不写两套代码，或者为了某种兼容性（与前面版本兼容），而不删除聚集索引的KeyHashValue
非聚集索引
非聚集索引表的非聚集索引页有KeyHashValue，但是数据页是没有KeyHashValue的
创建非聚集索引，这里我也是指定唯一的
脚本：
<span> 1</span> <span>--</span><span>测试非聚集索引</span> <span> 2</span> <span>USE</span> <span>[</span><span>testhashkey</span><span>]</span> <span> 3</span> <span>GO</span> <span> 4</span> <span>CREATE</span> <span>TABLE</span><span> testnoncluster </span><span> 5</span> <span> ( </span><span> 6</span> a <span>NVARCHAR</span>(<span>3800</span>) <span>NOT</span> <span>NULL</span><span> , </span><span> 7</span> b <span>INT</span> <span>NOT</span> <span>NULL</span> <span> 8</span> <span> ) </span><span> 9</span> <span>GO</span> <span>10</span> <span>11</span> <span>CREATE</span> <span>UNIQUE</span> <span>NONCLUSTERED</span> <span>INDEX</span> ucil <span>ON</span><span> testnoncluster(b) </span><span>12</span> <span>GO</span> <span>13</span> <span>14</span> <span>INSERT</span><span> testnoncluster </span><span>15</span> <span>SELECT</span> <span>CAST</span>(<span>11</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>1</span> <span>UNION</span> <span>ALL</span> <span>16</span> <span>SELECT</span> <span>CAST</span>(<span>22</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>2</span> <span>17</span> <span>18</span> <span>19</span> <span>SELECT</span> <span>*</span> <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>testnoncluster</span><span>]</span>View Code
查看表情况的脚本
<span> 1</span> <span>TRUNCATE</span> <span>TABLE</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span> 2</span> <span> 3</span> <span>INSERT</span> <span>INTO</span> DBCCResult <span>EXEC</span> (<span>'</span><span>DBCC IND(testhashkey,testnoncluster,-1) </span><span>'</span><span>) </span><span> 4</span> <span> 5</span> <span>SELECT</span> <span>*</span> <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>PageType</span><span>]</span> <span>DESC</span> <span> 6</span> <span> 7</span> <span>DBCC</span> TRACEON(<span>3604</span>,<span>-</span><span>1</span><span>) </span><span> 8</span> <span>GO</span> <span> 9</span> <span>DBCC</span> PAGE(testhashkey,<span>1</span>,<span>77</span>,<span>3</span><span>) </span><span>10</span> <span>GO</span>View Code
非聚集索引页面
我们看一下表中的每行记录的所产生的keyhashvalue
<span>1</span> <span>select</span> <span>%%</span>lockres<span>%%</span> <span>AS</span> <span>'</span><span>数据页的keyhashvalue</span><span>'</span> <span>from</span> testnoncluster
大家可以看到，这里只显示了行记录的FID:PID:RID，并没有显示keyhashvalue
我们使用下面语句进行测试，查看SQLSERVER锁定的资源
<span> 1</span> <span>SET</span> <span>TRANSACTION</span> <span>ISOLATION</span> <span>LEVEL</span> <span>SERIALIZABLE</span> <span> 2</span> <span>GO</span> <span> 3</span> <span>BEGIN</span> <span>TRANSACTION</span> <span> 4</span> <span>SELECT</span> b <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>testnoncluster</span><span>]</span> <span>WHERE</span> <span>[</span><span>b</span><span>]</span><span>=</span><span>1</span> <span> 5</span> <span>--</span><span>COMMIT TRAN</span> <span> 6</span> <span> 7</span> <span>SELECT</span><span> resource_type , </span><span> 8</span> <span> resource_database_id , </span><span> 9</span> <span> resource_description , </span><span>10</span> <span> resource_associated_entity_id , </span><span>11</span> <span> request_mode , </span><span>12</span> <span> request_type , </span><span>13</span> <span> request_status </span><span>14</span> <span>FROM</span><span> sys.dm_tran_locks </span><span>15</span> <span>WHERE</span> <span>[</span><span>resource_database_id</span><span>]</span><span>=</span><span>DB_ID</span>(<span>'</span><span>testhashkey</span><span>'</span><span>) </span><span>16</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>resource_type</span><span>]</span>View Code
我们使用下面脚本创建一个非聚集索引表testnoncluster2
<span> 1</span> <span>--</span><span>测试堆表和非聚集索引表的数据页也有keyhashvalue</span> <span> 2</span> <span>USE</span> <span>[</span><span>testhashkey</span><span>]</span> <span> 3</span> <span>GO</span> <span> 4</span> <span> 5</span> <span> 6</span> <span>CREATE</span> <span>TABLE</span><span> testnoncluster2 </span><span> 7</span> <span> ( </span><span> 8</span> a <span>NVARCHAR</span>(<span>3800</span>) <span>NOT</span> <span>NULL</span><span> , </span><span> 9</span> b <span>INT</span> <span>NOT</span> <span>NULL</span><span>, </span><span>10</span> c <span>INT</span> <span>NOT</span> <span>NULL</span> <span>11</span> <span> ) </span><span>12</span> <span>GO</span> <span>13</span> <span>14</span> <span>15</span> <span>16</span> <span>CREATE</span> <span>UNIQUE</span> <span>NONCLUSTERED</span> <span>INDEX</span> ucil <span>ON</span><span> testnoncluster2(b) </span><span>17</span> <span>GO</span> <span>18</span> <span>19</span> <span>INSERT</span><span> testnoncluster2 </span><span>20</span> <span>SELECT</span> <span>CAST</span>(<span>11</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>1</span>,<span>1</span> <span>UNION</span> <span>ALL</span> <span>21</span> <span>SELECT</span> <span>CAST</span>(<span>22</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>2</span>,<span>2</span> <span>22</span> <span>23</span> <span>24</span> <span>25</span> <span>SET</span> <span>TRANSACTION</span> <span>ISOLATION</span> <span>LEVEL</span> <span>SERIALIZABLE</span> <span>26</span> <span>GO</span> <span>27</span> <span>BEGIN</span> <span>TRANSACTION</span> <span>28</span> <span>DELETE</span> <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>testnoncluster2</span><span>]</span> <span>WHERE</span> <span>[</span><span>c</span><span>]</span><span>=</span><span>1</span> <span>29</span> <span>--</span><span>ROLLBACK TRAN</span> <span>30</span> <span>31</span> <span>SELECT</span><span> resource_type , </span><span>32</span> <span> resource_database_id , </span><span>33</span> <span> resource_description , </span><span>34</span> <span> resource_associated_entity_id , </span><span>35</span> <span> request_mode , </span><span>36</span> <span> request_type , </span><span>37</span> <span> request_status </span><span>38</span> <span>FROM</span><span> sys.dm_tran_locks </span><span>39</span> <span>WHERE</span> <span>[</span><span>resource_database_id</span><span>]</span><span>=</span><span>DB_ID</span>(<span>'</span><span>testhashkey</span><span>'</span><span>) </span><span>40</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>resource_type</span><span>]</span> <span>41</span> <span>42</span> <span>43</span> <span>44</span> <span>45</span> <span>select</span> <span>%%</span>lockres<span>%%</span> <span>AS</span> <span>'</span><span>数据页的keyhashvalue</span><span>'</span> <span>from</span> testnoncluster2View Code
这次删除非聚集索引表的一行
为了保证我的结论的正确性，我在SQLSERVER2012里也用上面的脚本测试了一下，创建了表testnoncluster2
脚本：
<span> 1</span> <span>--</span><span>测试堆表和非聚集索引表的数据页也有keyhashvalue</span> <span> 2</span> <span>USE</span> <span>[</span><span>testhashkey</span><span>]</span> <span> 3</span> <span>GO</span> <span> 4</span> <span> 5</span> <span> 6</span> <span> 7</span> <span>CREATE</span> <span>TABLE</span><span> testnoncluster2 </span><span> 8</span> <span> ( </span><span> 9</span> a <span>NVARCHAR</span>(<span>3800</span>) <span>NOT</span> <span>NULL</span><span> , </span><span>10</span> b <span>INT</span> <span>NOT</span> <span>NULL</span><span>, </span><span>11</span> c <span>INT</span> <span>NOT</span> <span>NULL</span> <span>12</span> <span> ) </span><span>13</span> <span>GO</span> <span>14</span> <span>15</span> <span>16</span> <span>17</span> <span>CREATE</span> <span>UNIQUE</span> <span>NONCLUSTERED</span> <span>INDEX</span> ucil <span>ON</span><span> testnoncluster2(b) </span><span>18</span> <span>GO</span> <span>19</span> <span>20</span> <span>INSERT</span><span> testnoncluster2 </span><span>21</span> <span>SELECT</span> <span>CAST</span>(<span>11</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>1</span>,<span>1</span> <span>UNION</span> <span>ALL</span> <span>22</span> <span>SELECT</span> <span>CAST</span>(<span>22</span> <span>AS</span> <span>VARCHAR</span>(<span>10</span>))<span>+</span><span>replicate</span>(<span>'</span><span>a</span><span>'</span>, <span>3500</span>),<span>2</span>,<span>2</span> <span>23</span> <span>24</span> <span>25</span> <span>26</span> <span>27</span> <span>28</span> <span>TRUNCATE</span> <span>TABLE</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span>29</span> <span>30</span> <span>INSERT</span> <span>INTO</span> DBCCResult <span>EXEC</span> (<span>'</span><span>DBCC IND(testhashkey,testnoncluster2,-1) </span><span>'</span><span>) </span><span>31</span> <span>32</span> <span>SELECT</span> <span>*</span> <span>FROM</span> <span>[</span><span>dbo</span><span>]</span>.<span>[</span><span>DBCCResult</span><span>]</span> <span>ORDER</span> <span>BY</span> <span>[</span><span>PageType</span><span>]</span> <span>DESC</span> <span>33</span> <span>34</span> <span>DBCC</span> TRACEON(<span>3604</span>,<span>-</span><span>1</span><span>) </span><span>35</span> <span>GO</span> <span>36</span> <span>DBCC</span> PAGE(testhashkey,<span>1</span>,<span>165</span>,<span>3</span><span>) </span><span>37</span> <span>GO</span>View Code
数据页面165
<span> 1</span> <span>DBCC</span> 执行完毕。如果 <span>DBCC</span><span> 输出了错误信息，请与系统管理员联系。 </span><span> 2</span> <span> 3</span> PAGE: (<span>1</span>:<span>165</span><span>) </span><span> 4</span> <span> 5</span> <span> 6</span> <span>BUFFER: </span><span> 7</span> <span> 8</span> <span> 9</span> BUF <span>@0x049D10A8</span> <span> 10</span> <span> 11</span> bpage <span>=</span> <span>0x14784000</span> bhash <span>=</span> <span>0x00000000</span> bpageno <span>=</span> (<span>1</span>:<span>165</span><span>) </span><span> 12</span> bdbid <span>=</span> <span>7</span> breferences <span>=</span> <span>0</span> bcputicks <span>=</span> <span>0</span> <span> 13</span> bsampleCount <span>=</span> <span>0</span> bUse1 <span>=</span> <span>23721</span> bstat <span>=</span> <span>0xb</span> <span> 14</span> blog <span>=</span> <span>0xdb215acc</span> bnext <span>=</span> <span>0x00000000</span> <span> 15</span> <span> 16</span> <span>PAGE HEADER: </span><span> 17</span> <span> 18</span> <span> 19</span> Page <span>@0x14784000</span> <span> 20</span> <span> 21</span> m_pageId <span>=</span> (<span>1</span>:<span>165</span>) m_headerVersion <span>=</span> <span>1</span> m_type <span>=</span> <span>1</span> <span> 22</span> m_typeFlagBits <span>=</span> <span>0x0</span> m_level <span>=</span> <span>0</span> m_flagBits <span>=</span> <span>0x8000</span> <span> 23</span> m_objId (AllocUnitId.idObj) <span>=</span> <span>90</span> m_indexId (AllocUnitId.idInd) <span>=</span> <span>256</span> <span> 24</span> Metadata: AllocUnitId <span>=</span> <span>72057594043826176</span> <span> 25</span> Metadata: PartitionId <span>=</span> <span>72057594039238656</span> Metadata: IndexId <span>=</span> <span>0</span> <span> 26</span> Metadata: ObjectId <span>=</span> <span>629577281</span> m_prevPage <span>=</span> (<span>0</span>:<span>0</span>) m_nextPage <span>=</span> (<span>0</span>:<span>0</span><span>) </span><span> 27</span> pminlen <span>=</span> <span>12</span> m_slotCnt <span>=</span> <span>1</span> m_freeCnt <span>=</span> <span>1071</span> <span> 28</span> m_freeData <span>=</span> <span>7119</span> m_reservedCnt <span>=</span> <span>0</span> m_lsn <span>=</span> (<span>35</span>:<span>211</span>:<span>62</span><span>) </span><span> 29</span> m_xactReserved <span>=</span> <span>0</span> m_xdesId <span>=</span> (<span>0</span>:<span>0</span>) m_ghostRecCnt <span>=</span> <span>0</span> <span> 30</span> m_tornBits <span>=</span> <span>0</span> DB Frag ID <span>=</span> <span>1</span> <span> 31</span> <span> 32</span> <span>Allocation Status </span><span> 33</span> <span> 34</span> GAM (<span>1</span>:<span>2</span>) <span>=</span> ALLOCATED SGAM (<span>1</span>:<span>3</span>) <span>=</span><span> ALLOCATED </span><span> 35</span> PFS (<span>1</span>:<span>1</span>) <span>=</span> <span>0x63</span> MIXED_EXT ALLOCATED 95_PCT_FULL DIFF (<span>1</span>:<span>6</span>) <span>=</span><span> CHANGED </span><span> 36</span> ML (<span>1</span>:<span>7</span>) <span>=</span> <span>NOT</span><span> MIN_LOGGED </span><span> 37</span> <span> 38</span> Slot <span>0</span> Offset <span>0x60</span> Length <span>7023</span> <span> 39</span> <span> 40</span> Record Type <span>=</span> PRIMARY_RECORD Record Attributes <span>=</span><span> NULL_BITMAP VARIABLE_COLUMNS </span><span> 41</span> Record Size <span>=</span> <span>7023</span> <span> 42</span> Memory <span>Dump</span> <span>@0x0FB7C060</span> <span> 43</span> <span> 44</span> <span>00000000</span>: 30000c00 <span>01000000</span> <span>01000000</span> <span>03000001</span> 006f1b31 <span>0</span>................o.<span>1</span> <span> 45</span> <span>00000014</span>: <span>00310061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> .<span>1</span><span>.a.a.a.a.a.a.a.a.a </span><span> 46</span> <span>00000028</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 47</span> 0000003C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 48</span> <span>00000050</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 49</span> <span>00000064</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 50</span> <span>00000078</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 51</span> 0000008C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 52</span> 000000A0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 53</span> 000000B4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 54</span> 000000C8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 55</span> 000000DC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 56</span> 000000F0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 57</span> <span>00000104</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 58</span> <span>00000118</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 59</span> 0000012C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 60</span> <span>00000140</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 61</span> <span>00000154</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 62</span> <span>00000168</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 63</span> 0000017C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 64</span> <span>00000190</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 65</span> 000001A4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 66</span> 000001B8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 67</span> 000001CC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 68</span> 000001E0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 69</span> 000001F4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 70</span> <span>00000208</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 71</span> 0000021C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 72</span> <span>00000230</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 73</span> <span>00000244</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 74</span> <span>00000258</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 75</span> 0000026C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 76</span> <span>00000280</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 77</span> <span>00000294</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 78</span> 000002A8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 79</span> 000002BC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 80</span> 000002D0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 81</span> 000002E4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 82</span> 000002F8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 83</span> 0000030C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 84</span> <span>00000320</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 85</span> <span>00000334</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 86</span> <span>00000348</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 87</span> 0000035C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 88</span> <span>00000370</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 89</span> <span>00000384</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 90</span> <span>00000398</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 91</span> 000003AC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 92</span> 000003C0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 93</span> 000003D4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 94</span> 000003E8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 95</span> 000003FC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 96</span> <span>00000410</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 97</span> <span>00000424</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 98</span> <span>00000438</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span> 99</span> 0000044C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>100</span> <span>00000460</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>101</span> <span>00000474</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>102</span> <span>00000488</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>103</span> 0000049C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>104</span> 000004B0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>105</span> 000004C4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>106</span> 000004D8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>107</span> 000004EC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>108</span> <span>00000500</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>109</span> <span>00000514</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>110</span> <span>00000528</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>111</span> 0000053C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>112</span> <span>00000550</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>113</span> <span>00000564</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>114</span> <span>00000578</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>115</span> 0000058C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>116</span> 000005A0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>117</span> 000005B4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>118</span> 000005C8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>119</span> 000005DC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>120</span> 000005F0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>121</span> <span>00000604</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>122</span> <span>00000618</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>123</span> 0000062C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>124</span> <span>00000640</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>125</span> <span>00000654</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>126</span> <span>00000668</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>127</span> 0000067C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>128</span> <span>00000690</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>129</span> 000006A4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>130</span> 000006B8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>131</span> 000006CC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>132</span> 000006E0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>133</span> 000006F4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>134</span> <span>00000708</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>135</span> 0000071C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>136</span> <span>00000730</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>137</span> <span>00000744</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>138</span> <span>00000758</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>139</span> 0000076C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>140</span> <span>00000780</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>141</span> <span>00000794</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>142</span> 000007A8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>143</span> 000007BC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>144</span> 000007D0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>145</span> 000007E4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>146</span> 000007F8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>147</span> 0000080C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>148</span> <span>00000820</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>149</span> <span>00000834</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>150</span> <span>00000848</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>151</span> 0000085C: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>152</span> <span>00000870</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>153</span> <span>00000884</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>154</span> <span>00000898</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>155</span> 000008AC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>156</span> 000008C0: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>157</span> 000008D4: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>158</span> 000008E8: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>159</span> 000008FC: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>160</span> <span>00000910</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>161</span> <span>00000924</span>: <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span> <span>00610061</span><span> .a.a.a.a.a.a.a.a.a.a </span><span>162</span> <span>00000938</span>: <span>00610061</span> <span>00610061</span>
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mysql：简单的概念，用于轻松学习Apr 10, 2025 am 09:29 AMMySQL是一个开源的关系型数据库管理系统。1）创建数据库和表：使用CREATEDATABASE和CREATETABLE命令。2）基本操作：INSERT、UPDATE、DELETE和SELECT。3）高级操作：JOIN、子查询和事务处理。4）调试技巧：检查语法、数据类型和权限。5）优化建议：使用索引、避免SELECT*和使用事务。
MySQL：数据库的用户友好介绍Apr 10, 2025 am 09:27 AMMySQL的安装和基本操作包括：1.下载并安装MySQL，设置根用户密码；2.使用SQL命令创建数据库和表，如CREATEDATABASE和CREATETABLE；3.执行CRUD操作，使用INSERT,SELECT,UPDATE,DELETE命令；4.创建索引和存储过程以优化性能和实现复杂逻辑。通过这些步骤，你可以从零开始构建和管理MySQL数据库。
InnoDB缓冲池如何工作，为什么对性能至关重要？Apr 09, 2025 am 12:12 AMInnoDBBufferPool通过将数据和索引页加载到内存中来提升MySQL数据库的性能。1)数据页加载到BufferPool中，减少磁盘I/O。2)脏页被标记并定期刷新到磁盘。3)LRU算法管理数据页淘汰。4)预读机制提前加载可能需要的数据页。
MySQL：初学者的数据管理易用性Apr 09, 2025 am 12:07 AMMySQL适合初学者使用，因为它安装简单、功能强大且易于管理数据。1.安装和配置简单，适用于多种操作系统。2.支持基本操作如创建数据库和表、插入、查询、更新和删除数据。3.提供高级功能如JOIN操作和子查询。4.可以通过索引、查询优化和分表分区来提升性能。5.支持备份、恢复和安全措施，确保数据的安全和一致性。
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