解剖SQLSERVER 第十七篇 使用 OrcaMDF Corruptor 故意损坏数据库(译) http://improve.dk/corrupting-databases-purpose-using-orcamdf-corruptor/ 有时候你必须先作恶,后行善。情况就是 当你想磨练你的数据库修复技能 我现在添加了一个Corruptor 类到Orca
解剖SQLSERVER 第十七篇 使用 OrcaMDF Corruptor 故意损坏数据库(译)
http://improve.dk/corrupting-databases-purpose-using-orcamdf-corruptor/
有时候你必须先作恶,后行善。情况就是 当你想磨练你的数据库修复技能
我现在添加了一个Corruptor 类到OrcaMDF里面 去测试新的RawDatabase 的功能。Corruptor 就跟他的名字一样--他会故意损坏数据库文件
Corruptor 本身是比较简单的。Corruptor 会随机选择一些页面并且简单的使用0来完全复写页面。
根据页面的类型,这可能会造成致命伤害
我不想多说什么了,不过万一。。。请不要在你的生产库上运行。这会损坏你的数据。
例子
有两个 Corruptor.CorruptFile重载方法,他们都返回integers 的枚举值 -- 一系列的pageid 列表并且被复写0的
下面的代码会损坏5%的页面在AdventureWorks2008R2LT.mdf 文件里面,然后他会输出每个被损坏了的页面ID 。
你可以定义损坏页面的百分比 只需要改变第二个参数
<span>var</span> corruptedPageIDs = Corruptor.CorruptFile(<span>@"</span><span>C:\AdventureWorks2008R2LT.mdf</span><span>"</span>, <span>0.05</span><span>); Console.WriteLine(</span><span>string</span>.Join(<span>"</span><span>, </span><span>"</span>, corruptedPageIDs));
<span>606</span>, <span>516</span>, <span>603</span>, <span>521</span>, <span>613</span>, <span>621</span>, <span>118</span>, <span>47</span>, <span>173</span>, <span>579</span><span>, </span><span>323</span>, <span>217</span>, <span>358</span>, <span>515</span>, <span>615</span>, <span>271</span>, <span>176</span>, <span>596</span>, <span>417</span>, <span>379</span><span>, </span><span>269</span>, <span>409</span>, <span>558</span>, <span>103</span>, <span>8</span>, <span>636</span>, <span>200</span>, <span>361</span>, <span>60</span>, <span>486</span><span>, </span><span>366</span>, <span>99</span>, <span>87</span>
为了使损坏更厉害,你也可以使用第二个重载方法,他允许你定义一个确切的损坏页面的数目,在一个确定的pageid范围内。
下面的代码会确切的损坏pageid在0到49这个范围内的10个页面,因此会损坏大部分的元数据,大家知道系统表的数据基本都存储在数据库最靠前的页面上
<span>var</span> corruptedPageIDs = Corruptor.CorruptFile(<span>@"</span><span>C:\AdventureWorks2008R2LT.mdf</span><span>"</span>, <span>10</span>, <span>0</span>, <span>49</span><span>); Console.WriteLine(</span><span>string</span>.Join(<span>"</span><span>, </span><span>"</span>, corruptedPageIDs));
<span>16</span>, <span>4</span>, <span>0</span>, <span>32</span>, <span>15</span>, <span>14</span>, <span>30</span>, <span>2</span>, <span>49</span>, <span>9</span>
在上面的情况我非常不幸的看到 下面这些页面都被填充了0 包括:
file header page,page 2 is the first GAM page,page 9 is the boot page ,page 16 allocation unit metadata。
这样的损坏程度,即使使用DBCC CHECKDB也没办法修复,留下给你的选择只有从备份中还原
或者,你可以尝试一下使用OrcaMDF RawDatabase去恢复尽可能多的数据,先到这里了,我以后还会继续介绍。
<span>DBCC</span> TRACEON(<span>3604</span>,<span>-</span><span>1</span><span>) </span><span>GO</span> <span>DBCC</span> PAGE(<span>[</span><span>sss</span><span>]</span>,<span>1</span>,<span>16</span>,<span>3</span><span>) </span><span>GO</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。 PAGE: (</span><span>1</span>:<span>16</span><span>) BUFFER: BUF </span><span>@0x0000000080FDEB80</span><span> bpage </span><span>=</span> <span>0x0000000080A74000</span> bhash <span>=</span> <span>0x0000000000000000</span> bpageno <span>=</span> (<span>1</span>:<span>16</span><span>) bdbid </span><span>=</span> <span>8</span> breferences <span>=</span> <span>0</span> bcputicks <span>=</span> <span>0</span><span> bsampleCount </span><span>=</span> <span>0</span> bUse1 <span>=</span> <span>19980</span> bstat <span>=</span> <span>0xc00009</span><span> blog </span><span>=</span> <span>0x32159</span> bnext <span>=</span> <span>0x0000000000000000</span><span> PAGE HEADER: Page </span><span>@0x0000000080A74000</span><span> m_pageId </span><span>=</span> (<span>1</span>:<span>16</span>) m_headerVersion <span>=</span> <span>1</span> m_type <span>=</span> <span>1</span><span> m_typeFlagBits </span><span>=</span> <span>0x4</span> m_level <span>=</span> <span>0</span> m_flagBits <span>=</span> <span>0x200</span><span> m_objId (AllocUnitId.idObj) </span><span>=</span> <span>7</span> m_indexId (AllocUnitId.idInd) <span>=</span> <span>0</span> Metadata: AllocUnitId <span>=</span> <span>458752</span><span> Metadata: PartitionId </span><span>=</span> <span>458752</span> Metadata: IndexId <span>=</span> <span>1</span> Metadata: ObjectId <span>=</span> <span>7</span><span> m_prevPage </span><span>=</span> (<span>0</span>:<span>0</span>) m_nextPage <span>=</span> (<span>1</span>:<span>130</span>) pminlen <span>=</span> <span>73</span><span> m_slotCnt </span><span>=</span> <span>49</span> m_freeCnt <span>=</span> <span>4225</span> m_freeData <span>=</span> <span>4331</span><span> m_reservedCnt </span><span>=</span> <span>0</span> m_lsn <span>=</span> (<span>1037</span>:<span>459</span>:<span>3</span>) m_xactReserved <span>=</span> <span>0</span><span> m_xdesId </span><span>=</span> (<span>0</span>:<span>455</span>) m_ghostRecCnt <span>=</span> <span>0</span> m_tornBits <span>=</span> <span>-</span><span>563242027</span><span> Allocation Status GAM (</span><span>1</span>:<span>2</span>) <span>=</span> ALLOCATED SGAM (<span>1</span>:<span>3</span>) <span>=</span> <span>NOT</span><span> ALLOCATED PFS (</span><span>1</span>:<span>1</span>) <span>=</span> <span>0x60</span> MIXED_EXT ALLOCATED 0_PCT_FULL DIFF (<span>1</span>:<span>6</span>) <span>=</span><span> CHANGED ML (</span><span>1</span>:<span>7</span>) <span>=</span> <span>NOT</span><span> MIN_LOGGED Slot </span><span>0</span> Offset <span>0x60</span> Length <span>77</span><span> Record Type </span><span>=</span> PRIMARY_RECORD Record Attributes <span>=</span> NULL_BITMAP Record Size <span>=</span> <span>77</span><span> Memory </span><span>Dump</span> <span>@0x000000000DC7A060</span> <span>0000000000000000</span>: <span>10004900</span> <span>00000300</span> <span>00000000</span> <span>01000003</span><span> †..I............. </span><span>0000000000000010</span>: <span>00000000</span> <span>00000000</span> 0001001f <span>00000001</span><span> †................ </span><span>0000000000000020</span>: <span>00570000</span> <span>00010056</span> <span>00000001</span><span> 000b0000 †.W.....V........ </span><span>0000000000000030</span>: <span>00000000</span> <span>00090000</span> <span>00000000</span> <span>00110000</span><span> †..... .......... </span><span>0000000000000040</span>: <span>00000000</span> <span>00010000</span> 000c0000 <span>00</span><span>††††††††............. Slot </span><span>0</span> <span>Column</span> <span>1</span> Offset <span>0x4</span> Length <span>8</span> Length (physical) <span>8</span><span> auid </span><span>=</span> <span>196608</span><span> Slot </span><span>0</span> <span>Column</span> <span>2</span> Offset <span>0xc</span> Length <span>1</span> Length (physical) <span>1</span><span> type </span><span>=</span> <span>1</span><span> Slot </span><span>0</span> <span>Column</span> <span>3</span> Offset <span>0xd</span> Length <span>8</span> Length (physical) <span>8</span><span> ownerid </span><span>=</span> <span>196608</span><span> Slot </span><span>0</span> <span>Column</span> <span>4</span> Offset <span>0x15</span> Length <span>4</span> Length (physical) <span>4</span><span> status </span><span>=</span> <span>0</span><span> Slot </span><span>0</span> <span>Column</span> <span>5</span> Offset <span>0x19</span> Length <span>2</span> Length (physical) <span>2</span><span> fgid </span><span>=</span> <span>1</span><span> pgfirst </span><span>=</span> <span>[</span><span>Binary data</span><span>]</span> Slot <span>0</span> <span>Column</span> <span>6</span> Offset <span>0x1b</span> Length <span>6</span> Length (physical) <span>6</span><span> pgfirst </span><span>=</span> <span>0x1f0000000100</span><span> pgroot </span><span>=</span> <span>[</span><span>Binary data</span><span>]</span> Slot <span>0</span> <span>Column</span> <span>7</span> Offset <span>0x21</span> Length <span>6</span> Length (physical) <span>6</span><span> pgroot </span><span>=</span> <span>0x570000000100</span><span> pgfirstiam </span><span>=</span> <span>[</span><span>Binary data</span><span>]</span> Slot <span>0</span> <span>Column</span> <span>8</span> Offset <span>0x27</span> Length <span>6</span> Length (physical) <span>6</span><span> pgfirstiam </span><span>=</span> <span>0x560000000100</span><span> Slot </span><span>0</span> <span>Column</span> <span>9</span> Offset <span>0x2d</span> Length <span>8</span> Length (physical) <span>8</span><span> pcused </span><span>=</span> <span>11</span><span> Slot </span><span>0</span> <span>Column</span> <span>10</span> Offset <span>0x35</span> Length <span>8</span> Length (physical) <span>8</span><span> pcdata </span><span>=</span> <span>9</span><span> Slot </span><span>0</span> <span>Column</span> <span>11</span> Offset <span>0x3d</span> Length <span>8</span> Length (physical) <span>8</span><span> pcreserved </span><span>=</span> <span>17</span><span> Slot </span><span>0</span> <span>Column</span> <span>12</span> Offset <span>0x45</span> Length <span>4</span> Length (physical) <span>4</span><span> dbfragid </span><span>=</span> <span>1</span><span> Slot </span><span>0</span> Offset <span>0x0</span> Length <span>0</span> Length (physical) <span>0</span><span> KeyHashValue </span><span>=</span> (016862d84319)
SELECT COUNT(*) FROM sys.[allocation_units]
--131
SELECT * FROM sys.[allocation_units]
SELECT * FROM sys.[system_internals_allocation_units]
存储在数据库1:16页面上(是[sys.system_internals_allocation_units]系统表)《深入解析sql2008》
第十七篇完

The main difference between MySQL and SQLite is the design concept and usage scenarios: 1. MySQL is suitable for large applications and enterprise-level solutions, supporting high performance and high concurrency; 2. SQLite is suitable for mobile applications and desktop software, lightweight and easy to embed.

Indexes in MySQL are an ordered structure of one or more columns in a database table, used to speed up data retrieval. 1) Indexes improve query speed by reducing the amount of scanned data. 2) B-Tree index uses a balanced tree structure, which is suitable for range query and sorting. 3) Use CREATEINDEX statements to create indexes, such as CREATEINDEXidx_customer_idONorders(customer_id). 4) Composite indexes can optimize multi-column queries, such as CREATEINDEXidx_customer_orderONorders(customer_id,order_date). 5) Use EXPLAIN to analyze query plans and avoid

Using transactions in MySQL ensures data consistency. 1) Start the transaction through STARTTRANSACTION, and then execute SQL operations and submit it with COMMIT or ROLLBACK. 2) Use SAVEPOINT to set a save point to allow partial rollback. 3) Performance optimization suggestions include shortening transaction time, avoiding large-scale queries and using isolation levels reasonably.

Scenarios where PostgreSQL is chosen instead of MySQL include: 1) complex queries and advanced SQL functions, 2) strict data integrity and ACID compliance, 3) advanced spatial functions are required, and 4) high performance is required when processing large data sets. PostgreSQL performs well in these aspects and is suitable for projects that require complex data processing and high data integrity.

The security of MySQL database can be achieved through the following measures: 1. User permission management: Strictly control access rights through CREATEUSER and GRANT commands. 2. Encrypted transmission: Configure SSL/TLS to ensure data transmission security. 3. Database backup and recovery: Use mysqldump or mysqlpump to regularly backup data. 4. Advanced security policy: Use a firewall to restrict access and enable audit logging operations. 5. Performance optimization and best practices: Take into account both safety and performance through indexing and query optimization and regular maintenance.

How to effectively monitor MySQL performance? Use tools such as mysqladmin, SHOWGLOBALSTATUS, PerconaMonitoring and Management (PMM), and MySQL EnterpriseMonitor. 1. Use mysqladmin to view the number of connections. 2. Use SHOWGLOBALSTATUS to view the query number. 3.PMM provides detailed performance data and graphical interface. 4.MySQLEnterpriseMonitor provides rich monitoring functions and alarm mechanisms.

The difference between MySQL and SQLServer is: 1) MySQL is open source and suitable for web and embedded systems, 2) SQLServer is a commercial product of Microsoft and is suitable for enterprise-level applications. There are significant differences between the two in storage engine, performance optimization and application scenarios. When choosing, you need to consider project size and future scalability.

In enterprise-level application scenarios that require high availability, advanced security and good integration, SQLServer should be chosen instead of MySQL. 1) SQLServer provides enterprise-level features such as high availability and advanced security. 2) It is closely integrated with Microsoft ecosystems such as VisualStudio and PowerBI. 3) SQLServer performs excellent in performance optimization and supports memory-optimized tables and column storage indexes.


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