突然收到MySQL報(bào)警，從庫的數(shù)據(jù)庫掛了，一直在不停的重啟，打開錯(cuò)誤日志，發(fā)現(xiàn)有張表壞了。innodb表損壞不能通過repair table 等修復(fù)myisam的命令操作。現(xiàn)在記錄下解決過程，下次遇到就不會(huì)這么手忙腳亂了。
處理過程：
一遇到報(bào)警之后，直接打開錯(cuò)誤日志，里面的信息：
InnoDB: Database page corruption on disk or a failedInnoDB: file read of page 30506.InnoDB: You may have to recover from a backup.130509 20:33:48 InnoDB: Page dump in ascii and hex (16384 bytes):##很多十六進(jìn)制的代碼…………InnoDB: End of page dump130509 20:37:34 InnoDB: Page checksum 1958578898, prior-to-4.0.14-form checksum 3765017239InnoDB: stored checksum 3904709694, prior-to-4.0.14-form stored checksum 3765017239InnoDB: Page lsn 5 614270220, low 4 bytes of lsn at page end 614270220InnoDB: Page number (if stored to page already) 30506,InnoDB: space id (if created with >= MySQL-4.1.1 and stored already) 19InnoDB: Page may be an index page where index id is 54InnoDB: (index "PRIMARY" of table "maitem"."email_status")InnoDB: Database page corruption on disk or a failedInnoDB: file read of page 30506.InnoDB: You may have to recover from a backup.InnoDB: It is also possible that your operatingInnoDB: system has corrupted its own file cacheInnoDB: and rebooting your computer removes theInnoDB: error.InnoDB: If the corrupt page is an index pageInnoDB: you can also try to fix the corruptionInnoDB: by dumping, dropping, and reimportingInnoDB: the corrupt table. You can use CHECKInnoDB: TABLE to scan your table for corruption.InnoDB: See also InnoDB: about forcing recovery.InnoDB: A new raw disk partition was initialized orInnoDB: innodb_force_recovery is on: we do not allowInnoDB: database modifications by the user. Shut downInnoDB: mysqld and edit my.cnf so that newraw is replacedInnoDB: with raw, and innodb_force_... is removed.130509 20:39:35 [Warning] Invalid (old?) table or database name '#sql2-19c4-5'從錯(cuò)誤日志里面很清楚的知道哪里出現(xiàn)了問題，該怎么處理。這時(shí)候數(shù)據(jù)庫隔幾s就重啟，所以差不多可以說你是訪問不了數(shù)據(jù)庫的。所以馬上想到要修復(fù)innodb表了。
以前在Performance的blog上看過類似文章。
當(dāng)時(shí)想到的是在修復(fù)之前保證數(shù)據(jù)庫正常，不是這么異常的無休止的重啟。所以就修改了配置文件的一個(gè)參數(shù)：innodb_force_recovery
innodb_force_recovery影響整個(gè)InnoDB存儲(chǔ)引擎的恢復(fù)狀況。默認(rèn)為0，表示當(dāng)需要恢復(fù)時(shí)執(zhí)行所有的innodb_force_recovery可以設(shè)置為1-6,大的數(shù)字包含前面所有數(shù)字的影響。當(dāng)設(shè)置參數(shù)值大于0后，可以對表進(jìn)行select,create,drop操作,但insert,update或者delete這類操作是不允許的。1(SRV_FORCE_IGNORE_CORRUPT):忽略檢查到的corrupt頁。2(SRV_FORCE_NO_BACKGROUND):阻止主線程的運(yùn)行，如主線程需要執(zhí)行full purge操作，會(huì)導(dǎo)致crash。3(SRV_FORCE_NO_TRX_UNDO):不執(zhí)行事務(wù)回滾操作。4(SRV_FORCE_NO_IBUF_MERGE):不執(zhí)行插入緩沖的合并操作。5(SRV_FORCE_NO_UNDO_LOG_SCAN):不查看重做日志，InnoDB存儲(chǔ)引擎會(huì)將未提交的事務(wù)視為已提交。6(SRV_FORCE_NO_LOG_REDO):不執(zhí)行前滾的操作。因?yàn)殄e(cuò)誤日志里面提示出現(xiàn)了壞頁，導(dǎo)致數(shù)據(jù)庫崩潰，所以這里把innodb_force_recovery 設(shè)置為1，忽略檢查到的壞頁。重啟數(shù)據(jù)庫之后，正常了，沒有出現(xiàn)上面的錯(cuò)誤信息。找到錯(cuò)誤信息出現(xiàn)的表：
(index "PRIMARY" of table "maitem"."email_status")
數(shù)據(jù)頁面的主鍵索引(clustered key index)被損壞。這種情況和數(shù)據(jù)的二級索引(secondary indexes)被損壞相比要糟很多，因?yàn)楹笳呖梢酝ㄟ^使用OPTIMIZE TABLE命令來修復(fù)，但這和更難以恢復(fù)的表格目錄(table dictionary)被破壞的情況來說要好一些。
操作步驟：
因?yàn)楸黄茐牡牡胤街辉谒饕牟糠郑援?dāng)使用innodb_force_recovery = 1運(yùn)行InnoDB時(shí)，操作如下：
執(zhí)行check，repair table 都無效alter table email_status engine =myisam; #也報(bào)錯(cuò)了，因?yàn)槟Ｊ绞莍nnodb_force_recovery =1。ERROR 1025 (HY000): Error on rename of '...' to '....' (errno: -1)建立一張表：create table email_status_bak #和原表結(jié)構(gòu)一樣，只是把INNODB改成了MYISAM。把數(shù)據(jù)導(dǎo)進(jìn)去insert into email_status_bak select * from email_status;刪除掉原表：drop table email_status;注釋掉innodb_force_recovery 之后，重啟。重命名：rename table edm_email_status_bak to email_status;最后該回存儲(chǔ)引擎alter table edm_email_status engine = innodb總結(jié)：
這里的一個(gè)重要知識(shí)點(diǎn)就是 對 innodb_force_recovery 參數(shù)的理解了，要是遇到數(shù)據(jù)損壞甚至是其他的損壞。可能上面的方法不行了，需要嘗試另一個(gè)方法：insert into tb select * from ta limit X；甚至是dump出去，再load回來。
