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這篇文章主要介紹“MySQL Innodb 恢復的方法教程”，在日常操作中，相信很多人在 MySQL Innodb 恢復的方法教程問題上存在疑惑，丸趣 TV 小編查閱了各式資料，整理出簡單好用的操作方法，希望對大家解答”MySQL Innodb 恢復的方法教程”的疑惑有所幫助！接下來，請跟著丸趣 TV 小編一起來學習吧！
MySQL · 引擎特性 · InnoDB 崩潰恢復過程
enum {
SRV_FORCE_IGNORE_CORRUPT = 1, /*! let the server run even if it
detects a corrupt page */
SRV_FORCE_NO_BACKGROUND = 2, /*! prevent the main thread from
running: if a crash would occur
in purge, this prevents it */
SRV_FORCE_NO_TRX_UNDO = 3, /*! do not run trx rollback after
recovery */
SRV_FORCE_NO_IBUF_MERGE = 4, /*! prevent also ibuf operations:
if they would cause a crash, better
not do them */
SRV_FORCE_NO_UNDO_LOG_SCAN = 5, /*! do not look at undo logs when
starting the database: InnoDB will
treat even incomplete transactions
as committed */
SRV_FORCE_NO_LOG_REDO = 6 /*! do not do the log roll-forward
in connection with recovery */};innodb 中的 3 個 lsn
innodb 的 lsn 和 oracle 的 scn 一樣，是一個重要的概念。比如
在 flush list 中正是是使用 low lsn 作為鏈表的條件
參考 buf_page_t 中的 lsn_t oldest_modification;
在 checkpoint 中記錄的也是 lsn
參考宏
#define LOG_CHECKPOINT_NO 0#define LOG_CHECKPOINT_LSN 8#define LOG_CHECKPOINT_OFFSET 16#define LOG_CHECKPOINT_LOG_BUF_SIZE 24在物理文件中每個塊最后的刷新 lsn
參考宏 FIL_PAGE_LSN
在寫日志落盤的時候也是以 lsn 為標準的
參考函數 log_write_up_to
實際上 lsn 就是表示的日志量的字節數，是一個累加的值，在 5.7 中表現為:
/* Type used for all log sequence number storage and arithmetics */typedef ib_uint64_t lsn_t;及一個 8 字節非負的整數。最大值及 2 的 64 次方。有了這種物理上概念，lsn 很容易換算為當前日志的偏移量。
下面描述一下和檢查點相關的幾個 lsn
ibdata 第一個塊 FIL 中的 lsn(flush lsn):ibdata 的 26 后面 8 字節是在 innodb 干凈關閉的時候進行更新的，如果不正常關閉不會進行寫入(FIL_PAGE_FILE_FLUSH_LSN)
redolog 中 MLOG_CHECKPOINT 的 lsn: redolog MLOG_CHECKPOINT lsn 的寫入是在每次 checkpoint 的時候同步寫入的. 干凈關閉會更新。
redolog header 中的 lsn: 是在每次 checkpoint 的時候異步寫入的在 MLOG_CHECKPOINT 寫入之后. 干凈關閉會更新。
我們表示為 lsn1/lsn2/lsn3
正常關閉 3 個 lsn 是相等的，如果非正常關閉 innodb,lsn1 不會更新，因此 lsn3 必然不和 lsn1 相等，則判定需要進行 carsh recovery。
if (checkpoint_lsn != flush_lsn) { ...... if (!recv_needed_recovery) { ib::info() The log sequence number flush_lsn
in the system tablespace does not match
the log sequence number checkpoint_lsn
in the ib_logfiles! // 出現這個警告說明需要恢復了，因為沒有干凈的關閉數據庫，那么 flush_lsn 一定比 checkpoint_lsn 小
if (srv_read_only_mode) { ib::error() Can t initiate database
recovery, running in read-only-mode.
log_mutex_exit(); return(DB_READ_ONLY);
}
recv_init_crash_recovery(); // 初始化
}
}MLOG_CHECKPOINT
log_checkpoint 函數由 master 線程調用，以及關閉數據庫的時候調用，不斷的向 redo log 中寫入 MLOG_CHECKPOINT 和 MLOG_FILE_NAME
log_group_checkpoint 寫入 checkpoint 信息到 log header
#0 mtr_t::commit_checkpoint (this=0x7fff761fb830, checkpoint_lsn=697558445) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/mtr/mtr0mtr.cc:592#1 0x0000000001ceb4b9 in fil_names_clear (lsn=697558445, do_write=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/fil/fil0fil.cc:7067#2 0x0000000001a521cc in log_checkpoint (sync=true, write_always=false) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1927#3 0x0000000001b856f2 in srv_master_do_idle_tasks () at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0srv.cc:2596#4 0x0000000001b85b6b in srv_master_thread (arg=0x0) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0srv.cc:2744#5 0x0000003f74807aa1 in start_thread () from /lib64/libpthread.so.0#6 0x0000003f740e8bcd in clone () from /lib64/libc.so.6正常 innodb 運行的情況下 checkpoint 是由 master 線程觸發。我們知道臟數據通過 page clean 線程和 lru manager 線程是在不斷寫盤的，那么在進行異常重啟的的時候我們必須要知道一個恢復的起點，但是這個起點是不能記錄在內存中必要固化到磁盤，恢復的時候讀取這個點以后的 redo 進行恢復，而 checkpoint 就是完成這個事情下面是 checkpoint 的執行流程。
正常情況下 master 會每秒進行檢查點其作用有:(參考 log_checkpoint 函數)
1、檢查是否有自上次檢查點以來的臟數據寫盤了
2、如果有則在 redo 里面會為每個修改過的文件寫入 MLOG_FILE_NAME, 完成后寫入一個總的 MLOG_CHECKPOINT(參考 fil_names_clear 函數)
MLOG_FILE_NAME 主要記錄至上次檢查點以來更改過的數據文件
MLOG_CHECKPOINT 主要記錄檢查點的 lsn
3、如果有則在 redo header 中寫入相應的檢查點信息包含(異步寫)(參考 log_group_checkpoint 函數)
Log sequence number 697794162
Log flushed up to 697794162
Pages flushed up to 697794162
Last checkpoint at 697794153
697794162-697794153 = 9 剛好是 MLOG_CHECKPOINT 的長度
oldest_lsn = log_sys- last_checkpoint_lsn + SIZE_OF_MLOG_CHECKPOINT
SIZE_OF_MLOG_CHECKPOINT=9
redo 的寫入有 6 個途徑:
1、master 線程每秒調用 棧幀(可能是 idle 可能是 active 和檢測是否需要插入緩存合并有關)
2、master 線程每秒 checkpoint 調用 (可能是 idle 可能是 active 和檢測是否需要插入緩存合并有關)
3、page clean 線程調用 棧幀 /* Force the log to the disk before writing the modified block */
4、主線程 commit 調用 棧幀
5、innodb shutdown
6、redo buffer 不足
1、master 線程調用 棧幀(可能是 idle 可能是 active 和檢測是否需要插入緩存合并有關)
#0 log_group_write_buf (group=0x33f29f8, buf=0x7fffa5b38000 \200\024 , len=512, pad_len=0, start_lsn=697764864, new_data_offset=166)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1145#1 0x0000000001a50f95 in log_write_up_to (lsn=697765068, flush_to_disk=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1493#2 0x0000000001a51163 in log_buffer_sync_in_background (flush=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1553#3 0x0000000001b84bd1 in srv_sync_log_buffer_in_background () at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0srv.cc:2312#4 0x0000000001b85666 in srv_master_do_idle_tasks () at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0srv.cc:2586#5 0x0000000001b85b6b in srv_master_thread (arg=0x0) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0srv.cc:27442、master 線程 checkpoint 調用 (可能是 idle 可能是 active 和檢測是否需要插入緩存合并有關)
#0 log_group_write_buf (group=0x33f29f8, buf=0x7fffa5a38000 \200\024\002 , len=1024, pad_len=0, start_lsn=697789952, new_data_offset=139)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1145#1 0x0000000001a50f95 in log_write_up_to (lsn=697790725, flush_to_disk=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1493#2 0x0000000001a52247 in log_checkpoint (sync=true, write_always=false) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1934#3 0x0000000001b856f2 in srv_master_do_idle_tasks () at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0srv.cc:2596#4 0x0000000001b85b6b in srv_master_thread (arg=0x0) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0srv.cc:27443、page clean 線程調用 棧幀 /* Force the log to the disk before writing the modified block */
#0 log_group_write_buf (group=0x33f29f8, buf=0x7fffa5a38000 \200\024\002 , len=13312, pad_len=1024, start_lsn=697778176, new_data_offset=468)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1145#1 0x0000000001a50f95 in log_write_up_to (lsn=697790015, flush_to_disk=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1493#2 0x0000000001c704c7 in buf_flush_write_block_low (bpage=0x7fffc0cae940, flush_type=BUF_FLUSH_LIST, sync=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:1035#3 0x0000000001c70cea in buf_flush_page (buf_pool=0x33247d8, bpage=0x7fffc0cae940, flush_type=BUF_FLUSH_LIST, sync=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:1237#4 0x0000000001c717f4 in buf_flush_try_neighbors (page_id=..., flush_type=BUF_FLUSH_LIST, n_flushed=0, n_to_flush=25)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:1466#5 0x0000000001c71b57 in buf_flush_page_and_try_neighbors (bpage=0x7fffc0cae940, flush_type=BUF_FLUSH_LIST, n_to_flush=25, count=0x7fffa02867c0)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:1558#6 0x0000000001c72862 in buf_do_flush_list_batch (buf_pool=0x33247d8, min_n=25, lsn_limit=18446744073709551615)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:1846#7 0x0000000001c72cb6 in buf_flush_batch (buf_pool=0x33247d8, flush_type=BUF_FLUSH_LIST, min_n=25, lsn_limit=18446744073709551615)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:1926#8 0x0000000001c73104 in buf_flush_do_batch (buf_pool=0x33247d8, type=BUF_FLUSH_LIST, min_n=25, lsn_limit=18446744073709551615, n_processed=0x7fffa0286938)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:2071#9 0x0000000001c734ee in buf_flush_lists (min_n=25, lsn_limit=18446744073709551615, n_processed=0x7fffa02869c8)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:2202#10 0x0000000001c76a97 in buf_flush_page_cleaner_coordinator (arg=0x0) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/buf/buf0flu.cc:33624、主線程 commit 調用 棧幀
#0 log_group_write_buf (group=0x33f29f8, buf=0x7fffa5a38000 \200\024\002 , len=2560, pad_len=0, start_lsn=697762816, new_data_offset=230)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1145#1 0x0000000001a50f95 in log_write_up_to (lsn=697765030, flush_to_disk=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1493#2 0x0000000001a51087 in log_buffer_flush_to_disk (sync=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:1524#3 0x00000000019a9157 in innobase_flush_logs (hton=0x2e9fdd0, binlog_group_flush=true)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:4407#4 0x0000000000f65893 in flush_handlerton (thd=0x0, plugin=0x7ffff03588e8, arg=0x7ffff0358944) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:2606#5 0x00000000015d7716 in plugin_foreach_with_mask (thd=0x0, func=0xf65835 flush_handlerton(THD*, plugin_ref, void*) , type=1, state_mask=4294967287,
arg=0x7ffff0358944) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_plugin.cc:2318#6 0x0000000000f658ef in ha_flush_logs (db_type=0x0, binlog_group_flush=true) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:2617#7 0x000000000185733d in MYSQL_BIN_LOG::process_flush_stage_queue (this=0x2e02c80, total_bytes_var=0x7ffff0358a88, rotate_var=0x7ffff0358a87,
out_queue_var=0x7ffff0358a78) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:8541#8 0x000000000185899f in MYSQL_BIN_LOG::ordered_commit (this=0x2e02c80, thd=0x7fff2c000b70, all=false, skip_commit=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:9189#9 0x000000000185700c in MYSQL_BIN_LOG::commit (this=0x2e02c80, thd=0x7fff2c000b70, all=false) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:8440#10 0x0000000000f63df8 in ha_commit_trans (thd=0x7fff2c000b70, all=false, ignore_global_read_lock=false)入口函數
innobase_start_or_create_for_mysql
recv_recovery_from_checkpoint_start
1、此函數需要輸入 flush 的 lsn 及臟數據寫入到的位置
這個數據從 FIL_PAGE_FILE_FLUSH_LSN 中讀取，這個值
只在 ibdata 的第一個 page 有效其他均為 0, 他的讀取來自于
函數 Datafile::validate_first_page，
其中
*flush_lsn = mach_read_from_8(
m_first_page + FIL_PAGE_FILE_FLUSH_LSN);
其寫入由函數 正常 shutdown 才會寫入, 非正常關閉不會寫入，正常運行檢查點也不會寫入
fil_write_flushed_lsn 寫入
mach_write_to_8(buf + FIL_PAGE_FILE_FLUSH_LSN, lsn);
棧幀 #0 fil_write_flushed_lsn (lsn=696973727) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/fil/fil0fil.cc:1946
#1 0x0000000001a538a7 in logs_empty_and_mark_files_at_shutdown () at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/log/log0log.cc:2464
#2 0x0000000001b915a9 in innobase_shutdown_for_mysql () at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/srv/srv0start.cc:2803
#3 0x00000000019a8ffc in innobase_end (hton=0x2e9edd0, type=HA_PANIC_CLOSE) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:4360
#4 0x0000000000f62621 in ha_finalize_handlerton (plugin=0x3015cd0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:813
#5 0x00000000015d3d25 in plugin_deinitialize (plugin=0x3015cd0, ref_check=true) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_plugin.cc:995
#6 0x00000000015d410e in reap_plugins () at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_plugin.cc:1077
#7 0x00000000015d6073 in plugin_shutdown () at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_plugin.cc:1845
#8 0x0000000000ebf7eb in clean_up (print_message=true) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/mysqld.cc:1336
#9 0x0000000000ec701b in mysqld_main (argc=98, argv=0x2e9cf08) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/mysqld.cc:5386
#10 0x0000000000ebd604 in main (argc=10, argv=0x7fffffffe458) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/main.cc:252、此函數首先建立紅黑樹用于恢復并且做 force recovery 判斷
(srv_force_recovery = SRV_FORCE_NO_LOG_REDO)
然后調用
recv_find_max_checkpoint 此函數就是找到最大的 checkpoint lsn、redo 文件, 以及 field 就是相對于一個日志而講所在的 offset set (5121 or 5123)_
讀取如下：
group- lsn = mach_read_from_8( buf + LOG_CHECKPOINT_LSN);
group- lsn_offset = mach_read_from_8( buf + LOG_CHECKPOINT_OFFSET);
checkpoint_no = mach_read_from_8( buf + LOG_CHECKPOINT_NO);3、recv_group_scan_log_recs
循環讀取 64K(RECV_SCAN_SIZE)日志到 redo buffer(log_group_read_log_seg)
recv_scan_log_recs
本函數將 64K 的 redo 通過每個 512 bytes block 大小循環加入到 (recv_sys_add_to_parsing_buf) 掃描到 parse buffer
代碼片段拷貝
ut_memcpy(recv_sys- buf + recv_sys- len,
log_block + start_offset, end_offset - start_offset);
當每次掃描了 64K*80 的日志量的時候會輸出，級 5M
ib::info() Doing recovery: scanned up to
log sequence number scanned_lsn; 并且進行分析對這加入到 parse buffer 的日志進行分析(recv_parse_log_recs) / 其中 parse buffer 為 2M(宏 RECV_PARSING_BUF_SIZE 大小)
recv_parse_log_recs 函數對每次加入 parse buffer 的 64k 進行分析主要分析是 MLOG_SINGLE_REC_FLAG 還是 MLOG_MULTI_REC_END 同時確認 MLOG_MULTI_REC_END
是否完整，完成后加入到 hash table，函數是調用 recv_parse_log_rec 進行 (type spaceid page_no data)的剝離。那么 recv_group_scan_log_recs 為第一層循環，循環掃描 64K 日志到 redo buffer
然后調用 recv_scan_log_recs 以 block 單位 (512b) 大小循環加入到 parse buffer，這是通過函數 recv_sys_add_to_parsing_buf 完成
等到 64k 加入到 parse buffer 后調用 recv_parse_log_recs 函數對每次加入 parse buffer 的 64k 進行分析，分析是循環以 record 為單位的，主要分析 MLOG_SINGLE_REC_FLAG 還是 MLOG_MULTI_REC_END，同時確保 MLOG_MULTI_REC_END 記錄是完整的。完成后 recv_parse_log_recs 函數 還要將其加入到 hash table 函數為 recv_add_to_hash_table，本函數是通過 recv_parse_log_rec 進行 (type spaceid page_no data)的剝離。
recv_apply_hashed_log_recs 最后完成分析完成后的日志應用，從 hash table 中
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