关于命令SHOW ENGINE INNODB STATUS的一些细节

其实该命令主要是在查看insertBuffer的时候用的比较多

一、\G和\g的区别

\g
　　在MySQL的sql语句后加上\g，效果等同于加上定界符，一般默认的定界符是分号;

mysql> show engine innodb status\g
+--------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Type   | Name | Status                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+--------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| InnoDB |      |
=====================================
2022-04-20 23:34:15 0x9c8 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 3 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 1 srv_active, 0 srv_shutdown, 61 srv_idle
srv_master_thread log flush and writes: 0
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 0
OS WAIT ARRAY INFO: signal count 0
RW-shared spins 0, rounds 0, OS waits 0
RW-excl spins 0, rounds 0, OS waits 0
RW-sx spins 0, rounds 0, OS waits 0
Spin rounds per wait: 0.00 RW-shared, 0.00 RW-excl, 0.00 RW-sx
------------
TRANSACTIONS
------------
Trx id counter 30473
Purge done for trx's n:o < 30470 undo n:o < 0 state: running but idle
History list length 3
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 283158070472032, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 283158070471200, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 283158070470368, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
--------
FILE I/O
--------
I/O thread 0 state: wait Windows aio (insert buffer thread)
I/O thread 1 state: wait Windows aio (log thread)
I/O thread 2 state: wait Windows aio (read thread)
I/O thread 3 state: wait Windows aio (read thread)
I/O thread 4 state: wait Windows aio (read thread)
I/O thread 5 state: wait Windows aio (read thread)
I/O thread 6 state: wait Windows aio (write thread)
I/O thread 7 state: wait Windows aio (write thread)
I/O thread 8 state: wait Windows aio (write thread)
I/O thread 9 state: wait Windows aio (write thread)
Pending normal aio reads: [0, 0, 0, 0] , aio writes: [0, 0, 0, 0] ,ibuf aio reads:, log i/o's:, sync i/o's:
Pending flushes (fsync) log: 0; buffer pool: 0
1020 OS file reads, 203 OS file writes, 38 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 0, seg size 2, 0 merges
merged operations:insert 0, delete mark 0, delete 0
discarded operations:insert 0, delete mark 0, delete 0
Hash table size 34679, node heap has 0 buffer(s)
Hash table size 34679, node heap has 0 buffer(s)
Hash table size 34679, node heap has 0 buffer(s)
Hash table size 34679, node heap has 0 buffer(s)
Hash table size 34679, node heap has 0 buffer(s)
Hash table size 34679, node heap has 0 buffer(s)
Hash table size 34679, node heap has 1 buffer(s)
Hash table size 34679, node heap has 3 buffer(s)
0.00 hash searches/s, 0.00 non-hash searches/s
---
LOG
---
Log sequence number          25880484
Log buffer assigned up to    25880484
Log buffer completed up to   25880484
Log written up to            25880484
Log flushed up to            25880484
Added dirty pages up to      25880484
Pages flushed up to          25880484
Last checkpoint at           25880484
12 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total large memory allocated 136970240
Dictionary memory allocated 373269
Buffer pool size   8192
Free buffers       7049
Database pages     1139
Old database pages 440
Modified db pages  0
Pending reads      0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 0, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 997, created 142, written 155
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 1139, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
--------------
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
0 read views open inside InnoDB
Process ID=8064, Main thread ID=00000000000036D8 , state=sleeping
Number of rows inserted 0, updated 0, deleted 0, read 0
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
Number of system rows inserted 0, updated 315, deleted 0, read 4651
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================|
+--------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

\G
在MySQL的sql语句后加上\G，表示将查询结果进行按列打印，可以使每个字段打印到单独的行。即将查到的结构旋转90度变成纵向；
（1）使用前，显示效果很差，全都是杠杠

（2）使用后，显示效果灰常好，清晰了很多，方便查询；但是记得加分号

二、打印参数详解

第一段:
*************************** 1. row ***************************
Type: InnoDB --存储引擎
Name:
Status:
=====================================
2015-04-17 10:37:02 7f1fc1fe9700 INNODB MONITOR OUTPUT --监控信息输出的时间

=====================================
Per second averages calculated from the last 14 seconds
-----------------

第二段:

BACKGROUND THREAD
-----------------
srv_master_thread loops: 0 srv_active, 0 srv_shutdown, 562 srv_idle
srv_master_thread log flush and writes: 562
----------

第三段:

SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 2
OS WAIT ARRAY INFO: signal count 2
Mutex spin waits 0, rounds 0, OS waits 0
RW-shared spins 2, rounds 60, OS waits 2
RW-excl spins 0, rounds 0, OS waits 0
Spin rounds per wait: 0.00 mutex, 30.00 RW-shared, 0.00 RW-excl
------------

第四段:

TRANSACTIONS
------------
Trx id counter 3842
Purge done for trx’s n:o < 2856 undo n:o < 0 state: running but idle
History list length 6 --记录undo日志的数量
LIST OF TRANSACTIONS FOR EACH SESSION:
—TRANSACTION 0, not started
MySQL thread id 2, OS thread handle 0x7f1fc1fe9700, query id 5 localhost root init
show engine innodb status
--------

第五段:

FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 state: waiting for completed aio requests (log thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: waiting for completed aio requests (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)
I/O thread 9 state: waiting for completed aio requests (write thread)
Pending normal aio reads: 0 [0, 0, 0, 0] , aio writes: 0 [0, 0, 0, 0] ,
ibuf aio reads: 0, log i/o’s: 0, sync i/o’s: 0
Pending flushes (fsync) log: 0; buffer pool: 0
318 OS file reads, 5 OS file writes, 5 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
-------------------------------------

buffer thread:插入缓冲线程

log thread:日志线程

read thread:读线程

write thread:写线程

第六段:

INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 0, seg size 2, 0 merges
merged operations:
insert 0, delete mark 0, delete 0
discarded operations:
insert 0, delete mark 0, delete 0
Hash table size 276671, node heap has 0 buffer(s)
0.00 hash searches/s, 0.00 non-hash searches/s
—

seg size 2:INSERT BUFFER的大小,2X16KB

ree list len 0:空闲列表的长度

Ibuf: size 1:合并记录页的数量
insert 0:INSERT BUFFER

delete mark 0:DELETE BUFFER

delete 0:PURGE BUFFER

discarded operations:Change Buffer发生merge时表已经被删除,无需再将记录合并到辅助索引中了

第七段:

LOG
—
Log sequence number 1649686 --当前的LSN号
Log flushed up to 1649686 --刷新后的LSN号
Pages flushed up to 1649686 --刷新和事物提交后的LSN号
Last checkpoint at 1649686 --写入到磁盘后的LSN号
0 pending log writes, 0 pending chkp writes
8 log i/o’s done, 0.00 log i/o’s/second
----------------------

第八段:

BUFFER POOL AND MEMORY
----------------------
Total memory allocated 137363456; in additional pool allocated 0
Dictionary memory allocated 50138
Buffer pool size 8191 --缓冲池的大小
Free buffers 8025 --剩余大小
Database pages 166 --数据库页
Old database pages 0 --旧数据库页
Modified db pages 0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 0, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 166, created 0, written 1
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 166, unzip_LRU len: 0 --LRU(缓冲池最近最少使用),一共有166个页,unzip列表中有0个页
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
--------------

第九段:
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
0 read views open inside InnoDB
Main thread process no. 27472, id 139774264338176, state: sleeping
Number of rows inserted 0, updated 0, deleted 0, read 0
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================

三、Mysql日志序列号LSN

概要：

LSN（log sequence number）：日志序列号，是一个一直递增的整形数字，在MySQL5.6.3版本后占8个字节。它表示事务写入到日志的字节总量。LSN主要用于发生crash时对数据进行recovery！每个数据页、重做日志、checkpoint都有LSN。
LSN不仅存在于重做日志中，在每个数据页头部也会有对应的LSN号。在数据页头部，LSN记录当前页最后一次修改的LSN号，用于在recovery时对比重做日志LSN号决定是否对该页进行恢复数据。checkpoint也是有LSN号记录的，LSN号串联起一个事务开始到恢复的过程。

参数说明
（以下4个LSN是递减的，即： LSN1 ≥ LSN2 ≥ LSN3 ≥ LSN4 ）

属性	说明
Log sequence number	当前系统最大的LSN号
log flushed up to	当前已经写入redo日志文件的LSN
pages flushed up to	已经将更改写入脏页的LSN号
Last checkpoint at	系统最后一次刷新buffer pool脏中页数据到磁盘的checkpoint

参考链接

https://blog.csdn.net/jasonlu888/article/details/45096885
https://blog.csdn.net/weixin_39997438/article/details/107737487
https://blog.csdn.net/sunsineq/article/details/120793940