如果你是后台开发者，InnoDB的小秘密，你应该知道

mysql> SHOW ENGINE INNODB STATUS\G;
*************************** 1. row ***************************
  Type: InnoDB
  Name:
Status:
=====================================
2019-04-15 08:48:01 0xf44 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 43 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 6 srv_active, 0 srv_shutdown, 4557 srv_idle
srv_master_thread log flush and writes: 0
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 7
OS WAIT ARRAY INFO: signal count 5
RW-shared spins 0, rounds 0, OS waits 0
RW-excl spins 3, rounds 106, OS waits 3
RW-sx spins 0, rounds 0, OS waits 0
Spin rounds per wait: 0.00 RW-shared, 35.33 RW-excl, 0.00 RW-sx
------------
TRANSACTIONS
------------
Trx id counter 2592
Purge done for trx‘s n:o < 2591 undo n:o < 0 state: running but idle
History list length 9
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 281475306751792, 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
854 OS file reads, 381 OS file writes, 100 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 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 1 buffer(s)
Hash table size 2267, node heap has 3 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
0.00 hash searches/s, 0.00 non-hash searches/s
---
LOG
---
Log sequence number          19117710
Log buffer assigned up to    19117710
Log buffer completed up to   19117710
Log written up to            19117710
Log flushed up to            19117710
Added dirty pages up to      19117710
Pages flushed up to          19117710
Last checkpoint at           19117710
64 log i/o‘s done, 0.00 log i/o‘s/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total large memory allocated 8585216
Dictionary memory allocated 396496
Buffer pool size   512
Free buffers       252
Database pages     256
Old database pages 0
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 831, created 154, written 265
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: 256, 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=1440, Main thread ID=000000000000093C , state=sleeping
Number of rows inserted 24, updated 335, deleted 6, read 4975
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)

ERROR:
No query specified

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