SHOW ENGINE INNODB STATUS

SHOW ENGINE INNODB STATUS is a specific form of the SHOW ENGINE statement that displays the InnoDB Monitor output, which is extensive InnoDB information which can be useful in diagnosing problems.

The following sections are displayed

  • Status: Shows the timestamp, monitor name and the number of seconds, or the elapsed time between the current time and the time the InnoDB Monitor output was last displayed. The per-second averages are based upon this time.
  • BACKGROUND THREAD: srv_master_thread lines show work performed by the main background thread.
  • SEMAPHORES: Threads waiting for a semaphore and stats on how the number of times threads have needed a spin or a wait on a mutex or rw-lock semaphore. If this number of threads is large, there may be I/O or contention issues. Reducing the size of the innodb_thread_concurrency system variable may help if contention is related to thread scheduling. Spin rounds per wait shows the number of spinlock rounds per OS wait for a mutex.
  • LATEST FOREIGN KEY ERROR: Only shown if there has been a foreign key constraint error, it displays the failed statement and information about the constraint and the related tables.
  • LATEST DETECTED DEADLOCK: Only shown if there has been a deadlock, it displays the transactions involved in the deadlock and the statements being executed, held and required locked and the transaction rolled back to.
  • TRANSACTIONS: The output of this section can help identify lock contention, as well as reasons for the deadlocks.
  • FILE I/O: InnoDB thread information as well as pending I/O operations and I/O performance statistics.
  • INSERT BUFFER AND ADAPTIVE HASH INDEX: InnoDB insert buffer and adaptive hash index status information, including the number of each type of operation performed, and adaptive hash index performance.
  • LOG: InnoDB log information, including current log sequence number, how far the log has been flushed to disk, the position at which InnoDB last took a checkpoint, pending writes and write performance statistics.
  • BUFFER POOL AND MEMORY: Information on buffer pool pages read and written, which allows you to see the number of data file I/O operations performed by your queries. See XtraDB/InnoDB Buffer Pool for more. Similar information is also available from the INFORMATION_SCHEMA.INNODB_BUFFER_POOL_STATS table.
  • ROW OPERATIONS:Information about the main thread, including the number and performance rate for each type of row operation.

If the innodb_status_output_locks system variable is set to 1, extended lock information will be displayed.

Example output:

=====================================
2016-09-12 04:42:15 7f226145fb00 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 29 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 0 srv_active, 0 srv_shutdown, 527 srv_idle
srv_master_thread log flush and writes: 527
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 4
OS WAIT ARRAY INFO: signal count 4
Mutex spin waits 2, rounds 60, OS waits 2
RW-shared spins 2, rounds 60, OS waits 2
RW-excl spins 0, rounds 0, OS waits 0
Spin rounds per wait: 30.00 mutex, 30.00 RW-shared, 0.00 RW-excl
------------
TRANSACTIONS
------------
Trx id counter 2308
Purge done for trx's n:o < 0 undo n:o < 0 state: running but idle
History list length 0
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 0, not started
MySQL thread id 3, OS thread handle 0x7f226145fb00, query id 4 localhost root init
SHOW ENGINE INNODB STATUS
--------
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
172 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
-------------------------------------
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
0.00 hash searches/s, 0.00 non-hash searches/s
---
LOG
---
Log sequence number 1616829
Log flushed up to   1616829
Pages flushed up to 1616829
Last checkpoint at  1616829
Max checkpoint age    80826164
Checkpoint age target 78300347
Modified age          0
Checkpoint age        0
0 pending log writes, 0 pending chkp writes
8 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total memory allocated 140771328; in additional pool allocated 0
Total memory allocated by read views 88
Internal hash tables (constant factor + variable factor)
    Adaptive hash index 2217568 	(2213368 + 4200)
    Page hash           139112 (buffer pool 0 only)
    Dictionary cache    630703 	(554768 + 75935)
    File system         817648 	(812272 + 5376)
    Lock system         333232 	(332872 + 360)
    Recovery system     0 	(0 + 0)
Dictionary memory allocated 75935
Buffer pool size        8191
Buffer pool size, bytes 134201344
Free buffers            8037
Database pages          154
Old database pages      0
Modified db pages       0
Percent of dirty pages(LRU & free pages): 0.000
Max dirty pages percent: 75.000
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 154, 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: 154, 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
0 RW transactions active inside InnoDB
0 RO transactions active inside InnoDB
0 out of 1000 descriptors used
Main thread process no. 3337, id 139784957703936, 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 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
============================

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