SHOW ENGINE INNODB STATUS

View extensive status information for the InnoDB engine. This statement displays details on deadlocks, buffer pool usage, and I/O activity.

Syntax

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 (old name for the change 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 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:

===================================== 2019-09-06 12:44:13 0x7f93cc236700 INNODB MONITOR OUTPUT ===================================== Per second averages calculated from the last 4 seconds ----------------- BACKGROUND THREAD ----------------- srv_master_thread loops: 2 srv_active, 0 srv_shutdown, 83698 srv_idle srv_master_thread log flush and writes: 83682 ---------- SEMAPHORES ---------- OS WAIT ARRAY INFO: reservation count 15 OS WAIT ARRAY INFO: signal count 8 RW-shared spins 0, rounds 20, OS waits 7 RW-excl spins 0, rounds 0, OS waits 0 RW-sx spins 0, rounds 0, OS waits 0 Spin rounds per wait: 20.00 RW-shared, 0.00 RW-excl, 0.00 RW-sx ------------ TRANSACTIONS ------------ Trx id counter 236 Purge done for trx's n:o < 236 undo n:o < 0 state: running History list length 22 LIST OF TRANSACTIONS FOR EACH SESSION: ---TRANSACTION 421747401994584, not started 0 lock struct(s), heap size 1136, 0 row lock(s) ---TRANSACTION 421747401990328, not started 0 lock struct(s), heap size 1136, 0 row lock(s) -------- 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] , aio writes: [0, 0, 0, 0] ,  ibuf aio reads:, log i/o's:, sync i/o's: Pending flushes (fsync) log: 0; buffer pool: 0 286 OS file reads, 171 OS file writes, 22 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 0 buffer(s) Hash table size 34679, node heap has 0 buffer(s) 0.00 hash searches/s, 0.00 non-hash searches/s --- LOG --- Log sequence number 445926 Log flushed up to 445926 Pages flushed up to 445926 Last checkpoint at 445917 0 pending log flushes, 0 pending chkp writes 18 log i/o's done, 0.00 log i/o's/second ---------------------- BUFFER POOL AND MEMORY ---------------------- Total large memory allocated 167772160 Dictionary memory allocated 50768 Buffer pool size 8012 Free buffers 7611 Database pages 401 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 264, created 137, written 156 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: 401, 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=4267, Main thread ID=140272021272320, state: sleeping Number of rows inserted 1, updated 0, deleted 0, read 1 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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