Storage engines
InnoDB
Supports transactions, row-level locking, foreign keys and encryption for tables
[
Variables
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Buffer Pool
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InnoDB Status
]
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2026-06-10 10:07:31 0x432c INNODB MONITOR OUTPUT
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Per second averages calculated from the last 37 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 50812 srv_active, 0 srv_shutdown, 5403269 srv_idle
srv_master_thread log flush and writes: 5454081
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SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 276096
OS WAIT ARRAY INFO: signal count 566361
RW-shared spins 1105383, rounds 8763603, OS waits 178910
RW-excl spins 1257473, rounds 3826835, OS waits 17107
RW-sx spins 3144, rounds 36053, OS waits 731
Spin rounds per wait: 7.93 RW-shared, 3.04 RW-excl, 11.47 RW-sx
------------------------
LATEST FOREIGN KEY ERROR
------------------------
2026-04-27 14:42:00 0x19b4 Transaction:
TRANSACTION 5704461, ACTIVE 0 sec updating or deleting
mysql tables in use 1, locked 1
4 lock struct(s), heap size 1128, 2 row lock(s), undo log entries 1
MySQL thread id 319878, OS thread handle 6580, query id 5035359 localhost 127.0.0.1 root Updating
delete from `trip_destinations` where `id` = ?
Foreign key constraint fails for table `car_program_staging`.`trip_trip_destinations`:
,
CONSTRAINT `trip_trip_destinations_ibfk_2` FOREIGN KEY (`destination_id`) REFERENCES `trip_destinations` (`id`)
Trying to delete or update in parent table, in index PRIMARY tuple:
DATA TUPLE: 8 fields;
0: len 4; hex 80000004; asc ;;
1: len 6; hex 000000570b0d; asc W ;;
2: len 7; hex 080000025b2605; asc [& ;;
3: len 6; hex 426f73746f6e; asc Boston;;
4: len 1; hex 81; asc ;;
5: len 5; hex 99b9296565; asc )ee;;
6: len 4; hex 69989119; asc i ;;
7: SQL NULL;
But in child table `car_program_staging`.`trip_trip_destinations`, in index destination_id, there is a record:
PHYSICAL RECORD: n_fields 2; compact format; info bits 0
0: len 4; hex 80000004; asc ;;
1: len 4; hex 80000002; asc ;;
------------
TRANSACTIONS
------------
Trx id counter 6109627
Purge done for trx's n:o < 6109627 undo n:o < 0 state: running but idle
History list length 0
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 283343266078864, not started
0 lock struct(s), heap size 1128, 0 row lock(s)
--------
FILE I/O
--------
I/O thread 0 state: native aio handle (insert buffer thread)
I/O thread 1 state: native aio handle (log thread)
I/O thread 2 state: native aio handle (read thread)
I/O thread 3 state: native aio handle (read thread)
I/O thread 4 state: native aio handle (read thread)
I/O thread 5 state: native aio handle (read thread)
I/O thread 6 state: native aio handle (write thread)
I/O thread 7 state: native aio handle (write thread)
I/O thread 8 state: native aio handle (write thread)
I/O thread 9 state: native aio handle (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
114026114 OS file reads, 1431810 OS file writes, 578422 OS fsyncs
2.19 reads/s, 16384 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 97, seg size 99, 3625 merges
merged operations:
insert 66457, delete mark 414, delete 69
discarded operations:
insert 0, delete mark 0, delete 0
Hash table size 4441, node heap has 1 buffer(s)
Hash table size 4441, node heap has 1 buffer(s)
Hash table size 4441, node heap has 1 buffer(s)
Hash table size 4441, node heap has 1 buffer(s)
Hash table size 4441, node heap has 1 buffer(s)
Hash table size 4441, node heap has 1 buffer(s)
Hash table size 4441, node heap has 1 buffer(s)
Hash table size 4441, node heap has 1 buffer(s)
0.00 hash searches/s, 0.00 non-hash searches/s
---
LOG
---
Log sequence number 73839316775
Log flushed up to 73839316775
Pages flushed up to 73839316775
Last checkpoint at 73839316766
0 pending log flushes, 0 pending chkp writes
336669 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total large memory allocated 33554432
Dictionary memory allocated 2822008
Buffer pool size 1003
Free buffers 0
Database pages 995
Old database pages 347
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 3153912, not young 2314065387
0.00 youngs/s, 26.62 non-youngs/s
Pages read 114025159, created 466136, written 1009644
2.19 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 920 / 1000, young-making rate 0 / 1000 not 971 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 995, unzip_LRU len: 0
I/O sum[81]: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=3528, Main thread ID=6476, state: sleeping
Number of rows inserted 3990877, updated 62523, deleted 8152, read 13605646722
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 1235912
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 204.56 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================
