Storage engines
InnoDB
Supports transactions, row-level locking, foreign keys and encryption for tables
[ Variables | Buffer Pool | InnoDB Status ]
===================================== 2026-06-25 20:09:57 0x1fd8 INNODB MONITOR OUTPUT ===================================== Per second averages calculated from the last 9 seconds ----------------- BACKGROUND THREAD ----------------- srv_master_thread loops: 1016140 srv_active, 0 srv_shutdown, 234897 srv_idle srv_master_thread log flush and writes: 1251037 ---------- SEMAPHORES ---------- OS WAIT ARRAY INFO: reservation count 95658705 OS WAIT ARRAY INFO: signal count 14495563 RW-shared spins 273173, rounds 7589038, OS waits 233954 RW-excl spins 22738, rounds 524083, OS waits 14994 RW-sx spins 409, rounds 7394, OS waits 162 Spin rounds per wait: 27.78 RW-shared, 23.05 RW-excl, 18.08 RW-sx ------------------------ LATEST FOREIGN KEY ERROR ------------------------ 2026-06-17 04:45:37 0x3270 Transaction: TRANSACTION 17388149, 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 3317039, OS thread handle 12912, query id 288153452 122.179.243.215 AccessAdmin Updating UPDATE `marketing_ops_testing`.`department` SET `DeptCode` = 'IT02' WHERE (`DeptCode` = '1') Foreign key constraint fails for table `marketing_ops_testing`.`resourceemployment`: , CONSTRAINT `fk_DeptCode` FOREIGN KEY (`DeptCode`) REFERENCES `department` (`DeptCode`) Trying to delete or update in parent table, in index PRIMARY tuple: DATA TUPLE: 4 fields; 0: len 1; hex 31; asc 1;; 1: len 6; hex 000001095275; asc Ru;; 2: len 7; hex 17000001e7205d; asc ];; 3: len 20; hex 536f66747761726520446576656c6f706d656e74; asc Software Development;; But in child table `marketing_ops_testing`.`resourceemployment`, in index fk_DeptCode, there is a record: PHYSICAL RECORD: n_fields 2; compact format; info bits 0 0: len 1; hex 31; asc 1;; 1: len 6; hex 0000000304a4; asc ;; ------------ TRANSACTIONS ------------ Trx id counter 20526055 Purge done for trx's n:o < 20526055 undo n:o < 0 state: running History list length 6 LIST OF TRANSACTIONS FOR EACH SESSION: ---TRANSACTION 283891465900176, not started 0 lock struct(s), heap size 1128, 0 row lock(s) ---TRANSACTION 283891465904344, not started 0 lock struct(s), heap size 1128, 0 row lock(s) ---TRANSACTION 283891465921016, not started 0 lock struct(s), heap size 1128, 0 row lock(s) ---TRANSACTION 283891465908512, 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 35697937 OS file reads, 14342363 OS file writes, 8926231 OS fsyncs 61.66 reads/s, 16384 avg bytes/read, 16.78 writes/s, 10.11 fsyncs/s ------------------------------------- INSERT BUFFER AND ADAPTIVE HASH INDEX ------------------------------------- Ibuf: size 1, free list len 12, seg size 14, 209 merges merged operations: insert 116, delete mark 1289, delete 358 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) 263.64 hash searches/s, 106.21 non-hash searches/s --- LOG --- Log sequence number 13096087699 Log flushed up to 13096087679 Pages flushed up to 13096078558 Last checkpoint at 13096078558 0 pending log flushes, 0 pending chkp writes 4364961 log i/o's done, 5.11 log i/o's/second ---------------------- BUFFER POOL AND MEMORY ---------------------- Total large memory allocated 33554432 Dictionary memory allocated 678584 Buffer pool size 1003 Free buffers 730 Database pages 265 Old database pages 0 Modified db pages 19 Percent of dirty pages(LRU & free pages): 1.908 Max dirty pages percent: 75.000 Pending reads 0 Pending writes: LRU 0, flush list 0, single page 0 Pages made young 22396, not young 3062627 0.00 youngs/s, 0.00 non-youngs/s Pages read 35697651, created 140600, written 7963011 61.66 reads/s, 0.22 creates/s, 9.33 writes/s Buffer pool hit rate 981 / 1000, young-making rate 0 / 1000 not 0 / 1000 Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s LRU len: 265, unzip_LRU len: 0 I/O sum[2572]: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=4584, Main thread ID=5176, state: sleeping Number of rows inserted 1320, updated 2685067, deleted 2198, read 17639592349 0.00 inserts/s, 3.33 updates/s, 0.00 deletes/s, 22570.94 reads/s Number of system rows inserted 0, updated 0, deleted 0, read 331201 0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s ---------------------------- END OF INNODB MONITOR OUTPUT ============================