MySQL 死锁套路：再来看一例走不同索引更新的例子

CREATE TABLE `t3` (  `id` int(11) NOT NULL AUTO_INCREMENT,  `a` varchar(5) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',  `b` varchar(5) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',  PRIMARY KEY (`id`),UNIQUE KEY `uk_a` (`a`), KEY `idx_b` (`b`) )

t1update t3 set b = '' where a = "1";
t2update t3 set b = '' where b = "2";

------------------------LATEST DETECTED DEADLOCK------------------------181102 12:45:05*** (1) TRANSACTION:TRANSACTION 50AF, ACTIVE 0 sec starting index readmysql tables in use 1, locked 1LOCK WAIT 3 lock struct(s), heap size 376, 2 row lock(s)MySQL thread id 34, OS thread handle 0x70000d842000, query id 549 localhost 127.0.0.1 root Searching rows for updateupdate t3 set b = '' where b = "2"*** (1) WAITING FOR THIS LOCK TO BE GRANTED:RECORD LOCKS space id 67 page no 3 n bits 72 index `PRIMARY` of table `d1`.`t3` trx id 50AF lock_mode X locks rec but not gap waitingRecord lock, heap no 2 PHYSICAL RECORD: n_fields 5; compact format; info bits 0 0: len 4; hex 80000001; asc     ;; 1: len 6; hex 0000000050ae; asc     P ;; 2: len 7; hex 03000001341003; asc     4  ;; 3: len 1; hex 31; asc 1;; 4: len 0; hex ; asc ;;
*** (2) TRANSACTION:TRANSACTION 50AE, ACTIVE 0 sec updating or deletingmysql tables in use 1, locked 14 lock struct(s), heap size 1248, 3 row lock(s), undo log entries 1MySQL thread id 35, OS thread handle 0x70000d885000, query id 548 localhost 127.0.0.1 root Updatingupdate t3 set b = '' where a = "1"*** (2) HOLDS THE LOCK(S):RECORD LOCKS space id 67 page no 3 n bits 72 index `PRIMARY` of table `d1`.`t3` trx id 50AE lock_mode X locks rec but not gapRecord lock, heap no 2 PHYSICAL RECORD: n_fields 5; compact format; info bits 0 0: len 4; hex 80000001; asc     ;; 1: len 6; hex 0000000050ae; asc     P ;; 2: len 7; hex 03000001341003; asc     4  ;; 3: len 1; hex 31; asc 1;; 4: len 0; hex ; asc ;;
*** (2) WAITING FOR THIS LOCK TO BE GRANTED:RECORD LOCKS space id 67 page no 5 n bits 72 index `idx_b` of table `d1`.`t3` trx id 50AE lock_mode X locks rec but not gap waitingRecord lock, heap no 2 PHYSICAL RECORD: n_fields 2; compact format; info bits 0 0: len 1; hex 32; asc 2;; 1: len 4; hex 80000001; asc     ;;
*** WE ROLL BACK TRANSACTION (1)