Due to the failure of foreign key detection, Galera slave node killed himself.

[ERROR] Slave SQL: Could not execute Delete_rows_v1 event on table aaa.p; Cannot delete or update a parent row: a foreign key constraint fails (`aaa`.`f`, CONSTRAINT `f_ibfk_1` FOREIGN KEY (`f_id`) REFERENCES `p` (`id`)), Error_code: 1451; handler error HA_ERR_ROW_IS_REFERENCED; the event's master log FIRST, end_log_pos 108, Internal MariaDB error code: 1451

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: RBR event 3 Delete_rows_v1 apply warning: 152, 128

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: Failed to apply app buffer: seqno: 128, status: 1

         at galera/src/trx_handle.cpp:apply():351

CREATE TABLE `p` (

  `id` int(11) NOT NULL,

  `a` varchar(33) COLLATE utf8mb4_unicode_ci DEFAULT NULL,

  PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci ;

CREATE TABLE `f` (

  `id` int(11) NOT NULL,

  `f_id` int(11) DEFAULT NULL,

  KEY `f_id` (`f_id`),

  CONSTRAINT `f_ibfk_1` FOREIGN KEY (`f_id`) REFERENCES `p` (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci ;

insert into p select 1,'aaa';

insert into f select 1,1;

#Repeatedly execute the following SQL until you generate thousands of data

insert into f select a.id + b.a,a.f_id from f a join (select max(id) as a from f b) b on 1=1;

select count(*) from f;

+----------+

| count(*) |

+----------+

|   131072 |

+----------+

#Slave node, no matter wsrep_slave_fk_checks is on or off.

show variables like 'wsrep_slave_fk_checks';

+-----------------------+-------+

| Variable_name         | Value |

+-----------------------+-------+

| wsrep_slave_fk_checks | ON    |

+-----------------------+-------+

#Master (Write) node

delete from f;delete from p;

#Slave node down and got errors

2018-03-16 14:33:39 140457990018816 [ERROR] Slave SQL: Could not execute Delete_rows_v1 event on table aaa.p; Cannot delete or update a parent row: a foreign key constraint fails (`aaa`.`f`, CONSTRAINT `f_ibfk_1` FOREIGN KEY (`f_id`) REFERENCES `p` (`id`)), Error_code: 1451; handler error HA_ERR_ROW_IS_REFERENCED; the event's master log FIRST, end_log_pos 108, Internal MariaDB error code: 1451

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: RBR event 3 Delete_rows_v1 apply warning: 152, 128

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: Failed to apply app buffer: seqno: 128, status: 1

         at galera/src/trx_handle.cpp:apply():351

Retrying 2th time

2018-03-16 14:33:39 140457990018816 [ERROR] Slave SQL: Could not execute Delete_rows_v1 event on table aaa.p; Cannot delete or update a parent row: a foreign key constraint fails (`aaa`.`f`, CONSTRAINT `f_ibfk_1` FOREIGN KEY (`f_id`) REFERENCES `p` (`id`)), Error_code: 1451; handler error HA_ERR_ROW_IS_REFERENCED; the event's master log FIRST, end_log_pos 108, Internal MariaDB error code: 1451

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: RBR event 3 Delete_rows_v1 apply warning: 152, 128

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: Failed to apply app buffer: seqno: 128, status: 1

         at galera/src/trx_handle.cpp:apply():351

Retrying 3th time

2018-03-16 14:33:39 140457990018816 [ERROR] Slave SQL: Could not execute Delete_rows_v1 event on table aaa.p; Cannot delete or update a parent row: a foreign key constraint fails (`aaa`.`f`, CONSTRAINT `f_ibfk_1` FOREIGN KEY (`f_id`) REFERENCES `p` (`id`)), Error_code: 1451; handler error HA_ERR_ROW_IS_REFERENCED; the event's master log FIRST, end_log_pos 108, Internal MariaDB error code: 1451

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: RBR event 3 Delete_rows_v1 apply warning: 152, 128

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: Failed to apply app buffer: seqno: 128, status: 1

         at galera/src/trx_handle.cpp:apply():351

Retrying 4th time

2018-03-16 14:33:39 140457990018816 [ERROR] Slave SQL: Could not execute Delete_rows_v1 event on table aaa.p; Cannot delete or update a parent row: a foreign key constraint fails (`aaa`.`f`, CONSTRAINT `f_ibfk_1` FOREIGN KEY (`f_id`) REFERENCES `p` (`id`)), Error_code: 1451; handler error HA_ERR_ROW_IS_REFERENCED; the event's master log FIRST, end_log_pos 108, Internal MariaDB error code: 1451

2018-03-16 14:33:39 140457990018816 [Warning] WSREP: RBR event 3 Delete_rows_v1 apply warning: 152, 128

2018-03-16 14:33:39 140457990018816 [ERROR] WSREP: Failed to apply trx: source: 849e805c-1dd2-11e8-aa79-eb31f2b81368 version: 3 local: 0 state: APPLYING flags: 1 conn_id: 87 trx_id: 12277 seqnos (l: 33, g: 128, s: 127, d: 126, ts: 1358419270394303)

2018-03-16 14:33:39 140457990018816 [ERROR] WSREP: Failed to apply trx 128 4 times

2018-03-16 14:33:39 140457990018816 [ERROR] WSREP: Node consistency compromised, aborting...

#Slave processlist

#Write set 127 is "delete from f;"

#Write set 128 is "delete from p;"

#Slave concurrently apply the two sql

 !image-2018-03-21-10-45-36-084.png|thumbnail!