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MySQL Group Replication extra functions and views to sys schema
USE sys;
DELIMITER $$
CREATE FUNCTION IFZERO(a INT, b INT)
RETURNS INT
DETERMINISTIC
RETURN IF(a = 0, b, a)$$
CREATE FUNCTION LOCATE2(needle TEXT(10000), haystack TEXT(10000), offset INT)
RETURNS INT
DETERMINISTIC
RETURN IFZERO(LOCATE(needle, haystack, offset), LENGTH(haystack) + 1)$$
CREATE FUNCTION GTID_NORMALIZE(g TEXT(10000))
RETURNS TEXT(10000)
DETERMINISTIC
RETURN GTID_SUBTRACT(g, '')$$
CREATE FUNCTION GTID_COUNT(gtid_set TEXT(10000))
RETURNS INT
DETERMINISTIC
BEGIN
DECLARE result BIGINT DEFAULT 0;
DECLARE colon_pos INT;
DECLARE next_dash_pos INT;
DECLARE next_colon_pos INT;
DECLARE next_comma_pos INT;
SET gtid_set = GTID_NORMALIZE(gtid_set);
SET colon_pos = LOCATE2(':', gtid_set, 1);
WHILE colon_pos != LENGTH(gtid_set) + 1 DO
SET next_dash_pos = LOCATE2('-', gtid_set, colon_pos + 1);
SET next_colon_pos = LOCATE2(':', gtid_set, colon_pos + 1);
SET next_comma_pos = LOCATE2(',', gtid_set, colon_pos + 1);
IF next_dash_pos < next_colon_pos AND next_dash_pos < next_comma_pos THEN
SET result = result +
SUBSTR(gtid_set, next_dash_pos + 1,
LEAST(next_colon_pos, next_comma_pos) - (next_dash_pos + 1)) -
SUBSTR(gtid_set, colon_pos + 1, next_dash_pos - (colon_pos + 1)) + 1;
ELSE
SET result = result + 1;
END IF;
SET colon_pos = next_colon_pos;
END WHILE;
RETURN result;
END$$
CREATE FUNCTION gr_applier_queue_length()
RETURNS INT
DETERMINISTIC
BEGIN
RETURN (SELECT sys.gtid_count( GTID_SUBTRACT( (SELECT
Received_transaction_set FROM performance_schema.replication_connection_status
WHERE Channel_name = 'group_replication_applier' ), (SELECT
@@global.GTID_EXECUTED) )));
END$$
CREATE FUNCTION gr_member_in_primary_partition()
RETURNS VARCHAR(3)
DETERMINISTIC
BEGIN
RETURN (SELECT IF( MEMBER_STATE='ONLINE' AND ((SELECT COUNT(*) FROM
performance_schema.replication_group_members WHERE MEMBER_STATE != 'ONLINE') >=
((SELECT COUNT(*) FROM performance_schema.replication_group_members)/2) = 0),
'YES', 'NO' ) FROM performance_schema.replication_group_members JOIN
performance_schema.replication_group_member_stats USING(member_id));
END$$
CREATE VIEW gr_member_routing_candidate_status AS SELECT
sys.gr_member_in_primary_partition() as viable_candidate,
IF( (SELECT (SELECT GROUP_CONCAT(variable_value) FROM
performance_schema.global_variables WHERE variable_name IN ('read_only',
'super_read_only')) != 'OFF,OFF'), 'YES', 'NO') as read_only,
sys.gr_applier_queue_length() as transactions_behind, Count_Transactions_in_queue as 'transactions_to_cert' from performance_schema.replication_group_member_stats;$$
DELIMITER ;
@dungdm93

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dungdm93 Jul 14, 2018

Hello @lefred

I have a MySQL InnoDB cluster with 3 nodes:

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| group_replication_applier | 76491f7d-8743-11e8-9f3a-42010a940005 | mysql-3     |        3306 | ONLINE       | SECONDARY   | 8.0.11         |
| group_replication_applier | 76b64835-8743-11e8-aa21-42010a940004 | mysql-2     |        3306 | ONLINE       | SECONDARY   | 8.0.11         |
| group_replication_applier | 7976f7e0-8743-11e8-96b1-42010a940002 | mysql-1     |        3306 | ONLINE       | PRIMARY     | 8.0.11         |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
3 rows in set (0.00 sec)

And when runing gr_member_in_primary_partition, I got below error:

mysql> SELECT gr_member_in_primary_partition();
ERROR 1242 (21000): Subquery returns more than 1 row

dungdm93 commented Jul 14, 2018

Hello @lefred

I have a MySQL InnoDB cluster with 3 nodes:

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| group_replication_applier | 76491f7d-8743-11e8-9f3a-42010a940005 | mysql-3     |        3306 | ONLINE       | SECONDARY   | 8.0.11         |
| group_replication_applier | 76b64835-8743-11e8-aa21-42010a940004 | mysql-2     |        3306 | ONLINE       | SECONDARY   | 8.0.11         |
| group_replication_applier | 7976f7e0-8743-11e8-96b1-42010a940002 | mysql-1     |        3306 | ONLINE       | PRIMARY     | 8.0.11         |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
3 rows in set (0.00 sec)

And when runing gr_member_in_primary_partition, I got below error:

mysql> SELECT gr_member_in_primary_partition();
ERROR 1242 (21000): Subquery returns more than 1 row
@prowebuk

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prowebuk Aug 5, 2018

Hi @lefred

I'm also seeing the same error as @dungdm93

SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| group_replication_applier | 08944f18-504f-11e8-bcfa-12262f7a10f8 | re-fn-sql-2 | 3306 | RECOVERING | SECONDARY | 8.0.11 |
| group_replication_applier | 2f9abf14-5038-11e8-8a6a-8a384fff7eff | re-fn-sql-3 | 3306 | ONLINE | SECONDARY | 8.0.11 |
| group_replication_applier | df64619a-5037-11e8-ba35-2a9e5f2f8438 | re-fn-sql-1 | 3306 | ONLINE | PRIMARY | 8.0.11 |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+

mysql> select * from gr_member_routing_candidate_status;
1242 - Subquery returns more than 1 row

Grateful for any assistance

prowebuk commented Aug 5, 2018

Hi @lefred

I'm also seeing the same error as @dungdm93

SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+
| group_replication_applier | 08944f18-504f-11e8-bcfa-12262f7a10f8 | re-fn-sql-2 | 3306 | RECOVERING | SECONDARY | 8.0.11 |
| group_replication_applier | 2f9abf14-5038-11e8-8a6a-8a384fff7eff | re-fn-sql-3 | 3306 | ONLINE | SECONDARY | 8.0.11 |
| group_replication_applier | df64619a-5037-11e8-ba35-2a9e5f2f8438 | re-fn-sql-1 | 3306 | ONLINE | PRIMARY | 8.0.11 |
+---------------------------+--------------------------------------+-------------+-------------+--------------+-------------+----------------+

mysql> select * from gr_member_routing_candidate_status;
1242 - Subquery returns more than 1 row

Grateful for any assistance

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