#==== EXAMPLE FOR THE codfw -> eqiad SWITCH ====
Executing commands ('mysql --skip-ssl --skip-column-names --batch -e "SELECT @@GLOBAL.gtid_binlog_pos"',) on 1 hosts: db2034.ts FROM heartbeat.heartbeat WHERE datacenter = \'codfw.wmnet\' and shard
----- OUTPUT of 'mysql --skip-ssl...gtid_binlog_pos"' -----= \'s1\' ORDER BY ts DESC LIMIT 1"',) on 1 hosts: db2048.codfw.wmnet
171966572-171966572-297840043,171974681-171974681-198565537,180355159-180355159-17196909,180363268-180363268-40608909----- OUTPUT of 'mysql --skip-ssl...ts DESC LIMIT 1"' -----
2018-09-06T16:42:37.001790
================
PASS: |####################################################################################################| 100% (1/1) [00:00<00:00, 3.0206hosts/s]
FAIL: | | 0% (0/1) [00:00<?, ?hosts/s]
100.0% (1/1) success ratio (>= 100.0% threshold) for command: 'mysql --skip-ssl...gtid_binlog_pos"'ts DESC LIMIT 1"'.
100.0% (1/1) success ratio (>= 100.0% threshold) of nodes successfully executed all commands.
Executing commands ('mysql --skip-ssl --skip-column-names --batch -e "SELECT MASTER_GTID_WAIT(\'171966572-171966572-297840043,171974681-17197468ts FROM heartbeat.heartbeat WHERE datacenter = \'codfw\' and shard
1-198565537,180355159-180355159-17196909,180363268-180363268-40608909\', 30)= \'s1\' ORDER BY ts DESC LIMIT 1"',) on 1 hosts: db10697.eqiad.wmnet
----- OUTPUT of 'mysql --skip-ssl...-40608909', 30)ts DESC LIMIT 1"' -----
2018-09-06T16:42:50.001530
================
PASS: |####################################################################################################| 100% (1/1) [00:00<00:00, 1.3743hosts/s]
FAIL: | | 0% (0/1) [00:00<?, ?hosts/s]
100.0% (1/1) success ratio (>= 100.0% threshold) for command: 'mysql --skip-ssl...-40608909', 30)"'ts DESC LIMIT 1"'.
100.0% (1/1) success ratio (>= 100.0% threshold) of nodes successfully executed all commands.
And the later check passed without retries. This because we do first gather all the positions from dc_from and then check dc_to, so some time passes between one and the other.