Hello Everyone! I setup a classical master-slave server. Master is constantly running query like this insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); insert into t1 values(1,1,1,1,1); flush logs; insert into t1 values(1,1,1,1,1); {there are arround million querys} Then I executed Show slave status (couple of times in a second), and found Seconds_behind_master is changing arbitrarily MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Queueing master event to the relay log Master_Host: localhost Master_User: root Master_Port: 16000 Connect_Retry: 60 Master_Log_File: master-bin.014595 Read_Master_Log_Pos: 4 Relay_Log_File: slave-relay-bin.029186 Relay_Log_Pos: 3557 Relay_Master_Log_File: master-bin.014593 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 3257 Relay_Log_Space: 184375 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 148 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 Master_SSL_Crl: Master_SSL_Crlpath: Using_Gtid: Current_Pos Gtid_IO_Pos: 0-1-145942 Replicate_Do_Domain_Ids: Replicate_Ignore_Domain_Ids: Parallel_Mode: conservative SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Reading event from the relay log 1 row in set (0.01 sec) MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: localhost Master_User: root Master_Port: 16000 Connect_Retry: 60 Master_Log_File: master-bin.014632 Read_Master_Log_Pos: 3257 Relay_Log_File: slave-relay-bin.029264 Relay_Log_Pos: 1548 Relay_Master_Log_File: master-bin.014632 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 1248 Relay_Log_Space: 179996 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 Master_SSL_Crl: Master_SSL_Crlpath: Using_Gtid: Current_Pos Gtid_IO_Pos: 0-1-146322 Replicate_Do_Domain_Ids: Replicate_Ignore_Domain_Ids: Parallel_Mode: conservative SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: init 1 row in set (0.00 sec) MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Queueing master event to the relay log Master_Host: localhost Master_User: root Master_Port: 16000 Connect_Retry: 60 Master_Log_File: master-bin.014670 Read_Master_Log_Pos: 299 Relay_Log_File: slave-relay-bin.029336 Relay_Log_Pos: 3557 Relay_Master_Log_File: master-bin.014668 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 3257 Relay_Log_Space: 184569 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 150 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 Master_SSL_Crl: Master_SSL_Crlpath: Using_Gtid: Current_Pos Gtid_IO_Pos: 0-1-146692 Replicate_Do_Domain_Ids: Replicate_Ignore_Domain_Ids: Parallel_Mode: conservative SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Reading event from the relay log -- Regards Sachin Setiya Software Engineer at MariaDB