I was given two fairly new servers and setup master and slave running MySQL 5.7.17, Linux RedHat 6. Both servers are using binlog_format=STATEMENT.
I can't understand why my slave is processing so slowly though I know the bottleneck with the single thread process from my slave. I believe our master server does not contain a lot of parallel queries though.
Slave > show processlist;
Id: 22593
User: system user
Host:
db: Database1
Command: Connect
Time: 2364340
State: updating
Info: update TableA set colA.....
This transaction is processing like 0.5s for every update. The total rows count for the table is just under 100,000 rows. I am not sure if my expectation is right that it should be fast.
I turn on general_log to capture for several seconds and switch off back.
Excerpt:
2016-12-28T10:26:53.937824Z 22093 Query COMMIT /* implicit, from Xid_log_event */
2016-12-28T10:26:53.938293Z 22093 Query BEGIN
2016-12-28T10:26:54.404481Z 22093 Query update Table10 set COLA='XXX', COLB='XXXX', COLC='', COLD='', COLE='XXXX', COLF='XXXX' where COLB='YY' and COLF='ZZZZZZ'
2016-12-28T10:26:54.404576Z 22093 Query COMMIT /* implicit, from Xid_log_event */
slave > show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: masterA
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: masterA-bin.000117
Read_Master_Log_Pos: 818913948
Relay_Log_File: slaveB-relay-bin.001168
Relay_Log_Pos: 42738489
Relay_Master_Log_File: masterA-bin.000116
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: 42738264
Relay_Log_Space: 1939474024
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: 60598
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: 10
Master_UUID: XXXXXXXXXXXXXXXXXXXXXXXXXXXxx
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: updating
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
masterA> show master status\G;
*************************** 1. row ***************************
File: masterA-bin.000117
Position: 818913948
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)
Based on the readings, my I/O thread is doing not too bad. Catching up with master log at masterA-bin.000117. But the SQL thread is lagging behind. masterA-bin.000116. Relay_Log_Pos: 42738489
SQL thread is replaying at slaveB-relay-bin.001168. But when I check my OS directory /log, I can see slaveB-relay-bin.001341 as the latest generated.
The slave is continuously lagging behind master. I have set
- sync_binlog=1
- Comment log-slave-updates
- innodb_flush_log_at_trx_commit=2
But it helps a little only, reducing probably 1-2 seconds of lag.
I am using STATEMENT binlog, will it matters if some tables does not have primary/unique key?
I'd to know if there are other means to speed up the replication without multithreaded slave?