Pre-General Availability Draft: 2017-05-26
SHOW SLAVE STATUS [FOR CHANNEL
SHOW SLAVE STATUS is nonblocking. When run
SHOW SLAVE STATUS returns without waiting for
STOP SLAVE to finish shutting down the slave
SQL thread or slave I/O thread (or both). This permits use in
monitoring and other applications where getting an immediate
SHOW SLAVE STATUS more
important than ensuring that it returned the latest data.
If you issue this statement using the mysql
client, you can use a
\G statement terminator
rather than a semicolon to obtain a more readable vertical
SHOW SLAVE STATUS\G*************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: localhost Master_User: root Master_Port: 13000 Connect_Retry: 60 Master_Log_File: master-bin.000002 Read_Master_Log_Pos: 1307 Relay_Log_File: slave-relay-bin.000003 Relay_Log_Pos: 1508 Relay_Master_Log_File: master-bin.000002 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: 1307 Relay_Log_Space: 1858 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_UUID: 3e11fa47-71ca-11e1-9e33-c80aa9429562 Master_Info_File: /var/mysqld.2/data/master.info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it Master_Retry_Count: 10 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: 3e11fa47-71ca-11e1-9e33-c80aa9429562:1-5 Executed_Gtid_Set: 3e11fa47-71ca-11e1-9e33-c80aa9429562:1-5 Auto_Position: 1 Replicate_Rewrite_DB: Channel_name: 1 row in set (0.00 sec)
The Performance Schema provides tables that expose replication
information. This is similar to the information available from
SHOW SLAVE STATUS statement,
but represented in table form. For details, see
Section 24.11.11, “Performance Schema Replication Tables”.
A copy of the
Statefield of the
SHOW PROCESSLISToutput for the slave I/O thread. This tells you what the thread is doing: trying to connect to the master, waiting for events from the master, reconnecting to the master, and so on. For a listing of possible states, see Section 9.14.5, “Replication Slave I/O Thread States”.
The master host that the slave is connected to.
The user name of the account used to connect to the master.
The port used to connect to the master.
The number of seconds between connect retries (default 60). This can be set with the
CHANGE MASTER TOstatement.
The name of the master binary log file from which the I/O thread is currently reading.
The position in the current master binary log file up to which the I/O thread has read.
The name of the relay log file from which the SQL thread is currently reading and executing.
The position in the current relay log file up to which the SQL thread has read and executed.
The name of the master binary log file containing the most recent event executed by the SQL thread.
Whether the I/O thread is started and has connected successfully to the master. Internally, the state of this thread is represented by one of the following three values:
MYSQL_SLAVE_NOT_RUN. The slave I/O thread is not running. For this state,
MYSQL_SLAVE_RUN_NOT_CONNECT. The slave I/O thread is running, but is not connected to a replication master. For this state,
Slave_IO_Runningdepends on the server version as shown in the following table.
4.1 (4.1.13 and earlier); 5.0 (5.0.11 and earlier)
4.1 (4.1.14 and later); 5.0 (5.0.12 and later)
5.1 (5.1.45 and earlier)
5.1 (5.1.46 and later); 5.5; 5.6
MYSQL_SLAVE_RUN_CONNECT. The slave I/O thread is running, and is connected to a replication master. For this state,
The value of the
Slave_runningsystem status variable corresponds with this value.
Whether the SQL thread is started.
These columns are aliases for
When the slave SQL thread receives an error, it reports the error first, then stops the SQL thread. This means that there is a small window of time during which
SHOW SLAVE STATUSshows a nonzero value for
The current value of the
sql_slave_skip_countersystem variable. See Section 188.8.131.52, “SET GLOBAL sql_slave_skip_counter Syntax”.
The position in the current master binary log file to which the SQL thread has read and executed, marking the start of the next transaction or event to be processed. You can use this value with the
CHANGE MASTER TOstatement's
MASTER_LOG_POSoption when starting a new slave from an existing slave, so that the new slave reads from this point. The coordinates given by (
Exec_Master_Log_Pos) in the master's binary log correspond to the coordinates given by (
Relay_Log_Pos) in the relay log.
Inconsistencies in the sequence of transactions from the relay log which have been executed can cause this value to be a “low-water mark”. In other words, transactions appearing before the position are guaranteed to have committed, but transactions after the position may have committed or not. If these gaps need to be corrected, use
START SLAVE UNTIL SQL_AFTER_MTS_GAPS. See Section 184.108.40.206, “Replication and Transaction Inconsistencies” for more information.
The total combined size of all existing relay log files.
The values specified in the
UNTILclause of the
Until_Conditionhas these values:
UNTILclause was specified
Masterif the slave is reading until a given position in the master's binary log
Relayif the slave is reading until a given position in its relay log
SQL_BEFORE_GTIDSif the slave SQL thread is processing transactions until it has reached the first transaction whose GTID is listed in the
SQL_AFTER_GTIDSif the slave threads are processing all transactions until the last transaction in the
gtid_sethas been processed by both threads.
SQL_AFTER_MTS_GAPSif a multi-threaded slave's SQL threads are running until no more gaps are found in the relay log.
Until_Log_Posindicate the log file name and position that define the coordinates at which the SQL thread stops executing.
For more information on
UNTILclauses, see Section 220.127.116.11, “START SLAVE Syntax”.
These fields show the SSL parameters used by the slave to connect to the master, if any.
Master_SSL_Allowedhas these values:
Yesif an SSL connection to the master is permitted
Noif an SSL connection to the master is not permitted
Ignoredif an SSL connection is permitted but the slave server does not have SSL support enabled
The values of the other SSL-related fields correspond to the values of the
MASTER_SSL_VERIFY_SERVER_CERToptions to the
CHANGE MASTER TOstatement. See Section 18.104.22.168, “CHANGE MASTER TO Syntax”.
This field is an indication of how “late” the slave is:
When the slave is actively processing updates, this field shows the difference between the current timestamp on the slave and the original timestamp logged on the master for the event currently being processed on the slave.
When no event is currently being processed on the slave, this value is 0.
In essence, this field measures the time difference in seconds between the slave SQL thread and the slave I/O thread. If the network connection between master and slave is fast, the slave I/O thread is very close to the master, so this field is a good approximation of how late the slave SQL thread is compared to the master. If the network is slow, this is not a good approximation; the slave SQL thread may quite often be caught up with the slow-reading slave I/O thread, so
Seconds_Behind_Masteroften shows a value of 0, even if the I/O thread is late compared to the master. In other words, this column is useful only for fast networks.
This time difference computation works even if the master and slave do not have identical clock times, provided that the difference, computed when the slave I/O thread starts, remains constant from then on. Any changes—including NTP updates—can lead to clock skews that can make calculation of
In MySQL 8.0, this field is
NULL(undefined or unknown) if the slave SQL thread is not running, or if the SQL thread has consumed all of the relay log and the slave I/O thread is not running. (In older versions of MySQL, this field was
NULLif the slave SQL thread or the slave I/O thread was not running or was not connected to the master.) If the I/O thread is running but the relay log is exhausted,
Seconds_Behind_Masteris set to 0.
The value of
Seconds_Behind_Masteris based on the timestamps stored in events, which are preserved through replication. This means that if a master M1 is itself a slave of M0, any event from M1's binary log that originates from M0's binary log has M0's timestamp for that event. This enables MySQL to replicate
TIMESTAMPsuccessfully. However, the problem for
Seconds_Behind_Masteris that if M1 also receives direct updates from clients, the
Seconds_Behind_Mastervalue randomly fluctuates because sometimes the last event from M1 originates from M0 and sometimes is the result of a direct update on M1.
When using a multi-threaded slave, you should keep in mind that this value is based on
Exec_Master_Log_Pos, and so may not reflect the position of the most recently committed transaction.
The error number and error message of the most recent error that caused the I/O thread to stop. An error number of 0 and message of the empty string mean “no error.” If the
Last_IO_Errorvalue is not empty, the error values also appear in the slave's error log.
I/O error information includes a timestamp showing when the most recent I/O thread error occurred. This timestamp uses the format
YYMMDD HH:MM:SS, and appears in the
The error number and error message of the most recent error that caused the SQL thread to stop. An error number of 0 and message of the empty string mean “no error.” If the
Last_SQL_Errorvalue is not empty, the error values also appear in the slave's error log.
If the slave is multi-threaded, the SQL thread is the coordinator for worker threads. In this case, the
Last_SQL_Errorfield shows exactly what the
Last_Error_Messagecolumn in the Performance Schema
replication_applier_status_by_coordinatortable shows. The field value is modified to suggest that there may be more failures in the other worker threads which can be seen in the
replication_applier_status_by_workertable that shows each worker thread's status. If that table is not available, the slave error log can be used. The log or the
replication_applier_status_by_workertable should also be used to learn more about the failure shown by
SHOW SLAVE STATUSor the coordinator table.
SQL error information includes a timestamp showing when the most recent SQL thread error occurred. This timestamp uses the format
YYMMDD HH:MM:SS, and appears in the
In MySQL 8.0, all error codes and messages displayed in the
Last_SQL_Errorcolumns correspond to error values listed in Section B.3, “Server Error Codes and Messages”. This was not always true in previous versions. (Bug #11760365, Bug #52768)
In MySQL 8.0, you set a slave to ignore events from 0 or more masters using the
IGNORE_SERVER_IDSoption of the
CHANGE MASTER TOstatement. By default this is blank, and is usually modified only when using a circular or other multi-master replication setup. The message shown for
Replicate_Ignore_Server_Idswhen not blank consists of a comma-delimited list of one or more numbers, indicating the server IDs to be ignored. For example:
Replicate_Ignore_Server_Ids: 2, 6, 9Note
Ignored_server_idsalso shows the server IDs to be ignored, but is a space-delimited list, which is preceded by the total number of server IDs to be ignored. For example, if a
CHANGE MASTER TOstatement containing the
IGNORE_SERVER_IDS = (2,6,9)option has been issued to tell a slave to ignore masters having the server ID 2, 6, or 9, that information appears as shown here:
Ignored_server_ids: 3, 2, 6, 9
The first number (in this case
3) shows the number of server IDs being ignored.
Replicate_Ignore_Server_Idsfiltering is performed by the I/O thread, rather than by the SQL thread, which means that events which are filtered out are not written to the relay log. This differs from the filtering actions taken by server options such
--replicate-do-table, which apply to the SQL thread.
server_idvalue from the master.
server_uuidvalue from the master.
The location of the
The number of seconds that the slave must lag the master.
Waiting until MASTER_DELAY seconds after master executed event, this field contains the number of delay seconds remaining. At other times, this field is
The state of the SQL thread (analogous to
Slave_IO_State). The value is identical to the
Statevalue of the SQL thread as displayed by
SHOW PROCESSLIST. Section 9.14.6, “Replication Slave SQL Thread States”, provides a listing of possible states
The number of times the slave can attempt to reconnect to the master in the event of a lost connection. This value can be set using the
MASTER_RETRY_COUNToption of the
CHANGE MASTER TOstatement (preferred) or the older
--master-retry-countserver option (still supported for backward compatibility).
The network interface that the slave is bound to, if any. This is set using the
MASTER_BINDoption for the
CHANGE MASTER TOstatement.
A timestamp in
YYMMDD HH:MM:SSformat that shows when the most recent I/O error took place.
A timestamp in
YYMMDD HH:MM:SSformat that shows when the last SQL error occurred.
The set of global transaction IDs corresponding to all transactions received by this slave. Empty if GTIDs are not in use. See GTID Sets for more information.
This is the set of all GTIDs that exist or have existed in the relay logs. Each GTID is added as soon as the
Gtid_log_eventis received. This can cause partially transmitted transactions to have their GTIDs included in the set.
When all relay logs are lost due to executing
CHANGE MASTER TO, or due to the effects of the
--relay-log-recoveryoption, the set is cleared. When
relay_log_purge = 1, the newest relay log is always kept, and the set is not cleared.
The set of global transaction IDs written in the binary log. This is the same as the value for the global
gtid_executedsystem variable on this server, as well as the value for
Executed_Gtid_Setin the output of
SHOW MASTER STATUSon this server. Empty if GTIDs are not in use. See GTID Sets for more information.
1 if autopositioning is in use; otherwise 0.
Replicate_Rewrite_DBvalue displays any replication filtering rules that were specified. For example, if the following replication filter rule was set:
CHANGE REPLICATION FILTER REPLICATE_REWRITE_DB=((db1,db2), (db3,db4));
For more information, see Section 22.214.171.124, “CHANGE REPLICATION FILTER Syntax”.
The replication channel which is being displayed. There is always a default replication channel, and more replication channels can be added. See Section 19.2.3, “Replication Channels” for more information.