13.7.5.35. SHOW SLAVE STATUS Syntax

Slave_IO_State

A copy of the State field of the SHOW PROCESSLIST output 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 8.12.5.6, "Replication Slave I/O Thread States".

Master_Host

The master host that the slave is connected to.

Master_User

The user name of the account used to connect to the master.

Master_Port

The port used to connect to the master.

Connect_Retry

The number of seconds between connect retries (default 60). This can be set with the CHANGE MASTER TO statement.

Master_Log_File

The name of the master binary log file from which the I/O thread is currently reading.

Read_Master_Log_Pos

The position in the current master binary log file up to which the I/O thread has read.

Relay_Log_File

The name of the relay log file from which the SQL thread is currently reading and executing.

Relay_Log_Pos

The position in the current relay log file up to which the SQL thread has read and executed.

Relay_Master_Log_File

The name of the master binary log file containing the most recent event executed by the SQL thread.

Slave_IO_Running

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:

The value of the Slave_running system status variable corresponds with this value.

Slave_SQL_Running

Whether the SQL thread is started.

Replicate_Do_DB, Replicate_Ignore_DB

The lists of databases that were specified with the --replicate-do-db and --replicate-ignore-db options, if any.

Replicate_Do_Table, Replicate_Ignore_Table, Replicate_Wild_Do_Table, Replicate_Wild_Ignore_Table

The lists of tables that were specified with the --replicate-do-table, --replicate-ignore-table, --replicate-wild-do-table, and --replicate-wild-ignore-table options, if any.

Last_Errno, Last_Error

These columns are aliases for Last_SQL_Errno and Last_SQL_Error.

Issuing RESET MASTER or RESET SLAVE resets the values shown in these columns.

Skip_Counter

The current value of the sql_slave_skip_counter system variable. See Section 13.4.2.4, "SET GLOBAL sql_slave_skip_counter Syntax".

Exec_Master_Log_Pos

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 TO statement's MASTER_LOG_POS option when starting a new slave from an existing slave, so that the new slave reads from this point. The coordinates given by (Relay_Master_Log_File, Exec_Master_Log_Pos) in the master's binary log correspond to the coordinates given by (Relay_Log_File, Relay_Log_Pos) in the relay log.

When using a multi-threaded slave (by setting slave_parallel_workers to a nonzero value in MySQL 5.6.3 and later), the value in this column actually represents a "low-water" mark, before which no uncommitted transactions remain. Because the current implementation allows execution of transactions on different databases in a different order on the slave than on the master, this is not necessarily the position of the most recently executed transaction.

Relay_Log_Space

The total combined size of all existing relay log files.

Until_Condition, Until_Log_File, Until_Log_Pos

The values specified in the UNTIL clause of the START SLAVE statement.

Until_Condition has these values:

Until_Log_File and Until_Log_Pos indicate the log file name and position that define the coordinates at which the SQL thread stops executing.

Master_SSL_Allowed, Master_SSL_CA_File, Master_SSL_CA_Path, Master_SSL_Cert, Master_SSL_Cipher, Master_SSL_CRL_File, Master_SSL_CRL_Path, Master_SSL_Key, Master_SSL_Verify_Server_Cert

These fields show the SSL parameters used by the slave to connect to the master, if any.

Master_SSL_Allowed has these values:

The values of the other SSL-related fields correspond to the values of the MASTER_SSL_CA, MASTER_SSL_CAPATH, MASTER_SSL_CERT, MASTER_SSL_CIPHER, MASTER_SSL_CRL, MASTER_SSL_CRLPATH, MASTER_SSL_KEY, and MASTER_SSL_VERIFY_SERVER_CERT options to the CHANGE MASTER TO statement. See Section 13.4.2.1, "CHANGE MASTER TO Syntax".

Master_SSL_CRL_File and Master_SSL_CRL_Path were added in MySQL 5.6.3.

Seconds_Behind_Master

This field is an indication of how "late" the slave is:

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_Master often 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 Seconds_Behind_Master less reliable.

In MySQL 5.6.9 and later, 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. Previously, this field was NULL if the slave SQL thread or the slave I/O thread was not running or was not connected to the master. (Bug #12946333) For example, if (prior to MySQL 5.6.9) the slave I/O thread was running but was not connected to the master and was sleeping for the number of seconds given by the CHANGE MASTER TO statement or --master-connect-retry option (default 60) before reconnecting, the value was NULL. Now in such cases, the connection to the master is not tested; instead, if the I/O thread is running but the relay log is exhausted, Seconds_Behind_Master is set to 0.

The value of Seconds_Behind_Master is 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 TIMESTAMP successfully. However, the problem for Seconds_Behind_Master is that if M1 also receives direct updates from clients, the Seconds_Behind_Master value 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 (MySQL 5.6.3 and later), 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.

Last_IO_Errno, Last_IO_Error

The error number and error message of the last 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_Error value is not empty, the error values also appear in the slave's error log.

Beginning with MySQL 5.6.1, 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.

Previous to MySQL 5.6.3, this timestamp was prefixed to the error message text shown in the Last_IO_Error column. In MySQL 5.6.3 and later, the timestamp appears instead in the Last_SQL_Error_Timestamp column.

Issuing RESET MASTER or RESET SLAVE resets the values shown in these columns.

Last_SQL_Errno, Last_SQL_Error

The error number and error message of the last 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_Error value is not empty, the error values also appear in the slave's error log.

Beginning with MySQL 5.6.1, SQL error information includes a timestamp showing when the most recent SQL thread error occurred. This timestamp uses the format YYMMDD HH:MM:SS.

Previous to MySQL 5.6.3, this timestamp was prefixed to the error message text shown in the Last_SQL_Error column. In MySQL 5.6.3 and later, the timestamp appears instead in the Last_SQL_Error_Timestamp column.

Issuing RESET MASTER or RESET SLAVE resets the values shown in these columns.

Replicate_Ignore_Server_Ids

In MySQL 5.6, you can tell a slave to ignore events from 0 or more masters using the IGNORE_SERVER_IDS option in a CHANGE MASTER TO statement. This is normally of interest only when using a circular or other multi-master replication setup.

The message shown for Replicate_Ignore_Server_Ids consists of a space-delimited list of one or more numbers, the first value indicating the number of servers to be ignored; if not 0 (the default), this server-count value is followed by the actual server IDs. For example, if a CHANGE MASTER TO statement 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:

  Replicate_Ignore_Server_Ids: 3 2 6 9

Master_Server_Id

The server_id value from the master.

Master_UUID

The server_uuid value from the master. This field was added in MySQL 5.6.0.

Master_Info_File

The location of the master.info file. This field was added in MySQL 5.6.0.

SQL_Delay

The number of seconds that the slave must lag the master. This field was added in MySQL 5.6.0.

SQL_Remaining_Delay

When Slave_SQL_Running_State is Waiting until MASTER_DELAY seconds after master executed event, this field contains the number of seconds left of the delay. At other times, this field is NULL. This field was added in MySQL 5.6.0.

Slave_SQL_Running_State

The state of the SQL thread (analogous to Slave_IO_State). The value is identical to the State value of the SQL thread as displayed by SHOW PROCESSLIST; Section 8.12.5.7, "Replication Slave SQL Thread States", provides a listing of possible states. This field was added in MySQL 5.6.0.

Master_Retry_Count

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_COUNT option in a CHANGE MASTER TO statement (preferred) or the older --master-retry-count server option (still supported for backward compatibility). This field was added in MySQL 5.6.1.

Master_Bind

Shows the network interface that the slave is bound to, if any, set using the MASTER_BIND option for the CHANGE MASTER TO statement.

This column was added in MySQL 5.6.2.

Last_IO_Error_Timestamp

A timestamp in YYMMDD HH:MM:SS format that shows when the most recent I/O error took place.

This column was added in MySQL 5.6.3. Previously in MySQL 5.6, this timestamp was prepended to the error text shown in Last_IO_Error.

Last_SQL_Error_Timestamp

A timestamp in YYMMDD HH:MM:SS format that shows when the last SQL error occurred.

This column was added in MySQL 5.6.3. Previously in MySQL 5.6, this timestamp was prepended to the error text shown in Last_SQL_Error.

Retrieved_Gtid_Set

The set of global transaction IDs corresponding to all transactions received by this slave. Empty if GTIDs are not in use.

This column was added in MySQL 5.6.5.

Prior to MySQL 5.6.10, this value was printed using uppercase. In MySQL 5.6.10 and later, it is always printed using lowercase. (Bug #15869441)

Executed_Gtid_Set

The set of global transaction IDs for all received transactions subsequently executed on this slave. Empty if GTIDs are not in use.

This column was added in MySQL 5.6.5.

Prior to MySQL 5.6.10, this value was printed using uppercase. In MySQL 5.6.10 and later, it is always printed using lowercase. (Bug #15869441)

Auto_Position

The value of this column is 1 if autopositioning is in use; otherwise it is 0.

This column was added in MySQL 5.6.10. (Bug #15992220)