13.7.6.34 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 8.14.4, “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 names of any databases that were specified with the --replicate-do-db and --replicate-ignore-db options, or the CHANGE REPLICATION FILTER statement. If the FOR CHANNEL clause was used, the channel specific replication filters are shown. Otherwise, the replication filters for every replication channel are shown.

Replicate_Do_Table, Replicate_Ignore_Table, Replicate_Wild_Do_Table, Replicate_Wild_Ignore_Table

The names of any tables that were specified with the --replicate-do-table, --replicate-ignore-table, --replicate-wild-do-table, and --replicate-wild-ignore-table options, or the CHANGE REPLICATION FILTER statement. If the FOR CHANNEL clause was used, the channel specific replication filters are shown. Otherwise, the replication filters for every replication channel are shown.

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 13.4.2.5, “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.

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 17.4.1.33, “Replication and Transaction Inconsistencies” for more information.

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.

For more information on UNTIL clauses, see Section 13.4.2.6, “START SLAVE Syntax”.

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”.

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 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 NULL if 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_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 multithreaded 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.

Last_IO_Errno, Last_IO_Error

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_Error value 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 Last_IO_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 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_Error value is not empty, the error values also appear in the slave's error log.

If the slave is multithreaded, the SQL thread is the coordinator for worker threads. In this case, the Last_SQL_Error field shows exactly what the Last_Error_Message column in the Performance Schema replication_applier_status_by_coordinator table 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_worker table 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_worker table should also be used to learn more about the failure shown by SHOW SLAVE STATUS or 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 Last_SQL_Error_Timestamp column.

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

In MySQL 8.0, all error codes and messages displayed in the Last_SQL_Errno and Last_SQL_Error columns correspond to error values listed in Section B.3.1, “Server Error Message Reference”. This was not always true in previous versions. (Bug #11760365, Bug #52768)

Replicate_Ignore_Server_Ids

Any server IDs that have been specified using the IGNORE_SERVER_IDS option of the CHANGE MASTER TO statement, so that the slave ignores events from these servers. This option is used in a circular or other multi-master replication setup when one of the servers is removed. If any server IDs have been set in this way, a comma-delimited list of one or more numbers is shown. If no server IDs have been set, the field is blank.

	Replicate_Ignore_Server_Ids: 2, 6, 9

	Ignored_server_ids: 3, 2, 6, 9

Replicate_Ignore_Server_Ids filtering 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.

Master_Server_Id

The server_id value from the master.

Master_UUID

The server_uuid value from the master.

Master_Info_File

The location of the master.info file, if a file rather than a table is used for the slave's master info repository. The use of a file for the master info log has been superseded by crash-safe slave tables, and the master_info_repository=FILE setting is deprecated.

SQL_Delay

The number of seconds that the slave must lag the master.

SQL_Remaining_Delay

When Slave_SQL_Running_State is Waiting until MASTER_DELAY seconds after master executed event, this field contains the number of delay seconds remaining. At other times, this field is NULL.

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 8.14.5, “Replication Slave SQL Thread States”, provides a listing of possible states

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 of the CHANGE MASTER TO statement (preferred) or the older --master-retry-count server option (still supported for backward compatibility).

Master_Bind

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

Last_IO_Error_Timestamp

A timestamp in YYMMDD hh:mm:ss format that shows when the most recent I/O error took place.

Last_SQL_Error_Timestamp

A timestamp in YYMMDD hh:mm:ss format that shows when the most recent SQL error occurred.

Retrieved_Gtid_Set

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_event is received. This can cause partially transmitted transactions to have their GTIDs included in the set.

When all relay logs are lost due to executing RESET SLAVE or CHANGE MASTER TO, or due to the effects of the --relay-log-recovery option, the set is cleared. When relay_log_purge = 1, the newest relay log is always kept, and the set is not cleared.

Executed_Gtid_Set

The set of global transaction IDs written in the binary log. This is the same as the value for the global gtid_executed system variable on this server, as well as the value for Executed_Gtid_Set in the output of SHOW MASTER STATUS on this server. Empty if GTIDs are not in use. See GTID Sets for more information.

Auto_Position

1 if autopositioning is in use; otherwise 0.

Replicate_Rewrite_DB

The Replicate_Rewrite_DB value displays any replication filtering rules that were specified. For example, if the following replication filter rule was set:

the Replicate_Rewrite_DB value displays:

Replicate_Rewrite_DB: (db1,db2),(db3,db4)

For more information, see Section 13.4.2.2, “CHANGE REPLICATION FILTER Syntax”.

Channel_name

The replication channel which is being displayed. There is always a default replication channel, and more replication channels can be added. See Section 17.2.3, “Replication Channels” for more information.

Master_TLS_Version

The TLS version used on the master. For TLS version information, see Section 6.3.2, “Encrypted Connection Protocols and Ciphers”.

Master_public_key_path

The path name to a file containing a slave-side copy of the public key required by the master for RSA key pair-based password exchange. The file must be in PEM format. This column applies to slaves that authenticate with the sha256_password or caching_sha2_password authentication plugin.

If Master_public_key_path is given and specifies a valid public key file, it takes precedence over Get_master_public_key.

Get_master_public_key

Whether to request from the master the public key required for RSA key pair-based password exchange. This column applies to slaves that authenticate with the caching_sha2_password authentication plugin. For that plugin, the master does not send the public key unless requested.

If Master_public_key_path is given and specifies a valid public key file, it takes precedence over Get_master_public_key.