Replica_IO_State

A copy of the State field of the SHOW PROCESSLIST output for the replica I/O thread. This tells you what the thread is doing: trying to connect to the source, waiting for events from the source, reconnecting to the source, and so on. For a listing of possible states, see Section 8.14.5, “Replication I/O Thread States”.

Source_Host

The source host that the replica is connected to.

Source_User

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

Source_Port

The port used to connect to the source.

Connect_Retry

The number of seconds between connect retries (default 60). This can be set with a CHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23).

Source_Log_File

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

Read_Source_Log_Pos

The position in the current source 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_Source_Log_File

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

Replica_IO_Running

Whether the replication I/O thread is started and has connected successfully to the source. Internally, the state of this thread is represented by one of the following three values:

Replica_SQL_Running

Whether the replication 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 REPLICA | SLAVE resets the values shown in these columns.

Skip_Counter

The current value of the sql_slave_skip_counter system variable. See SET GLOBAL sql_slave_skip_counter Statement.

Exec_Source_Log_Pos

The position in the current source binary log file to which the replication 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 REPLICATION SOURCE TO statement's SOURCE_LOG_POS option (from MySQL 8.0.23) or the CHANGE MASTER TO statement's MASTER_LOG_POS option (before MySQL 8.0.23) when starting a new replica from an existing replica, so that the new replica reads from this point. The coordinates given by (Relay_Source_Log_File, Exec_Source_Log_Pos) in the source'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 REPLICA | SLAVE UNTIL SQL_AFTER_MTS_GAPS. See Section 17.5.1.34, “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 REPLICA | 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 replication SQL thread stops executing.

For more information on UNTIL clauses, see Section 13.4.2.8, “START SLAVE | REPLICA Statement”.

Source_SSL_Allowed, Source_SSL_CA_File, Source_SSL_CA_Path, Source_SSL_Cert, Source_SSL_Cipher, Source_SSL_CRL_File, Source_SSL_CRL_Path, Source_SSL_Key, Source_SSL_Verify_Server_Cert

These fields show the SSL parameters used by the replica to connect to the source, if any.

Source_SSL_Allowed has these values:

The values of the other SSL-related fields correspond to the values of the SOURCE_SSL_* options of the CHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23), or the MASTER_SSL_* options of the CHANGE MASTER TO statement (before MySQL 8.0.23). See Section 13.4.2.1, “CHANGE MASTER TO Statement”.

Seconds_Behind_Source

This field is an indication of how “late” the replica is:

In essence, this field measures the time difference in seconds between the replication SQL thread and the replication I/O thread. If the network connection between source and replica is fast, the replication I/O thread is very close to the source, so this field is a good approximation of how late the replication SQL thread is compared to the source. If the network is slow, this is not a good approximation; the replication SQL thread may quite often be caught up with the slow-reading replication I/O thread, so Seconds_Behind_Source often shows a value of 0, even if the replication I/O thread is late compared to the source. In other words, this column is useful only for fast networks.

This time difference computation works even if the source and replica do not have identical clock times, provided that the difference, computed when the replica 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_Source less reliable.

In MySQL 8.0, this field is NULL (undefined or unknown) if the replication SQL thread is not running, or if the SQL thread has consumed all of the relay log and the replication I/O thread is not running. (In older versions of MySQL, this field was NULL if the replication SQL thread or the replication I/O thread was not running or was not connected to the source.) If the replication I/O thread is running but the relay log is exhausted, Seconds_Behind_Source is set to 0.

The value of Seconds_Behind_Source is based on the timestamps stored in events, which are preserved through replication. This means that if a source M1 is itself a replica 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_Source is that if M1 also receives direct updates from clients, the Seconds_Behind_Source 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 replica, you should keep in mind that this value is based on Exec_Source_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 replication 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 replica'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 REPLICA | 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 replication 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 replica's error log.

If the replica is multithreaded, the replication 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 replica 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 REPLICA | 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 REPLICA | 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 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 REPLICATION SOURCE TO | CHANGE MASTER TO statement, so that the replica ignores events from these servers. This option is used in a circular or other multi-source 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.

Source_Server_Id

The server_id value from the source.

Source_UUID

The server_uuid value from the source.

Source_Info_File

The location of the master.info file, the use of which is now deprecated. By default from MySQL 8.0, a table is used instead for the replica's connection metadata repository.

SQL_Delay

The number of seconds that the replica must lag the source.

SQL_Remaining_Delay

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

Replica_SQL_Running_State

The state of the SQL thread (analogous to Replica_IO_State). The value is identical to the State value of the SQL thread as displayed by SHOW PROCESSLIST. Section 8.14.6, “Replication SQL Thread States”, provides a listing of possible states.

Source_Retry_Count

The number of times the replica can attempt to reconnect to the source in the event of a lost connection. This value can be set using the SOURCE_RETRY_COUNT | MASTER_RETRY_COUNT option of the CHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23), or the older --master-retry-count server option (still supported for backward compatibility).

Source_Bind

The network interface that the replica is bound to, if any. This is set using the SOURCE_BIND | MASTER_BIND option for the CHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23).

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 replica. 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 REPLICA | SLAVE or CHANGE REPLICATION SOURCE TO | 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 GTID auto-positioning is in use for the channel, 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:

CHANGE REPLICATION FILTER REPLICATE_REWRITE_DB=((db1,db2), (db3,db4));

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 Statement”.

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 17.2.2, “Replication Channels” for more information.

Master_TLS_Version

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

Source_public_key_path

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

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

Get_source_public_key

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

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

Network_Namespace

The network namespace name; empty if the connection uses the default (global) namespace. For information about network namespaces, see Section 5.1.14, “Network Namespace Support”. This column was added in MySQL 8.0.22.