Syntax:
SHOW {REPLICA | SLAVE} STATUS [FOR CHANNEL channel]

This statement provides status information on essential parameters of
the replica threads. From MySQL 8.0.22, use SHOW REPLICA STATUS in
place of SHOW SLAVE STATUS, which is deprecated from that release. In
releases before MySQL 8.0.22, use SHOW SLAVE STATUS. The statement
requires the REPLICATION CLIENT privilege (or the deprecated SUPER
privilege).

SHOW REPLICA STATUS is nonblocking. When run concurrently with STOP
REPLICA, SHOW REPLICA STATUS returns without waiting for STOP REPLICA
to finish shutting down the replication SQL (applier) thread or
replication I/O (receiver) thread (or both). This permits use in
monitoring and other applications where getting an immediate response
from SHOW REPLICA STATUS is more important than ensuring that it
returned the latest data. The SLAVE keyword was replaced with REPLICA
in MySQL 8.0.22.

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 layout:

mysql> SHOW REPLICA STATUS\G
*************************** 1. row ***************************
             Replica_IO_State: Waiting for source to send event
                  Source_Host: localhost
                  Source_User: repl
                  Source_Port: 13000
                Connect_Retry: 60
              Source_Log_File: source-bin.000002
          Read_Source_Log_Pos: 1307
               Relay_Log_File: replica-relay-bin.000003
                Relay_Log_Pos: 1508
        Relay_Source_Log_File: source-bin.000002
           Replica_IO_Running: Yes
          Replica_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_Source_Log_Pos: 1307
              Relay_Log_Space: 1858
              Until_Condition: None
               Until_Log_File:
                Until_Log_Pos: 0
           Source_SSL_Allowed: No
           Source_SSL_CA_File:
           Source_SSL_CA_Path:
              Source_SSL_Cert:
            Source_SSL_Cipher:
               Source_SSL_Key:
        Seconds_Behind_Source: 0
Source_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error:
               Last_SQL_Errno: 0
               Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
             Source_Server_Id: 1
                  Source_UUID: 3e11fa47-71ca-11e1-9e33-c80aa9429562
             Source_Info_File:
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
    Replica_SQL_Running_State: Reading event from the relay log
           Source_Retry_Count: 10
                  Source_Bind:
      Last_IO_Error_Timestamp:
     Last_SQL_Error_Timestamp:
               Source_SSL_Crl:
           Source_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:
           Source_TLS_Version: TLSv1.2
       Source_public_key_path: public_key.pem
        Get_source_public_key: 0
            Network_Namespace:

The Performance Schema provides tables that expose replication
information. This is similar to the information available from the SHOW
REPLICA STATUS statement, but represented in table form. For details,
see
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-replication-
tables.html.

From MySQL 8.0.27, you can set the GTID_ONLY option on the CHANGE
REPLICATION SOURCE TO statement to stop a replication channel from
persisting file names and file positions in the replication metadata
repositories. With this setting, file positions for the source binary
log file and the relay log file are tracked in memory. The SHOW REPLICA
STATUS statement still displays file positions in normal use. However,
because the file positions are not being regularly updated in the
connection metadata repository and the applier metadata repository
except in a few situations, they are likely to be out of date if the
server is restarted.

For a replication channel with the GTID_ONLY setting after a server
start, the read and applied file positions for the source binary log
file (Read_Source_Log_Pos and Exec_Source_Log_Pos) are set to zero, and
the file names (Source_Log_File and Relay_Source_Log_File) are set to
INVALID. The relay log file name (Relay_Log_File) is set according to
the relay_log_recovery setting, either a new file that was created at
server start or the first relay log file present. The file position
(Relay_Log_Pos) is set to position 4, and GTID auto-skip is used to
skip any transactions in the file that were already applied.

When the receiver thread contacts the source and gets valid position
information, the read position (Read_Source_Log_Pos) and file name
(Source_Log_File) are updated with the correct data and become valid.
When the applier thread applies a transaction from the source, or skips
an already executed transaction, the executed position
(Exec_Source_Log_Pos) and file name (Relay_Source_Log_File) are updated
with the correct data and become valid. The relay log file position
(Relay_Log_Pos) is also updated at that time.

URL: https://dev.mysql.com/doc/refman/8.0/en/show-replica-status.html

