MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0
CHANGE REPLICATION SOURCE TOoption
[,option
] ... [channel_option
]option
: { SOURCE_BIND = 'interface_name
' | SOURCE_HOST = 'host_name
' | SOURCE_USER = 'user_name
' | SOURCE_PASSWORD = 'password
' | SOURCE_PORT =port_num
| PRIVILEGE_CHECKS_USER = {'account
' | NULL} | REQUIRE_ROW_FORMAT = {0|1} | REQUIRE_TABLE_PRIMARY_KEY_CHECK = {STREAM | ON | OFF} | ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS = {OFF | LOCAL |uuid
} | SOURCE_LOG_FILE = 'source_log_name
' | SOURCE_LOG_POS =source_log_pos
| SOURCE_AUTO_POSITION = {0|1} | RELAY_LOG_FILE = 'relay_log_name
' | RELAY_LOG_POS =relay_log_pos
| SOURCE_HEARTBEAT_PERIOD =interval
| SOURCE_CONNECT_RETRY =interval
| SOURCE_RETRY_COUNT =count
| SOURCE_CONNECTION_AUTO_FAILOVER = {0|1} | SOURCE_DELAY =interval
| SOURCE_COMPRESSION_ALGORITHMS = 'value
' | SOURCE_ZSTD_COMPRESSION_LEVEL =level
| SOURCE_SSL = {0|1} | SOURCE_SSL_CA = 'ca_file_name
' | SOURCE_SSL_CAPATH = 'ca_directory_name
' | SOURCE_SSL_CERT = 'cert_file_name
' | SOURCE_SSL_CRL = 'crl_file_name
' | SOURCE_SSL_CRLPATH = 'crl_directory_name
' | SOURCE_SSL_KEY = 'key_file_name
' | SOURCE_SSL_CIPHER = 'cipher_list
' | SOURCE_SSL_VERIFY_SERVER_CERT = {0|1} | SOURCE_TLS_VERSION = 'protocol_list
' | SOURCE_TLS_CIPHERSUITES = 'ciphersuite_list
' | SOURCE_PUBLIC_KEY_PATH = 'key_file_name
' | GET_SOURCE_PUBLIC_KEY = {0|1} | NETWORK_NAMESPACE = 'namespace
' | IGNORE_SERVER_IDS = (server_id_list
) }channel_option
: FOR CHANNELchannel
server_id_list
: [server_id
[,server_id
] ... ]
CHANGE REPLICATION SOURCE TO
changes the parameters that the replica server uses for
connecting to the source and for reading data from the source.
It also updates the contents of the replication metadata
repositories (see Section 17.2.4, “Relay Log and Replication Metadata Repositories”). From MySQL
8.0.23, use CHANGE REPLICATION SOURCE
TO
in place of CHANGE MASTER
TO
, which is deprecated from that release. In releases
before MySQL 8.0.23, use CHANGE MASTER
TO
.
You can issue CHANGE REPLICATION SOURCE
TO
statements on a running replica without first
stopping it, depending on the states of the replication SQL
thread and replication I/O thread. The rules governing such use
are provided later in this section. CHANGE
REPLICATION SOURCE TO
requires the
REPLICATION_SLAVE_ADMIN
privilege
(or the deprecated SUPER
privilege).
When using a multithreaded replica (in other words
slave_parallel_workers
is
greater than 0), stopping the replica can cause
“gaps” in the sequence of transactions that have
been executed from the relay log, regardless of whether the
replica was stopped intentionally or otherwise. When such gaps
exist, issuing CHANGE REPLICATION SOURCE
TO
fails. The solution in this situation is to issue
START REPLICA
UNTIL SQL_AFTER_MTS_GAPS
which ensures that the gaps
are closed.
The optional FOR CHANNEL
clause enables you
to name which replication channel the statement applies to.
Providing a channel
FOR CHANNEL
clause applies the
channel
CHANGE REPLICATION SOURCE TO
statement to a specific replication channel, and is used to add
a new channel or modify an existing channel. For example, to add
a new channel called channel2
:
CHANGE REPLICATION SOURCE TO SOURCE_HOST=host1, SOURCE_PORT=3002 FOR CHANNEL 'channel2'
If no clause is named and no extra channels exist, the statement applies to the default channel.
When using multiple replication channels, if a
CHANGE REPLICATION SOURCE TO
statement does not name a channel using a FOR CHANNEL
clause, an error
occurs. See Section 17.2.2, “Replication Channels” for more
information.
channel
Values used for SOURCE_HOST
and other
CHANGE REPLICATION SOURCE TO
options are checked for linefeed (\n
or
0x0A
) characters. The presence of such
characters in these values causes the statement to fail with
ER_MASTER_INFO
.
Invoking CHANGE REPLICATION SOURCE
TO
causes the previous values for
SOURCE_HOST
, SOURCE_PORT
,
SOURCE_LOG_FILE
, and
SOURCE_LOG_POS
to be written to the error
log, along with other information about the replica's state
prior to execution.
CHANGE REPLICATION SOURCE TO
causes an implicit commit of an ongoing transaction. See
Section 13.3.3, “Statements That Cause an Implicit Commit”.
For some of the options of the CHANGE
REPLICATION SOURCE TO
statement, you must issue a
STOP
REPLICA
statement prior to issuing a
CHANGE REPLICATION SOURCE TO
statement (and a
START
REPLICA
statement afterwards). Sometimes, you only
need to stop the replication SQL thread or the replication I/O
thread, not both:
When the SQL thread is stopped, you can execute
CHANGE REPLICATION SOURCE TO
using any combination that is otherwise allowed of
RELAY_LOG_FILE
,
RELAY_LOG_POS
, and
SOURCE_DELAY
options, even if the
replication I/O thread is running. No other options may be
used with this statement when the I/O thread is running.
When the I/O thread is stopped, you can execute
CHANGE REPLICATION SOURCE TO
using any of the options for this statement (in any allowed
combination) except
RELAY_LOG_FILE
,
RELAY_LOG_POS
,
SOURCE_DELAY
, or
SOURCE_AUTO_POSITION = 1
even when the
SQL thread is running.
Both the SQL thread and the I/O thread must be stopped
before issuing a CHANGE REPLICATION
SOURCE TO
statement that employs
SOURCE_AUTO_POSITION = 1
or
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
.
You can check the current state of the replication SQL thread
and replication I/O thread using
SHOW
REPLICA STATUS
. Note that the Group Replication
applier channel (group_replication_applier
)
has no I/O thread, only an SQL thread.
For more information, see Section 17.4.8, “Switching Sources During Failover”.
If you are using statement-based replication and temporary
tables, it is possible for a CHANGE
REPLICATION SOURCE TO
statement following a
STOP
REPLICA
statement to leave behind temporary tables on
the replica. A warning
(ER_WARN_OPEN_TEMP_TABLES_MUST_BE_ZERO
)
is now issued whenever this occurs. You can avoid this in such
cases by making sure that the value of the
Slave_open_temp_tables
system
status variable is equal to 0 prior to executing such a
CHANGE REPLICATION SOURCE TO
statement.
CHANGE REPLICATION SOURCE TO
is
useful for setting up a replica when you have the snapshot of
the source and have recorded the source's binary log coordinates
corresponding to the time of the snapshot. After loading the
snapshot into the replica to synchronize it with the source, you
can run CHANGE REPLICATION SOURCE TO
SOURCE_LOG_FILE='
on
the replica to specify the coordinates at which the replica
should begin reading the source's binary log.
log_name
',
SOURCE_LOG_POS=log_pos
The following example changes the source server the replica uses and establishes the source's binary log coordinates from which the replica begins reading:
CHANGE REPLICATION SOURCE TO
SOURCE_HOST='source2.example.com',
SOURCE_USER='replication',
SOURCE_PASSWORD='password
',
SOURCE_PORT=3306,
SOURCE_LOG_FILE='source2-bin.001',
SOURCE_LOG_POS=4,
SOURCE_CONNECT_RETRY=10;
The next example shows an operation that is less frequently
employed. It is used when the replica has relay log files that
you want it to execute again for some reason. To do this, the
source need not be reachable. You need only use
CHANGE REPLICATION SOURCE TO
and
start the SQL thread
(START REPLICA
SQL_THREAD
):
CHANGE REPLICATION SOURCE TO RELAY_LOG_FILE='replica-relay-bin.006', RELAY_LOG_POS=4025;
Options that you do not specify on a CHANGE
REPLICATION SOURCE TO
statement retain their value,
except as indicated in the following discussion. Thus, in most
cases, there is no need to specify options that do not change.
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
Makes the replication channel assign a GTID to replicated
transactions that do not have one, enabling replication
from a source that does not use GTID-based replication, to
a replica that does. For a multi-source replica, you can
have a mix of channels that use
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
,
and channels that do not. The default is
OFF
, meaning that the feature is not
used.
LOCAL
assigns a GTID including the
replica's own UUID (the
server_uuid
setting).
assigns
a GTID including the specified UUID, such as the
uuid
server_uuid
setting for
the replication source server. Using a nonlocal UUID lets
you differentiate between transactions that originated on
the replica and transactions that originated on the
source, and for a multi-source replica, between
transactions that originated on different sources. The
UUID you choose only has significance for the replica's
own use. If any of the transactions sent by the source do
have a GTID already, that GTID is retained.
Channels specific to Group Replication cannot use
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
,
but an asynchronous replication channel for another source
on a server instance that is a Group Replication group
member can do so. In that case, do not specify the Group
Replication group name as the UUID for creating the GTIDs.
To set
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
to LOCAL
or
, the
replica must have
uuid
gtid_mode=ON
set, and
this cannot be changed afterwards. This option is for use
with a source that has binary log file position based
replication, so MASTER_AUTO_POSITION=1
cannot be set for the channel. Both the replication SQL
thread and the replication I/O thread must be stopped
before setting this option.
A replica set up with
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
on any channel cannot be promoted to replace the
replication source server in the event that a failover
is required, and a backup taken from the replica cannot
be used to restore the replication source server. The
same restriction applies to replacing or restoring other
replicas that use
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
on any channel.
For further restrictions and information, see Section 17.1.3.6, “Replication From a Source Without GTIDs to a Replica With GTIDs”.
GET_SOURCE_PUBLIC_KEY
Enables RSA key pair-based password exchange by requesting
the public key from the source. This option applies to
replicas that authenticate with the
caching_sha2_password
authentication
plugin. For connections by accounts that authenticate
using this plugin, the source does not send the public key
unless requested, so it must be requested or specified in
the client. If SOURCE_PUBLIC_KEY_PATH
is given and specifies a valid public key file, it takes
precedence over GET_SOURCE_PUBLIC_KEY
.
If you are using a replication user account that
authenticates with the
caching_sha2_password
plugin (which is
the default from MySQL 8.0), and you are not using a
secure connection, you must specify either this option or
the SOURCE_PUBLIC_KEY_PATH
option to
provide the RSA public key to the replica.
IGNORE_SERVER_IDS
Makes the replica ignore events originating from the specified servers. The option takes a comma-separated list of 0 or more server IDs. Log rotation and deletion events from the servers are not ignored, and are recorded in the relay log.
In circular replication, the originating server normally
acts as the terminator of its own events, so that they are
not applied more than once. Thus, this option is useful in
circular replication when one of the servers in the circle
is removed. Suppose that you have a circular replication
setup with 4 servers, having server IDs 1, 2, 3, and 4,
and server 3 fails. When bridging the gap by starting
replication from server 2 to server 4, you can include
IGNORE_SERVER_IDS = (3)
in the
CHANGE REPLICATION SOURCE
TO
statement that you issue on server 4 to tell
it to use server 2 as its source instead of server 3.
Doing so causes it to ignore and not to propagate any
statements that originated with the server that is no
longer in use.
If IGNORE_SERVER_IDS
contains the
server's own ID and the server was started with the
--replicate-same-server-id
option enabled, an error results.
When global transaction identifiers (GTIDs) are used for
replication, transactions that have already been applied
are automatically ignored, so the
IGNORE_SERVER_IDS
function is not
required and is deprecated. If
gtid_mode=ON
is set for
the server, a deprecation warning is issued if you
include the IGNORE_SERVER_IDS
option
in a CHANGE REPLICATION SOURCE
TO
statement.
The source metadata repository and the output of
SHOW
REPLICA STATUS
provide the list of servers that
are currently ignored. For more information, see
Section 17.2.4.2, “Replication Metadata Repositories”, and
Section 13.7.7.35, “SHOW REPLICA | SLAVE STATUS Statement”.
If a CHANGE REPLICATION SOURCE
TO
statement is issued without any
IGNORE_SERVER_IDS
option, any existing
list is preserved. To clear the list of ignored servers,
it is necessary to use the option with an empty list:
CHANGE REPLICATION SOURCE TO IGNORE_SERVER_IDS = ();
RESET
REPLICA ALL
clears
IGNORE_SERVER_IDS
.
A deprecation warning is issued if SET
GTID_MODE=ON
is issued when any channel has
existing server IDs set with
IGNORE_SERVER_IDS
. Before starting
GTID-based replication, check for and clear all ignored
server ID lists on the servers involved. The
SHOW
REPLICA STATUS
statement displays the list of
ignored IDs, if there is one. If you do receive the
deprecation warning, you can still clear a list after
gtid_mode=ON
is set by
issuing a CHANGE REPLICATION SOURCE
TO
statement containing the
IGNORE_SERVER_IDS
option with an
empty list.
NETWORK_NAMESPACE
The network namespace to use for TCP/IP connections to the
replication source server. If this option is omitted,
connections from the replica use the default (global)
namespace. On platforms that do not implement network
namespace support, failure occurs when the replica
attempts to connect to the source. For information about
network namespaces, see
Section 5.1.14, “Network Namespace Support”.
NETWORK_NAMESPACE
is available as of
MySQL 8.0.22.
PRIVILEGE_CHECKS_USER
Names a user account that supplies a security context for
the specified channel. NULL
, which is
the default, means no security context is used.
PRIVILEGE_CHECKS_USER
is available as
of MySQL 8.0.18.
The user name and host name for the user account must
follow the syntax described in
Section 6.2.4, “Specifying Account Names”, and the user must not be
an anonymous user (with a blank user name) or the
CURRENT_USER
. The account must have the
REPLICATION_APPLIER
privilege, plus the required privileges to execute the
transactions replicated on the channel. For details of the
privileges required by the account, see
Section 17.3.3, “Replication Privilege Checks”. When you
restart the replication channel, the privilege checks are
applied from that point on. If you do not specify a
channel and no other channels exist, the statement is
applied to the default channel.
The use of row-based binary logging is strongly
recommended when PRIVILEGE_CHECKS_USER
is set, and you can set
REQUIRE_ROW_FORMAT
to enforce this. For
example, to start privilege checks on the channel
channel_1
on a running replica, issue
the following statements:
mysql> STOP REPLICA FOR CHANNEL 'channel_1'; mysql> CHANGE REPLICATION SOURCE TO PRIVILEGE_CHECKS_USER = 'priv_repl
'@'%.example.com
', REQUIRE_ROW_FORMAT = 1, FOR CHANNEL 'channel_1'; mysql> START REPLICA FOR CHANNEL 'channel_1';
RELAY_LOG_FILE
,
RELAY_LOG_POS
The relay log file name, and the location in that file, at
which the replication SQL thread begins reading from the
replica's relay log the next time the thread starts. You
cannot use these options if you use
SOURCE_LOG_FILE
or
SOURCE_LOG_POS
.
RELAY_LOG_FILE
can use either an
absolute or relative path, and uses the same base name as
SOURCE_LOG_FILE
. A CHANGE
REPLICATION SOURCE TO
statement using
RELAY_LOG_FILE
,
RELAY_LOG_POS
, or both options can be
executed on a running replica when the replication SQL
thread is stopped. Relay logs are preserved if at least
one of the replication SQL thread and the replication I/O
thread is running. If both threads are stopped, all relay
log files are deleted unless at least one of
RELAY_LOG_FILE
or
RELAY_LOG_POS
is specified. Note that
the Group Replication applier channel
(group_replication_applier
) has no I/O
thread, only an SQL thread. For this channel, the relay
logs are not preserved when the SQL thread is stopped.
REQUIRE_ROW_FORMAT
Permits only row-based replication events to be processed
by the replication channel. This option prevents the
replication applier from taking actions such as creating
temporary tables and executing LOAD DATA
INFILE
requests, which increases the security of
the channel. Group Replication channels are automatically
created with REQUIRE_ROW_FORMAT
set,
and you cannot change the option for those channels. For
more information, see
Section 17.3.3, “Replication Privilege Checks”.
REQUIRE_ROW_FORMAT
is available as of
MySQL 8.0.19.
REQUIRE_TABLE_PRIMARY_KEY_CHECK
Enables a replica to select its own policy for primary key
checks. When the option is set to ON
for a replication channel, the replica always uses the
value ON
for the
sql_require_primary_key
system variable in replication operations, requiring a
primary key. When the option is set to
OFF
, the replica always uses the value
OFF
for the
sql_require_primary_key
system variable in replication operations, so that a
primary key is never required, even if the source required
one. When the
REQUIRE_TABLE_PRIMARY_KEY_CHECK
option
is set to STREAM
, which is the default,
the replica uses whatever value is replicated from the
source for each transaction.
REQUIRE_TABLE_PRIMARY_KEY_CHECK
is
available as of MySQL 8.0.20.
For multisource replication, setting
REQUIRE_TABLE_PRIMARY_KEY_CHECK
to
ON
or OFF
enables a
replica to normalize behavior across the replication
channels for different sources, and keep a consistent
setting for the
sql_require_primary_key
system variable. Using ON
safeguards
against the accidental loss of primary keys when multiple
sources update the same set of tables. Using
OFF
allows sources that can manipulate
primary keys to work alongside sources that cannot.
When PRIVILEGE_CHECKS_USER
is set,
setting REQUIRE_TABLE_PRIMARY_KEY_CHECK
to ON
or OFF
means
that the user account does not need session administration
level privileges to set restricted session variables,
which are required to change the value of
sql_require_primary_key
to match the source's setting for each transaction. For
more information, see
Section 17.3.3, “Replication Privilege Checks”.
SOURCE_AUTO_POSITION
Makes the replica attempt to connect to the source using
GTID-based replication. This option can be used with
CHANGE REPLICATION SOURCE TO
only if
both the replication SQL thread and replication I/O thread
are stopped.
Both the replica and the source must have GTIDs enabled
(GTID_MODE=ON
,
ON_PERMISSIVE,
or
OFF_PERMISSIVE
on the replica, and
GTID_MODE=ON
on the
source). Auto-positioning is used for the connection, so
the coordinates represented by
SOURCE_LOG_FILE
and
SOURCE_LOG_POS
are not used, and the
use of either or both of these options together with
SOURCE_AUTO_POSITION = 1
causes an
error. If multi-source replication is enabled on the
replica, you need to set the SOURCE_AUTO_POSITION
= 1
option for each applicable replication
channel.
With SOURCE_AUTO_POSITION = 1
set, in
the initial connection handshake, the replica sends a GTID
set containing the transactions that it has already
received, committed, or both. The source responds by
sending all transactions recorded in its binary log whose
GTID is not included in the GTID set sent by the replica.
This exchange ensures that the source only sends the
transactions with a GTID that the replica has not already
recorded or committed. If the replica receives
transactions from more than one source, as in the case of
a diamond topology, the auto-skip function ensures that
the transactions are not applied twice. For details of how
the GTID set sent by the replica is computed, see
Section 17.1.3.3, “GTID Auto-Positioning”.
If any of the transactions that should be sent by the
source have been purged from the source's binary log, or
added to the set of GTIDs in the
gtid_purged
system
variable by another method, the source sends the error
ER_MASTER_HAS_PURGED_REQUIRED_GTIDS
to the replica, and replication does not start. The GTIDs
of the missing purged transactions are identified and
listed in the source's error log in the warning message
ER_FOUND_MISSING_GTIDS. Also, if
during the exchange of transactions it is found that the
replica has recorded or committed transactions with the
source's UUID in the GTID, but the source itself has not
committed them, the source sends the error
ER_SLAVE_HAS_MORE_GTIDS_THAN_MASTER
to the replica and replication does not start. For
information on how to handle these situations, see
Section 17.1.3.3, “GTID Auto-Positioning”.
You can see whether replication is running with GTID
auto-positioning enabled by checking the Performance
Schema
replication_connection_status
table or the output of
SHOW
REPLICA STATUS
. Disabling the
SOURCE_AUTO_POSITION
option again makes
the replica revert to file-based replication, in which
case you must also specify one or both of the
SOURCE_LOG_FILE
or
SOURCE_LOG_POS
options.
SOURCE_BIND
Determines which of the replica's network interfaces is
chosen for connecting to the source, for use on replicas
that have multiple network interfaces. The address
configured with this option, if any, can be seen in the
Source_Bind
column of the output from
SHOW
REPLICA STATUS
. In the source metadata
repository table
mysql.slave_master_info
, the value can
be seen as the Source_bind
column. The
ability to bind a replica to a specific network interface
is also supported by NDB Cluster.
SOURCE_COMPRESSION_ALGORITHMS
Specifies the permitted compression algorithms for
connections to the replication source server. The
available algorithms are the same as for the
protocol_compression_algorithms
system variable. The default value is
uncompressed
.
SOURCE_COMPRESSION_ALGORITHMS
is
available as of MySQL 8.0.18.
The value of
SOURCE_COMPRESSION_ALGORITHMS
applies
only if the
slave_compressed_protocol
system variable is disabled. If
slave_compressed_protocol
is enabled, it takes precedence over
SOURCE_COMPRESSION_ALGORITHMS
and
connections to the source use zlib
compression if both source and replica support that
algorithm. For more information, see
Section 4.2.8, “Connection Compression Control”.
Binary log transaction compression (available as of MySQL
8.0.20), which is activated by the
binlog_transaction_compression
system variable, can also be used to save bandwidth. If
you do this in combination with connection compression,
connection compression has less opportunity to act on the
data, but can still compress headers and those events and
transaction payloads that are uncompressed. For more
information on binary log transaction compression, see
Section 5.4.4.5, “Binary Log Transaction Compression”.
SOURCE_CONNECT_RETRY
Specifies the interval between the reconnection attempts
that the replica makes after the connection to the source
times out. The attempts are limited by the
SOURCE_RETRY_COUNT
option. If both the
default settings are used, the replica waits 60 seconds
between reconnection attempts
(SOURCE_CONNECT_RETRY=60
), and keeps
attempting to reconnect at this rate for 60 days
(SOURCE_RETRY_COUNT=86400
). These
values are recorded in the source metadata repository and
shown in the
replication_connection_configuration
Performance Schema table.
SOURCE_CONNECTION_AUTO_FAILOVER
Activates the asynchronous connection failover mechanism
for a replication channel if one or more alternative
replication source servers are available (so when there
are multiple MySQL servers or groups of servers that share
the replicated data).
SOURCE_CONNECTION_AUTO_FAILOVER
is
available as of MySQL 8.0.22. The asynchronous connection
failover mechanism takes over after the reconnection
attempts controlled by
SOURCE_CONNECT_RETRY
and
SOURCE_RETRY_COUNT
are exhausted. It
reconnects the replica to an alternative source chosen
from a specified source list, which you manage using the
asynchronous_connection_failover_add_source
and
asynchronous_connection_failover_delete_source
UDFs. To add and remove managed groups of servers, use the
asynchronous_connection_failover_add_managed
and
asynchronous_connection_failover_delete_managed
UDFs instead. For more information, see
Section 17.4.9, “Switching Sources with Asynchronous Connection Failover”.
You can only set
SOURCE_CONNECTION_AUTO_FAILOVER =
1
when GTID auto-positioning is in use
(SOURCE_AUTO_POSITION = 1
).
When you set
SOURCE_CONNECTION_AUTO_FAILOVER =
1
, set
SOURCE_RETRY_COUNT
and
SOURCE_CONNECT_RETRY
to minimal
numbers that just allow a few retry attempts with
the same source, in case the connection failure is
caused by a transient network outage. Otherwise the
asynchronous connection failover mechanism cannot be
activated promptly. Suitable values are
SOURCE_RETRY_COUNT=3
and
SOURCE_CONNECT_RETRY=10
, which
make the replica retry the connection 3 times with
10-second intervals between.
When you set
SOURCE_CONNECTION_AUTO_FAILOVER =
1
, the replication metadata repositories
must contain the credentials for a replication user
account that can be used to connect to all the
servers on the source list for the replication
channel. The account must also have
SELECT
permissions on the
Performance Schema tables. These credentials can be
set using the CHANGE
REPLICATION SOURCE TO
statement with the
SOURCE_USER
and
SOURCE_PASSWORD
options. For more
information, see
Section 17.4.9, “Switching Sources with Asynchronous Connection Failover”.
SOURCE_DELAY
Specifies how many seconds behind the source the replica
must lag. An event received from the source is not
executed until at least
interval
seconds later than its
execution on the source. The default is 0. An error occurs
if interval
is not a
nonnegative integer in the range from 0 to
231−1. For more
information, see
Section 17.4.11, “Delayed Replication”. A
CHANGE REPLICATION SOURCE TO
statement
using the SOURCE_DELAY
option can be
executed on a running replica when the replication SQL
thread is stopped.
SOURCE_HEARTBEAT_PERIOD
Controls the heartbeat interval, which stops the connection timeout occurring in the absence of data if the connection is still good. A heartbeat signal is sent to the replica after that number of seconds, and the waiting period is reset whenever the source's binary log is updated with an event. Heartbeats are therefore sent by the source only if there are no unsent events in the binary log file for a period longer than this.
The heartbeat interval interval
is a decimal value having the range 0 to 4294967 seconds
and a resolution in milliseconds; the smallest nonzero
value is 0.001. Setting
interval
to 0 disables
heartbeats altogether. The heartbeat interval defaults to
half the value of the
slave_net_timeout
system
variable. It is recorded in the source metadata repository
and shown in the
replication_connection_configuration
Performance Schema table. Issuing
RESET
REPLICA
resets the heartbeat interval to the
default value.
The slave_net_timeout
system variable specifies the number of seconds that the
replica waits for either more data or a heartbeat signal
from the source, before the replica considers the
connection broken, aborts the read, and tries to
reconnect. The default value is 60 seconds (one minute).
Note that a change to the value or default setting of
slave_net_timeout
does
not automatically change the heartbeat interval, whether
that has been set explicitly or is using a previously
calculated default. A warning is issued if you set
@@GLOBAL.slave_net_timeout
to a value
less than that of the current heartbeat interval. If
slave_net_timeout
is
changed, you must also issue CHANGE
REPLICATION SOURCE TO
to adjust the heartbeat
interval to an appropriate value so that the heartbeat
signal occurs before the connection timeout. If you do not
do this, the heartbeat signal has no effect, and if no
data is received from the source, the replica can make
repeated reconnection attempts, creating zombie dump
threads.
SOURCE_HOST
The host name or IP address of the replication source server. The replica uses this to connect to the source.
If you specify SOURCE_HOST
or
SOURCE_PORT
, the replica assumes that
the source server is different from before (even if the
option value is the same as its current value.) In this
case, the old values for the source's binary log file name
and position are considered no longer applicable, so if
you do not specify SOURCE_LOG_FILE
and
SOURCE_LOG_POS
in the statement,
SOURCE_LOG_FILE=''
and
SOURCE_LOG_POS=4
are silently appended
to it.
Setting SOURCE_HOST=''
(that is,
setting its value explicitly to an empty string) is
not the same as not setting
SOURCE_HOST
at all. Trying to set
SOURCE_HOST
to an empty string fails
with an error.
SOURCE_LOG_FILE
,
SOURCE_LOG_POS
The binary log file name, and the location in that file,
at which the replication I/O thread begins reading from
the source's binary log the next time the thread starts.
Specify these options if you are using binary log file
position based replication.
SOURCE_LOG_FILE
must include the
numeric suffix of a specific binary log file that is
available on the source server, for example,
SOURCE_LOG_FILE='binlog.000145'
.
SOURCE_LOG_POS
is the numeric position
for the replica to start reading in that file.
SOURCE_LOG_POS=4
represents the start
of the events in a binary log file.
If you specify either of
SOURCE_LOG_FILE
or
SOURCE_LOG_POS
, you cannot specify
RELAY_LOG_FILE
or
RELAY_LOG_POS
. If you specify either of
SOURCE_LOG_FILE
or
SOURCE_LOG_POS
, you also cannot specify
SOURCE_AUTO_POSITION = 1
, which is for
GTID-based replication.
If neither of SOURCE_LOG_FILE
or
SOURCE_LOG_POS
is specified, the
replica uses the last coordinates of the
replication SQL thread before
CHANGE REPLICATION SOURCE TO
was
issued. This ensures that there is no discontinuity in
replication, even if the replication SQL thread was late
compared to the replication I/O thread.
SOURCE_PASSWORD
The password for the replication user account to use for
connecting to the replication source server. If you
specify SOURCE_PASSWORD
,
SOURCE_USER
is also required.
The password used for a replication user account in a
CHANGE REPLICATION SOURCE TO
statement
is limited to 32 characters in length. Trying to use a
password of more than 32 characters causes CHANGE
REPLICATION SOURCE TO
to fail.
SOURCE_PORT
The TCP/IP port number that the replica uses to connect to the replication source server.
Replication cannot use Unix socket files. You must be able to connect to the replication source server using TCP/IP.
If you specify SOURCE_HOST
or
SOURCE_PORT
, the replica assumes that
the source server is different from before (even if the
option value is the same as its current value.) In this
case, the old values for the source's binary log file name
and position are considered no longer applicable, so if
you do not specify SOURCE_LOG_FILE
and
SOURCE_LOG_POS
in the statement,
SOURCE_LOG_FILE=''
and
SOURCE_LOG_POS=4
are silently appended
to it.
SOURCE_PUBLIC_KEY_PATH
Enables RSA key pair-based password exchange by providing
the path name to a file containing a replica-side copy of
the public key required by the source. The file must be in
PEM format. This option applies to replicas that
authenticate with the sha256_password
or caching_sha2_password
authentication
plugin. (For sha256_password
,
SOURCE_PUBLIC_KEY_PATH
can be used only
if MySQL was built using OpenSSL.) If you are using a
replication user account that authenticates with the
caching_sha2_password
plugin (which is
the default from MySQL 8.0), and you are not using a
secure connection, you must specify either this option or
the GET_SOURCE_PUBLIC_KEY=1
option to
provide the RSA public key to the replica.
SOURCE_RETRY_COUNT
Sets the maximum number of reconnection attempts that the
replica makes after the connection to the source times
out, as determined by the
slave_net_timeout
system
variable. If the replica does need to reconnect, the first
retry occurs immediately after the timeout. The interval
between the attempts is specified by the
SOURCE_CONNECT_RETRY
option. If both
the default settings are used, the replica waits 60
seconds between reconnection attempts
(SOURCE_CONNECT_RETRY=60
), and keeps
attempting to reconnect at this rate for 60 days
(SOURCE_RETRY_COUNT=86400
). These
values are recorded in the source metadata repository and
shown in the
replication_connection_configuration
Performance Schema table.
SOURCE_RETRY_COUNT
supersedes the
--master-retry-count
server
startup option.
SOURCE_SSL_xxx
,
SOURCE_TLS_xxx
Specify how the replica uses encryption and ciphers to
secure the replication connection. These options can be
changed even on replicas that are compiled without SSL
support. They are saved to the source metadata repository,
but are ignored if the replica does not have SSL support
enabled. The
SOURCE_SSL_
and
xxx
SOURCE_TLS_
options perform the same functions as the
xxx
--ssl-
and
xxx
--tls-
client options described in
Command Options for Encrypted Connections. The
correspondence between the two sets of options, and the
use of the
xxx
SOURCE_SSL_
and
xxx
SOURCE_TLS_
options to set up a secure connection, is explained in
Section 17.3.1, “Setting Up Replication to Use Encrypted Connections”.
xxx
SOURCE_USER
The user name for the replication user account to use for connecting to the replication source server.
To connect to the source using a replication user
account that authenticates with the
caching_sha2_password
plugin, you
must either set up a secure connection as described in
Section 17.3.1, “Setting Up Replication to Use Encrypted Connections”,
or enable the unencrypted connection to support password
exchange using an RSA key pair. The
caching_sha2_password
authentication
plugin is the default for new users created from MySQL
8.0 (for details, see
Section 6.4.1.2, “Caching SHA-2 Pluggable Authentication”).
If the user account that you create or use for
replication uses this authentication plugin, and you are
not using a secure connection, you must enable RSA key
pair-based password exchange for a successful
connection. You can do this using either the
SOURCE_PUBLIC_KEY_PATH
option or the
GET_SOURCE_PUBLIC_KEY=1
option for
this statement.
It is possible to set an empty user name by specifying
SOURCE_USER=''
, but the replication
channel cannot be started with an empty user name. In
releases before MySQL 8.0.21, only set an empty
SOURCE_USER
user name if you need to
clear previously used credentials from the replication
metadata repositories for security purposes. Do not use
the channel afterwards, due to a bug in these releases
that can substitute a default user name if an empty user
name is read from the repositories (for example, during an
automatic restart of a Group Replication channel). From
MySQL 8.0.21, it is valid to set an empty
SOURCE_USER
user name and use the
channel afterwards if you always provide user credentials
using the
START
REPLICA
statement or START
GROUP_REPLICATION
statement that starts the
replication channel. This approach means that the
replication channel always needs operator intervention to
restart, but the user credentials are not recorded in the
replication metadata repositories.
The text of a running CHANGE
REPLICATION SOURCE TO
statement, including
values for SOURCE_USER
and
SOURCE_PASSWORD
, can be seen in the
output of a concurrent SHOW
PROCESSLIST
statement. (The complete text of a
START
REPLICA
statement is also visible to
SHOW PROCESSLIST
.)
SOURCE_ZSTD_COMPRESSION_LEVEL
The compression level to use for connections to the
replication source server that use the
zstd
compression algorithm. The
permitted levels are from 1 to 22, with larger values
indicating increasing levels of compression. The default
zstd
compression level is 3. The
compression level setting has no effect on connections
that do not use zstd
compression.
SOURCE_ZSTD_COMPRESSION_LEVEL
is
available as of MySQL 8.0.18. For more information, see
Section 4.2.8, “Connection Compression Control”.
The following table shows the maximum permissible length for the string-valued options.
Option | Maximum Length |
---|---|
SOURCE_HOST |
255 |
SOURCE_USER |
96 |
SOURCE_PASSWORD |
32 |
SOURCE_LOG_FILE |
511 |
RELAY_LOG_FILE |
511 |
SOURCE_SSL_CA |
511 |
SOURCE_SSL_CAPATH |
511 |
SOURCE_SSL_CERT |
511 |
SOURCE_SSL_CRL |
511 |
SOURCE_SSL_CRLPATH |
511 |
SOURCE_SSL_KEY |
511 |
SOURCE_SSL_CIPHER |
511 |
SOURCE_TLS_VERSION |
511 |
SOURCE_TLS_CIPHERSUITES |
4000 |
SOURCE_PUBLIC_KEY_PATH |
511 |
SOURCE_COMPRESSION_ALGORITHMS |
99 |
NETWORK_NAMESPACE |
64 |