WL#5564: Replication Information: scope, visibility, persistency, mutability

Affects: Server-Prototype Only   —   Status: Assigned   —   Priority: Medium

==== Purpose ====

This worklog aims to ensure that the replication interface that we
expose to the user is consistent and future-proof. (Here, the term
"consistent" does not refer to database consistency, but to interface
consistency. I.e., the interface should use unified naming conventions
where possible, map well to a structured mental view of the data,
avoid unnecessary duplication, etc.)

We will analyze all pieces of information and determine a unified way
to organize it. This may affect the design of the worklogs listed in
B2.

This worklog will not have any associated code. It will only serve as
a base to design other worklogs.

==== Background ====

B1. Replication-related information is currently user-accessible in the
    following ways:
     - As server system variables.
     - As server status variables.
     - As server command-line options.
     - In SHOW SLAVE STATUS.
     - In SHOW MASTER STATUS.
     - In CHANGE MASTER.
     - In arguments to START SLAVE.
     - In SHOW SLAVE HOSTS.

B2. In the current implementation, it is easy to distinguish several
    independent scopes of replication-related information: information may
    be associated with the IO thread, the SQL thread, the sequence of relay
    logs, a dump thread, the sequence of binary logs, a client, or be global.

    However, currently, commands like CHANGE MASTER, SHOW SLAVE STATUS,
    SHOW MASTER STATUS, and SHOW SLAVE HOSTS unnecessarily couple information
    from different scopes in a way that assumes there is one IO thread, one SQL
    thread, one sequence of relay logs, and one sequence of binlogs.

    It would be better if the different scopes were separated entirely. This
    would have several advantages:
     - It would make clear which scope each field belongs to. For example,
       it cannot currently be deduced from the way the field is exposed if
       Replicate_Ignore_Server_Ids affects the IO thread or the SQL thread
       (both are conceivable). If this could be deduced from the scope, the
       user interface would be more easy to understand.
     - The current schema design of SHOW SLAVE STATUS has insertion anomalities
(http://en.wikipedia.org/wiki/Database_normalization#Free_the_database_of_modification_anomalies)
       For example, we currently expose fields of the IO thread when no IO
       thread is configured. When we separate scopes, we don't have to expose
       dummy fields with default values.
     - In the future, we may change the model for replication so that there
       can be more than one SQL thread, more than one IO thread, more than one
       sequence of relay logs, and more than one binary log. Existing plans
       include WL#1697, which will allow more than one IO thread and more than
       one sequence of relay logs; and http://lists.mysql.com/internals/38079,
       which suggests more than one sequence of binary logs. When we separate
       scopes, we also open the door for other similar ideas; for instance,
       if we want to allow similar filtering as suggested at
       http://lists.mysql.com/internals/38079, but on the slave side, it means
       we need more relay logs and SQL threads than IO threads.

B3. There is ongoing work that changes how fields are made persistent or
    visible:
     - WL#3656 exposes information that is currently visible in
       SHOW SLAVE STATUS in a PERFORMANCE_SCHEMA table.
     - WL#3657 exposes information that is currently visible in
       SHOW MASTER STATUS in a PERFORMANCE_SCHEMA table.
     - WL#5177 makes replication filters persistent and exposes them in a
       new way, using system tables in the mysql database.
     - WL#2775 makes information that is currently stored in master.info
       or relay-log.info persistent and visible, using system tables in
       the mysql database.

B4. There is no clear rule for things like:
     - What is made persistent and not.
       For example, Replicate_Ignore_Server_Ids and --replicate-same-server-id
       both filter events by server id, but only the former is persistent.
     - What is mutable and not.
       For example, both --slave-skip-errors and slave_exec_mode affect how
       the SQL thread handles various kinds of errors, but only the latter is
       settable after startup.
     - What is mutable where.
       For example, CHANGE MASTER TO RELAY_LOG_POS,
       SET @@global.sql_skip_counter, and START SLAVE UNTIL RELAY_LOG_POS all
       specify where the SQL thread will start to execute, but they use
       three different types of syntax.
     - What is exposed and not.
       For example, both the slave's and the master's coordinates for both the
       IO thread and the SQL thread are visible, *except* the slaves's
       coordinates for the IO thread.
     - What is exposed where.
       For example, both MASTER_HEARTBEAT_PERIOD and MASTER_CONNECT_RETRY are
       parameters of the IO thread (and both are settable with CHANGE MASTER),
       but the former is readable as a status variable and the latter is
       readable in SHOW SLAVE STATUS.
     - What names do we use.
       For example, the position of the SQL thread in master coordinates is
       expressed by the two fields Relay_Master_Log_File and
       Exec_Master_Log_Pos, each of which seems to use its own naming
       convention.
    These are just examples, and there are more examples. The point here is that
    we need to make up clear rules in order to create a consistent interface.

B5. The naming of some replication options are ambiguous. For example the 
    following SSL related options in CHANGE MASTER TO:

    | MASTER_SSL = {0|1}
    | MASTER_SSL_CA = 'ca_file_name'
    | MASTER_SSL_CAPATH = 'ca_directory_name'
    | MASTER_SSL_CERT = 'cert_file_name'
    | MASTER_SSL_KEY = 'key_file_name'
    | MASTER_SSL_CIPHER = 'cipher_list'
    | MASTER_SSL_VERIFY_SERVER_CERT = {0|1}

    The phrase "MASTER" is badly misleading. If fact most of those 
    variables are for the *slave* side of the replication channel, not 
    the master side (as the naming suggests) (quote from BUG#11759446).


==== Definitions and Scope of this Worklog ====

We use the term "field" to denote one piece of information with a defined
semantics. For example, the file name of the relay log that the SQL thread is
currently reading from is one field; the slave_exec_mode is another field.

This worklog deals with fields that relate to the replication master and to the
replication slave but not to the contents of the binary logs or relay logs
(i.e., not the output of SHOW BINLOG EVENTS or SHOW RELAY_LOG EVENTS). Fields
are found in the following places:

 - SHOW SLAVE STATUS
   http://dev.mysql.com/doc/refman/5.5/en/show-slave-status.html
 - Slave command line options
   http://dev.mysql.com/doc/refman/5.5/en/replication-options-slave.html
 - Slave system variables
   http://dev.mysql.com/doc/refman/5.5/en/replication-options-slave.html
 - Server status variables
   http://dev.mysql.com/doc/refman/5.5/en/server-status-variables.html
   TODO: not yet accounted for in table
 - Fields settable with CHANGE MASTER
   http://dev.mysql.com/doc/refman/5.5/en/change-master-to.html
 - Fields settable when executing START SLAVE
   http://dev.mysql.com/doc/refman/5.5/en/start-slave.html
 - SHOW MASTER STATUS
   http://dev.mysql.com/doc/refman/5.5/en/show-master-status.html
 - SHOW SLAVE HOSTS
   http://dev.mysql.com/doc/refman/5.5/en/show-slave-hosts.html
 - Master command line options and system variables
   http://dev.mysql.com/doc/refman/5.5/en/replication-options-master.html
 - Binlog command line options and variables
   http://dev.mysql.com/doc/refman/5.5/en/replication-options-binary-log.html
 - Fields currently not exposed

Some fields appear in more than one place.


==== Step-by-step Plan ====

We will do this WL in the following steps:

S1. List all fields that are currently exposed to end users, or that we
    plan to expose in the near future.

S2. For each field, determine:
    S2.1 The logical scope.
         Is the field relevant for each IO thread, for each SQL thread, for
         each sequence of relay logs, for each sequence of binary logs, for
         each dump thread, for each client, or globally?
    S2.2 The current visibility.
         Where is the field currently exposed?
    S2.3 The current persistency.
         Is the field currently made persistent?
    S2.4 The current mutability.
         Is it currently possible to change the field? When and under what
         conditions can it be changed?

S3. For each field, determine:
    S3.1 If the field should be made persistent in the future.
    S3.2 If and when the field should be made mutable in the future.
    S3.3 If the field should be made visible in the future.
    S3.4 What is an appropriate name for the field.

S4. Determine how fields should be grouped together and how to expose them to
    users. For example, some fields may be exposed in system tables, some
    fields may be exposed as variables, some fields may be exposed in
    INFORMATION_SCHEMA or PERFORMANCE_SCHEMA tables, and we may propose new
    ways to modify fields so that their logical scope is taken into account.

S5. Ensure that all relevant worklogs are updated to conform with the design
    in S4.

S6. Possibly file new worklogs if the existing ones are not enough.


==== Notes on deprecated fields ====

Fields that are deprecated and completely removed do not need to be analyzed.
The following worklogs list deprecated features:

 WL#5154
 WL#5182
 WL#5185
 WL#5265
 WL#5533

However, after analyzing these worklogs I found that none of the fields has been
deprecated and completely removed. A small number fields were exposed in two
places (like --master-retry-count / CHANGE MASTER TO MASTER_RETRY_COUNT), one of
which has been removed; but all fields remain in the server.
==== Data Model and Field Scopes ====

We assume a model where the following scopes are possible:

 - One server with global-scope fields.

 - Zero or more sequences of binlogs with binlog-scope fields.

   In the future, we may want to have multiple parallel binlogs; e.g.,
   one binlog for each database.  That would allow easy migration of
   one database out of many from one server to another.  See
   http://lists.mysql.com/internals/38079

 - Zero or more dump threads with dump-scope fields.

 - Zero or more clients with client-scope fields.

 - Zero or more sequences of relay logs with relay log-scope fields.

   In the future, we may want to be able to replicate from multiple
   masters or using multiple connections to the same master.

 - Zero or more IO threads with IO thread scope, each writing to one
   or more sequences of relay logs.

   In the future, there may be more than one IO thread (because we want to 
support
   replication from more than one master, WL#1697), and possibly each IO thread
   may write to more than one sequence of relay logs (e.g., to split the relay
   log by database to allow more efficient parallel execution of relay logs), 
and
   possibly more than one IO thread writes to each relay log.

 - Each sequence of relay logs is associated with zero or more SQL threads with 
SQL
   thread scope.

   In the future, there may be multiple parallel threads that apply events from 
the
   relay logs.  See WL#5563.

This model is more general than what the server currently supports.
In particular, the server is currently limited to one binlog, one
sequence of relay logs, one IO thread, and one SQL thread.


==== Interfaces for Storing, Modifying, and Exposing Fields ====

Fields that are persistent need to be stored somewhere.  Fields that
can be modified need a way to be updated.  Fields that are visible
need a way to access them.

We will separate the concepts of storage, modification, and visibility
of fields into three different interfaces.  Moreover, global fields
that merely serve as default values for other fields are in a fourth
interface (namely, they are exposed as server variables).  This
separation allows, for instance, all mutable fields to be modified
with similar interfaces, independently of whether the fields are
persistent or not.  We will define the following types of interfaces:

 - Persistent fields are stored in tables in the mysql database.

 - Mutable fields have a dedicated statement syntax to modify them.

 - Visible fields are listed in a view in a PERFORMANCE_SCHEMA table.

 - If a field is specific to one scope but has a global default value,
   then the global default value is settable and gettable using a
   @@global.variable.

The following tables are used for persistent storage:

  mysql.io_thread - persistent storage of fields with IO thread scope
  mysql.sql_thread - persistent storage of fields with SQL thread scope
  mysql.relay_log - persistent storage of fields with relay log scope
  mysql.dump_thread - persistent storage of fields with dump thread scope
  mysql.binlog - persistent storage of fields with binlog scope

The following views are used to access fields that should be readable
(here, P_S is an abbreviation for PERFORMANCE_SCHEMA):

  P_S.IO_THREAD - read-only view of fields with IO thread scope
  P_S.SQL_THREAD - read-only view of fields with SQL thread scope
  P_S.RELAY_LOG - read-only view of fields with relay log scope
  P_S.DUMP_THREAD - read-only view of fields with dump thread scope
  P_S.BINLOG - read-only view of fields with binlog scope

The following commands are used to set fields that should be settable.

  CHANGE IO_THREAD <ID> TO <FIELD> = <VALUE>
    Set a new value for a field of a named IO thread
  CHANGE SQL_THREAD <ID> TO <FIELD> = <VALUE>
    Set a new value for a field of a named SQL thread
  CHANGE RELAY_LOG <ID> TO <FIELD> = <VALUE>
    Set a new value for a field of a named sequence of relay logs
  CHANGE DUMP_THREAD <ID> TO <FIELD> = <VALUE>
    Set a new value for a field of a named dump thread
  CHANGE BINLOG <ID> TO <FIELD> = <VALUE>
    Set a new value for a field of a named sequence of binary logs

Here, <ID> identifies the object among all objects (e.g., identifies one out of
many IO threads). The form of <ID> (string, number, etc) can be determined in
later worklogs. In the present worklog, we only determine which fields that
should be settable by which command.


==== Names ====

When fields are added to new places, we should use consistent naming
schemes.  We should ensure the following:

 - Fields should use the same name in all places where they are added.
   This is relevant for fields that are added in two or more of "the
   mysql database", "the P_S database", and "the CHANGE command".

   For example, in the current interface, the read position of the IO
   thread in the master's coordinates is called Read_Master_Log_Pos in
   SHOW SLAVE STATUS and Master_Log_Pos in CHANGE MASTER. We should
   take the opportunity to fix such inconsistencies in the new interface.

 - Fields should not use unnecessary prefixes.  For example, if a
   field has SQL thread scope, then it will normally be accessed
   through a table or command that contains the word SQL_THREAD, so
   there is no need to prefix the field with SQL_.  When fields have
   default values that are stored in global or session variables, then those
   variables need to be prefixed with the scope.

   For example, when we add the field that is currently called
   SQL_Delay as a column in P_S.SQL_THREAD, it should be called Delay,
   and the CHANGE command should be CHANGE SQL_THREAD <IDENT> TO DELAY
   = VALUE.  However, the global variable that holds the default delay
   for new SQL threads should be called @@global.sql_thread_delay.
   Similarly, the words Master, Slave, and Replicate are superfluous
   in most places.

 - Similar fields should have similar naming conventions.

   For example, most fields that are limitations are prefixed with the
   word max. So instead of relay-log-space-limit, we should use a name
   that begins with max, and in of binlog-row-event-max-size, we
   should move the word max to the beginning.

 - Names that are known to cause confusion should be clarified.

   For example, binlog_format causes a lot of confusion because it
   specifies a policy, not a format. (There are two formats: row and
   statement. There are three policies: use only row format (that's
   the row policy), use only statement (that's the statement policy),
   or use whatever is most appropriate (that's the mixed policy)). So
   we should rename it to Policy.

 - Non-standard or ambiguous abbreviations should be avoided.

   For example, we should use Position instead of Pos, and
   Report_Authentication_Info instead of Report_Auth_Info (Auth can be
   confused with the related term Authorization).  More standard
   abbreviations like db, id, init, max, SSL, sync, and UUID should of
   course be used.

 - Use standardized schemas for Capitalization.  It seems that column
   names for SHOW statements have all sorts of capitalization (all of
   Leading_capital_with_underscores, Camel_Case_With_Underscores,
   Leading capital with spaces, Camel Case With Spaces),
   Leading_capital_with_underscores is most common for column names in
   the mysql database (lower_case_with_underscores appears too),
   UPPER_CASE_WITH_UNDERSCORE is most common for column names in the
   PERFORMANCE_SCHEMA and INFORMATION_SCHEMA databases
   (lower_case_with_underscores appear too in INFORMATION_SCHEMA),
   --lower-case-with-dashes is the most common for command line
   arguments, lower_case_with_underscores is most common for variable
   names, UPPER_CASE_WITH_UNDERSCORES is most common for sql
   statements, Leading_capital_with_underscores is most common for
   status variables, and UPPER_CASE_WITH_UNDERSCORES is most common
   for table names in the PERFORMANCE_SCHEMA database.

   So we use Leading_capital_with_underscores for column names in SHOW
   statements and in the mysql database, UPPER_CASE_WITH_UNDERSCORE
   for column names in INFORMATION_SCHEMA and PERFORMANCE_SCHEMA,
   --lower-case-with-dashes for command line arguments,
   lower_case_with_underscores for variables names,
   UPPER_CASE_WITH_UNDERSCORES for SQL statements,
   Leading_capital_with_underscores for status variables.

 - Question: the words "IO thread" and "SQL thread" are a bit vague
   (e.g., most other threads do some IO; most client threads do some SQL,
   and the SQL thread executes row events that are not SQL).  Perhaps
   "copy thread" and "apply thread" are more descriptive.  Can we use
   these names (or something better) or should we stick to existing names?


==== Backward compatibility ====

There are no backward compatibility issues because this WL only
defines new interfaces, it does not change existing interfaces.

In the future (in other worklogs) we may make e.g. SHOW SLAVE STATUS
and CHANGE MASTER throw an error whenever there is more than one SQL
thread, more than one IO thread, or more than one sequence of relay
logs.  This again does not break backward compatibility because it has
not been possible to use more than one of each object before.


==== Classification of Fields ====

In the following table, we analyze all fields.


---- Legend ----

FIELD: The current name of the field. Names are grouped by the place
     they are found.  Fields are found in the following places:

       SHOW SLAVE STATUS
       Slave command line options
       Slave variables
       Fields settable with CHANGE MASTER
       Fields settable when executing START SLAVE
       SHOW MASTER STATUS
       SHOW SLAVE HOSTS
       Master command line options and variables
       Binlog command line options and variables
       Fields currently not exposed

     To make the analysis clear, fields that appear on two places are only
     analyzed in one place. The other place contains a reference to
     the first place (for an example, see the line Master_Host in the
     SHOW SLAVE STATUS section of the table).

SCP: The logical scope of the field. For purposes of classification, we assume
     a more general model of replication slaves and masters than is currently
     implemented. Currently, there is one sequence of relay logs,
     one IO thread and one SQL thread. In the future, as a consequence of
     implementing multi-threaded slave and multi-master replication, we may
     have several sequences of relay logs, each of which is associated with
     several IO threads and several SQL threads. Moreover, currently there is
     only one binlog, but in the future we may use several binlogs (and, e.g.,
     filter events into different binlogs depending on database etc).
     Hence, fields can have the following logical scopes:
     I - the field is relevant for each IO thread
     S - the field is relevant for each SQL thread
     R - the field is relevant for each sequence of relay logs
     D - the field is relevant for each dump thread
     B - the field is relevant for each binlog
     G - the field is relevant globally
     IG - the field is relevant for each IO thread but can have a global default
     SG - the field is relevant for each SQL thread but can have a global 
default
     RG - the field is relevant for each sequence of relay logs but can have a
          global default
     DG - the field is relevant for each dump but can have a global default
     BG - the field is relevant for each binlog but can have a global default
     CG - the field is relevant for each client thread but can have a global 
default
     BCG - the field is relevant for each binlog, but each client can have its 
own
           set of values and there can be a global default set of values

CURRENT/PER: the persistence of the field, currently.
     Y - The field is currently persistent.
     - - The field is not currently persistsent.

CURRENT/SET: when can a user set the field's value, currently.
     Y - The field can be set at any time
     !I - The field can be set when the IO thread is stopped
     !S - The field can be set when the SQL thread is stopped
     !R - The field can be set when all IO threads that read from the relevant 
relay
          log are stopped.
     !IS - The field can be set when both the IO and the SQL thread is stopped
     !T - The field can be set globally always, but in the client only when 
there is
          no ongoing transaction
     X - The field can be set by exiting and restarting the server
     - - The field is not currently mutable.

CURRENT/VIS: where the field is currently visible.
     S - The field exists in SHOW SLAVE STATUS.
     M - The field exists in SHOW MASTER STATUS.
     H - The field exists in SHOW SLAVE HOSTS.
     V - The field exists as a global variable.
     t - The field exists as a global sTatus variable
     - - The field is currently not exposed.
     
WANTED/PER: the persistence of the field, as we would like it to be.
     Y - The field should be persistent: i.e., it should be stored in
         a table in the mysql database. The SCP column determines which table.
     - - The field shouuld not be persistsent.

WANTED/SET: when can the user set the field's value, as we would like it to be.
     Y - The field can be set at any time. The scope determines how the field
         can be set: using a variable if the scope contains 'G'; using
         CHANGE [IO_THREAD|SQL_THREAD|DUMP_THREAD|RELAY_LOG|BINLOG]
         if the scope contains I/S/D/R/B.
     !I - The field can be set when the IO thread is stopped, using
          CHANGE IO_THREAD.
     !S - The field can be set when the SQL thread is stopped, using
          CHANGE SQL_THREAD.
     !R - The field can be set when all IO threads that read from the relevant 
relay
          log are stopped, using CHANGE RELAY_LOG.
     !T - The field can be set globally always, but in the client only when 
there is
          no ongoing transaction, using CHANGE BINLOG
     X - The field can only be set by exiting and restarting the server, using
         --field-name-in-lowercase-with-underscores-replaced-by-dashes=value
     - - The field is not currently mutable.

WANTED/VIS: places where we may want to add the field in the
     future (for backward compatibility, we cannot remove existing fields).
     Can be one or more of:
     Y - The field should be visible
     - - The field should not be visible

WANTED/NAME: the name we would like to use when adding the field to
     new places (listed in WANTED/VIS), or empty if we want to keep
     the old name.


---- Classification ----

================================================================================
                            |   ||  CURRENT  ||  WANTED                        |
FIELD                       |SCP||PER|SET|VIS||PER|SET|VIS|NAME                |
================================================================================
SHOW SLAVE STATUS ----------+---++---+---+---++---+---+---+--------------------+
             Slave_IO_State | I || - | - | S || - | - | Y |Run_State           |
                Master_Host = CHANGE MASTER TO MASTER_HOST
                Master_User = CHANGE MASTER TO MASTER_USER
                Master_Port = CHANGE MASTER TO MASTER_PORT
              Connect_Retry = CHANGE MASTER TO MASTER_CONNECT_RETRY
            Master_Log_File | I || Y | - | S || Y |!I | Y |File_Master         |
        Read_Master_Log_Pos | I || Y | - | S || Y |!I | Y |Position_Master     |
             Relay_Log_File | S || Y |!IS| S || Y |!S | Y |File_Slave          |
              Relay_Log_Pos | S || Y |!IS| S || Y |!S | Y |Position_Slave      |
      Relay_Master_Log_File | S || Y |!IS| S || Y |!S | Y |File_Master         |
           Slave_IO_Running | I || - | - | S || Y | - | Y |Thread_Running (1)  |
          Slave_SQL_Running | S || - | - | S || Y | - | Y |Thread_Running (1)  |
            Replicate_Do_DB = replicate-do-db
        Replicate_Ignore_DB = replicate-ignore-db
         Replicate_Do_Table = replicate-do-table
     Replicate_Ignore_Table = replicate-ignore-table
    Replicate_Wild_Do_Table = replicate-wild-do-table
Replicate_Wild_Ignore_Table = replicate-wild-ignore-table
                 Last_Errno = SHOW SLAVE STATUS/Last_SQL_Errno
                 Last_Error = SHOW SLAVE STATUS/Last_SQL_Error
               Skip_Counter = sql_slave_skip_counter
        Exec_Master_Log_Pos | S || Y |!IS| S || Y |!S | Y |Position_Master     |
            Relay_Log_Space | R || - | - | S || - | - | Y |Disk_Usage          |
            Until_Condition | S || - |!IS| S || - | - | - |                    |
             Until_Log_File = START SLAVE/UNTIL [MASTER|RELAY]_LOG_FILE
              Until_Log_Pos = START SLAVE/UNTIL [MASTER|RELAY]_LOG_POS
         Master_SSL_Allowed | IG|| Y |!IS| S || Y |!I | Y |SSL_Allowed         |
         Master_SSL_CA_File | IG|| Y |!IS| S || Y |!I | Y |SSL_CA_File         |
         Master_SSL_CA_Path | IG|| Y |!IS| S || Y |!I | Y |SSL_CA_Path         |
            Master_SSL_Cert | IG|| Y |!IS| S || Y |!I | Y |SSL_Certificate     |
          Master_SSL_Cipher | IG|| Y |!IS| S || Y |!I | Y |SSL_Cipher          |
             Master_SSL_Key | IG|| Y |!IS| S || Y |!I | Y |SSL_Key             |
      Seconds_Behind_Master | I || - | - | S || - | - | Y |(2)                 |
Master_SSL_Verify_Server_Cer| IG|| Y |!IS| S || Y |!I | Y |SSL_Verify_Server_C-|
                            |   ||   |   |   ||   |   |   |ertificate          |
              Last_IO_Errno | I || - |!IS| S || Y | Y | Y |Last_Errno          |
              Last_IO_Error | I || - |!IS| S || Y | Y | Y |Last_Error          |
             Last_SQL_Errno | S || - |!IS| S || Y | Y | Y |Last_Errno          |
             Last_SQL_Error | S || - |!IS| S || Y | Y | Y |Last_Error          |
Replicate_Ignore_Server_Ids | IG|| Y |!IS| S || Y |!I | Y |Ignore_Server_Ids   |
           Master_Server_Id | I || - | - | S || - | - | Y |                    |
                Master_UUID | I || Y | - | S || Y | - | Y |                    |
           Master_Info_File = Slave command line options/master-info-file
                  SQL_Delay | SG|| Y |!IS| S || Y |!S | Y |Delay               |
        SQL_Remaining_Delay | S || - | - | S || - | - | Y |Remaining_Delay     |
    Slave_SQL_Running_State | S || - | - | S || - | - | Y |Run_State           |
Slave command line options -+---++---+---+---++---+---+---+--------------------+
    abort-slave-event-count | SG|| - | X | - || - |!S | Y |Abort_Event_Count   |
disconnect-slave-event-count| IG|| - | X | - || - |!I | Y |Disconnect_Event_Co-|
                            |   ||   |   |   ||   |   |   |unt                 |
          log-slave-updates | SG|| - | X | - || Y |!S | Y |Log_Updates         |
  log-slow-slave-statements | SG|| - | X | - || Y |!S | Y |Log_Slow_Statements |
               log-warnings | Not specific to replication
           master-info-file | I || - | X | S || - | - | - |                    |
         master-retry-count = CHANGE MASTER TO MASTER_CONNECT_RETRY
         max-relay-log-size | RG|| - | X | - || Y |!R | Y |Max_File_Size       |
                  read-only | G || - | X | - || Y | Y | Y |                    |
                  relay-log | R || - | X | - || Y |!R | Y |File_Basename       |
            relay-log-index | R || - | X | - || Y |!R | Y |Index_File          |
        relay-log-info-file | S || - | X | - || - | - | - |                    |
            relay-log-purge | RG|| - | X | - || Y | Y | Y |Automatic_Purge     |
         relay-log-recovery | RG|| - | X | - || - | X | Y |Recovery            |
      relay-log-space-limit | RG|| - | X | S || Y |!R | Y |Max_Disk_Usage      |
            replicate-do-db | SG|| - | X | S || Y |!S | Y |Do_DB               |
        replicate-ignore-db | SG|| - | X | S || Y |!S | Y |Ignore_DB           |
         replicate-do-table | SG|| - | X | S || Y |!S | Y |Do_Table            |
     replicate-ignore-table | SG|| - | X | S || Y |!S | Y |Ignore_Table        |
       replicate-rewrite-db | SG|| - | X | - || Y |!S | Y |Rewrite_DB          |
   replicate-same-server-id | IG|| - | X | - || Y |!I | Y |Do_Same_Server_Id   |
    replicate-wild-do-table | SG|| - | X | S || Y |!S | Y |Wildcard_Do_Table   |
replicate-wild-ignore-table | SG|| - | X | S || Y |!S | Y |Wildcard_Ignore_Tab-|
                            |   ||   |   |   ||   |   |   |le                  |
                report-host | IG|| - | X | - || Y |!I | Y |                    |
            report-password | IG|| - | X | - || Y |!I | Y |                    |
                report-port | IG|| - | X | - || Y |!I | Y |                    |
                report-user | IG|| - | X | - || Y |!I | Y |                    |
       show-slave-auth-info | IG|| - | X | - || Y |!I | Y |Report_Authenticati-|
                            |   ||   |   |   ||   |   |   |on_Info             |
           skip-slave-start | G || - | X | - || - | X | Y |(1)                 |
  slave-compressed-protocol | IG|| - | X | - || Y |!I | Y |Compressed_Protocol |
          slave-load-tmpdir | SG|| - | X | - || Y |!S | Y |Load_Tmpdir         |
          slave-net-timeout | IG|| - | X | - || Y |!I | Y |Net_Timeout         |
          slave-skip-errors | SG|| - | X | - || Y |!S | Y |Skip_Errors         |
Slave variables ------------+---++---+---+---++---+---+---+--------------------+
                 init_slave | SG|| - | G | V || Y |!S | Y |Init_Statement      |
         relay_log_recovery = relay-log-recovery
  slave_compressed_protocol = slave-compressed-protocol
            slave_exec_mode | SG|| - | Y | V || Y |!S | Y |Execution_Mode      |
          slave_load_tmpdir = slave-load-tmpdir
          slave_net_timeout = slave-net-timeout
          slave_skip_errors = slave-skip-errors
  slave_transaction_retries | SG|| - | Y | V || Y |!S | Y |Transaction_Retry_C-|
                            |   ||   |   |   ||   |   |   |ount                |
     slave_type_conversions | SG|| - | Y | V || Y |!S | Y |Type_Conversions    |
     sql_slave_skip_counter | S || - |!S | SV|| Y |!S | Y |Skip_Count (1)      |
           sync_master_info | IG|| - | Y | V || - | - | - |                    |
             sync_relay_log | RG|| - | Y | V || Y |!I | Y |Sync_Frequency      |
        sync_relay_log_info | SG|| - | Y | V || - | - | - |                    |
CHANGE MASTER fields -------+---++---+---+---++---+---+---+--------------------+
                MASTER_BIND | I || Y |!IS| - || Y |!I | Y |Network_Interface   |
                MASTER_HOST | I || Y |!IS| - || Y |!I | Y |Host                |
                MASTER_USER | I || Y |!IS| - || Y |!I | Y |User                |
            MASTER_PASSWORD | I || Y |!IS| - || Y |!I | Y |Password            |
                MASTER_PORT | I || Y |!IS| - || Y |!I | Y |Port                |
       MASTER_CONNECT_RETRY | IG|| Y |!IS| - || Y |!I | Y |Connection_Retry_Co-|
                            |   ||   |   |   ||   |   |   |unt                 |
    MASTER_HEARTBEAT_PERIOD | IG|| Y |!IS| t || Y |!I | Y |Heartbeat_Period    |
            MASTER_LOG_FILE = SHOW SLAVE STATUS/Master_Log_File
             MASTER_LOG_POS = SHOW SLAVE STATUS/Master_Log_Pos
             RELAY_LOG_FILE = SHOW SLAVE STATUS/Relay_Log_File
              RELAY_LOG_POS = SHOW SLAVE STATUS/Relay_Log_Pos
                 MASTER_SSL = SHOW SLAVE STATUS/MASTER_SSL_ALLOWED
              MASTER_SSL_CA = SHOW SLAVE STATUS/MASTER_SSL_CA
          MASTER_SSL_CAPATH = SHOW SLAVE STATUS/MASTER_SSL_CAPATH
            MASTER_SSL_CERT = SHOW SLAVE STATUS/MASTER_SSL_CERT
             MASTER_SSL_KEY = SHOW SLAVE STATUS/MASTER_SSL_KEY
          MASTER_SSL_CIPHER = SHOW SLAVE STATUS/MASTER_SSL_CIPHER
MASTER_SSL_VERIFY_SERVER_CER= SHOW SLAVE STATUS/MASTER_SSL_VERIFY_SERVER_CERT
          IGNORE_SERVER_IDS = SHOW SLAVE STATUS/Replicate_Ignore_Server_Ids
START SLAVE fields ---------+---++---+---+---++---+---+---+--------------------+
      UNTIL MASTER_LOG_FILE | S || - |!S | S || Y |!S | Y |Until_File_Master   |
       UNTIL MASTER_LOG_POS | S || - |!S | S || Y |!S | Y |Until_Position_Mast-|
                            |   ||   |   |   ||   |   |   |er                  |
       UNTIL RELAY_LOG_FILE | S || - |!S | S || Y |!S | Y |Until_File_Slave    |
        UNTIL RELAY_LOG_POS | S || - |!S | S || Y |!S | Y |Until_Position_Slave|
SHOW MASTER STATUS ---------+---++---+---+---++---+---+---+--------------------+
                       File | D || - | - | M || - | - | Y |                    |
                   Position | D || - | - | M || - | - | Y |                    |
               Binlog_Do_DB = binlog-do-db
           Binlog_Ignore_DB = binlog-ignore-db
SHOW SLAVE HOSTS -----------+---++---+---+---++---+---+---+--------------------+
                  Server_id | D || - | - | H || - | - | Y |Server_Id           |
                       Host | D || - | - | H || - | - | Y |                    |
                       Port | D || - | - | H || - | - | Y |                    |
                  Master_id = Master variables/server_id
                 Slave_UUID | D || - | - | H || - | - | Y |UUID                |
Master variables and options+---++---+---+---++---+---+---+--------------------+
   auto_increment_increment | CG|| - | Y | V || Y | Y | Y |                    |
      auto_increment_offset | CG|| - | Y | V || Y | Y | Y |                    |
                  server_id | CG|| - | Y | V || Y | - | Y |                    |
Binlog options and variables+---++---+---+---++---+---+---+--------------------+
  binlog-row-event-max-size |BCG|| - | X | - || Y | Y | Y |Max_Row_Event_Size  |
                    log-bin | B || - | X | - || Y | Y | Y |File_Basename       |
              log-bin-index | B || - | X | - || Y | Y | Y |Index_File          |
log-bin-trust-function-creat= log_bin_trust_function_creators
               binlog-do-db |BCG|| - | X | M || Y | Y | Y |Do_DB               |
           binlog-ignore-db |BCG|| - | X | M || Y | Y | Y |Ignore_DB           |
     max-binlog-dump-events | DG|| - | X | - || - | Y | Y |Max_Events          |
 sporadic-binlog-dump-fail  | DG|| - | X | - || - | Y | Y |Sporadic_Failures   |
          binlog-cache-size = binlog_cache_size
          binlog_cache_size | BG|| - | Y | V || Y | Y | Y |Default_Cache_Size  |
binlog-direct-non-transactio= binlog_direct_non_transactional_updates
binlog_direct_non_transactio|BCG|| - |!T | V || Y |!T | Y |Write_Non_Transacti-|
                            |   ||   |   |   ||   |   |   |onal_Updates_Direct-|
                            |   ||   |   |   ||   |   |   |ly                  |
              binlog-format = binlog-format
              binlog_format |BCG|| - |!T | V || Y |!T | Y |Policy              |
      max-binlog-cache-size = max_binlog_cache_size
      max_binlog_cache_size | BG|| - | Y | V || Y | Y | Y |Max_Cache_Size      |
            max-binlog-size = max_binlog_size
            max_binlog_size | BG|| - | Y | V || Y | Y | Y |Max_File_Size       |
                    log_bin = sql_log_bin
                sql_log_bin |BCG|| - |!T | V || Y |!T | Y |Enabled             |
log_bin_trust_function_creat| G || - | Y | V || Y | Y | Y |Binlog_Trust_Functi-|
                            |   ||   |   |   ||   |   |   |on_Creators         |
            expire_log_days | B || - | Y | V || Y | Y | Y |Automatic_Purge_Del-|
                            |   ||   |   |   ||   |   |   |ay                  |
Server status variables ----+---++---+---+---++---+---+---+--------------------+
(here, "RSSM/RSSS" abbreviates "Rpl_semi_sync_master"/"Rpl_semi_sync_slave")
      Binlog_cache_disk_use | C || - | - | t || - | - | Y |Transaction_Cache_D-|
                            |   ||   |   |   ||   |   |   |isk_Use_Count       |
           Binlog_cache_use | C || - | - | t || - | - | Y |Transaction_Cache_U-|
                            |   ||   |   |   ||   |   |   |se_Count            |
               RSSM_clients | G || - | - | t || - | - | Y |RSSM_Client_Count   |
     RSSM_net_avg_wait_time | D || - | - | t || - | - | Y |RSSM_Avg_Net_Wait_T-|
                            |   ||   |   |   ||   |   |   |ime                 |
         RSSM_net_wait_time | D || - | - | t || - | - | Y |RSSM_Total_Net_Wait-|
                            |   ||   |   |   ||   |   |   |_Time               |
             RSSM_net_waits | D || - | - | t || - | - | Y |RSSM_Net_Wait_Count |
              RSSM_no_times | G || - | - | t || - | - | Y |RSSM_Off_Count      |
                 RSSM_no_tx | D || - | - | t || - | - | Y |RSSM_Ack_Miss_Count |
                RSSM_status | D || - | - | t || - | - | Y |                    |
     RSSM_timefunc_failures | D || - | - | t || - | - | Y |RSSM_Time_Function_-|
                            |   ||   |   |   ||   |   |   |Failure_Count       |
      RSSM_tx_avg_wait_time | D || - | - | t || - | - | Y |RSSM_Avg_Transactio-|
                            |   ||   |   |   ||   |   |   |n_Wait_Time         |
          RSSM_tx_wait_time | D || - | - | t || - | - | Y |RSSM_Total_Transact-|
                            |   ||   |   |   ||   |   |   |ion_Wait_Time       |
              RSSM_tx_waits | D || - | - | t || - | - | Y |RSSM_Transaction_Wa-|
                            |   ||   |   |   ||   |   |   |it_Count            |
    RSSM_wait_pos_backtraver| D || - | - | t || - | - | Y |RSSM_Back_Traversal-|
                            |   ||   |   |   ||   |   |   |_Count              |
         RSSM_wait_sessions | G || - | - | t || - | - | Y |RSSM_Wait_Session_C-|
                            |   ||   |   |   ||   |   |   |ount                |
                RSSM_yes_tx | D || - | - | t || - | - | Y |RSSM_Ack_Count      |
                RSSS_status | I || - | - | t || - | - | Y |                    |
     Slave_heartbeat_period = CHANGE MASTER TO MASTER_HEARTBEAT_PERIOD
     Slave_open_temp_tables | S || - | - | t || - | - | Y |Open_Tables         |
  Slave_received_heartbeats | I || - | - | t || - | - | Y |Received_Heartbeats |
 Slave_retried_transactions | S || - | - | t || - | - | Y |Retried_Transactions|
              Slave_running | G || - | - | t || - | - | - |                    |
Unexposed fields -----------+---++---+---+---++---+---+---+--------------------+
relay log where IOthd writes| I || - | - | - || Y |!I | Y |File_Slave          |
position where IOthd writes | I || - | - | - || Y |!I | Y |Position_Slave      |
dump thd's heartbeat period | D || - | - | - || - | - | Y |Heartbeat_Period    |
 timestamp of last_io_error | I || - | - | - || Y | Y | Y |Last_Error_Time     |
timestamp of last_sql_error | S || - | - | - || Y | Y | Y |Last_Error_Time     |
================================================================================

Footnotes:

(1) Slave_IO_Running and Slave_SQL_Running determine the current state
    of the SQL and IO thread.  We could make these persistent, so that
    after server restart, the same threads are started again as were
    running when the server was shut down. The --skip-slave-start
    would then suppress starting any slave. We then need to make the
    following fields persistent: sql_slave_skip_counter, the UNTIL fields,
    Last_*_Error, etc.

(2) In the most generic definition, Seconds_Behind_Master measures how
    long a particular SQL thread is behind a particular master, so the
    scope depends on *both* an IO thread and an SQL thread.  To avoid
    adding a new scope for only this field, we can define
    Seconds_Behind_Master to measure the maximal time, over all SQL
    threads, we are behind a particular master.  This is in any case a
    meaningful measurement because it shows the oldest un-applied
    event from each master.  So we define the scope to be IO thread.
The following table schemas, CHANGE commands, and system variables were
generated using the attached script get_schemas_version_2.

For now, all fields are ordered alphabetically. It may be possible to order
fields in a more logical way (similar fields in adjacent columns). If there is a
sufficient demand to order fields logically, we can do that. However, note when
new fields are added in the future, they have to be added to the end. So a
consistent ordering cannot be maintained.

  Columns in mysql.io_thread:
    Compressed_Protocol
    Connection_Retry_Count
    Do_Same_Server_Id
    File_Master
    File_Slave
    Heartbeat_Period
    Host
    Ignore_Server_Ids
    Last_Errno
    Last_Error
    Last_Error_Time
    Master_UUID
    Net_Timeout
    Network_Interface
    Password
    Port
    Position_Master
    Position_Slave
    Report_Authentication_Info
    Report_Host
    Report_Password
    Report_Port
    Report_User
    SSL_Allowed
    SSL_CA_File
    SSL_CA_Path
    SSL_Certificate
    SSL_Cipher
    SSL_Key
    SSL_Verify_Server_Certificate
    Thread_Running
    User

  Columns in mysql.sql_thread:
    Delay
    Do_DB
    Do_Table
    Execution_Mode
    File_Master
    File_Slave
    Ignore_DB
    Ignore_Table
    Init_Statement
    Last_Errno
    Last_Error
    Last_Error_Time
    Load_Tmpdir
    Log_Slow_Statements
    Log_Updates
    Position_Master
    Position_Slave
    Rewrite_DB
    Skip_Counter
    Skip_Errors
    Thread_Running
    Transaction_Retries
    Type_Conversions
    Until_File_Master
    Until_File_Slave
    Until_Position_Master
    Until_Position_Slave
    Wildcard_Do_Table
    Wildcard_Ignore_Table

  Columns in mysql.relay_log:
    Automatic_Purge
    File_Basename
    Index_File
    Max_Disk_Usage
    Max_File_Size
    Sync_Frequency

  Columns in mysql.dump_thread:
    <none>

  Columns in mysql.binlog:
    Default_Cache_Size
    Do_DB
    Enabled
    File_Basename
    Ignore_DB
    Index_File
    Max_Cache_Size
    Max_File_Size
    Max_Row_Event_Size
    Policy
    Write_Non_Transactional_Updates_Directly

  Columns in PERFORMANCE_SCHEMA.IO_THREAD:
    Compressed_Protocol
    Connection_Retry_Count
    Disconnect_Event_Count
    Do_Same_Server_Id
    File_Master
    File_Slave
    Heartbeat_Period
    Host
    Ignore_Server_Ids
    Last_Errno
    Last_Error
    Last_Error_Time
    Master_Server_Id
    Master_UUID
    Net_Timeout
    Network_Interface
    Password
    Port
    Position_Master
    Position_Slave
    Report_Authentication_Info
    Report_Host
    Report_Password
    Report_Port
    Report_User
    Run_State
    SSL_Allowed
    SSL_CA_File
    SSL_CA_Path
    SSL_Certificate
    SSL_Cipher
    SSL_Key
    SSL_Verify_Server_Certificate
    Seconds_Behind_Master
    Thread_Running
    User

  Columns in PERFORMANCE_SCHEMA.SQL_THREAD:
    Abort_Event_Count
    Delay
    Do_DB
    Do_Table
    Execution_Mode
    File_Master
    File_Slave
    Ignore_DB
    Ignore_Table
    Init_Statement
    Last_Errno
    Last_Error
    Last_Error_Time
    Load_Tmpdir
    Log_Slow_Statements
    Log_Updates
    Position_Master
    Position_Slave
    Remaining_Delay
    Rewrite_DB
    Run_State
    Skip_Counter
    Skip_Errors
    Thread_Running
    Transaction_Retries
    Type_Conversions
    Until_File_Master
    Until_File_Slave
    Until_Position_Master
    Until_Position_Slave
    Wildcard_Do_Table
    Wildcard_Ignore_Table

  Columns in PERFORMANCE_SCHEMA.RELAY_LOG:
    Automatic_Purge
    Disk_Usage
    File_Basename
    Index_File
    Max_Disk_Usage
    Max_File_Size
    Recovery
    Sync_Frequency

  Columns in PERFORMANCE_SCHEMA.DUMP_THREAD:
    File
    Heartbeat_Period
    Host
    Max_Events
    Port
    Position
    Server_Id
    Sporadic_Failures
    UUID

  Columns in PERFORMANCE_SCHEMA.BINLOG:
    Default_Cache_Size
    Do_DB
    Enabled
    File_Basename
    Ignore_DB
    Index_File
    Max_Cache_Size
    Max_File_Size
    Max_Row_Event_Size
    Policy
    Write_Non_Transactional_Updates_Directly

  Commands on the form CHANGE IO_THREAD <id> TO ... = <value>:
    COMPRESSED_PROTOCOL
    CONNECTION_RETRY_COUNT
    DISCONNECT_EVENT_COUNT
    DO_SAME_SERVER_ID
    FILE_MASTER
    FILE_SLAVE
    HEARTBEAT_PERIOD
    HOST
    IGNORE_SERVER_IDS
    LAST_ERRNO
    LAST_ERROR
    LAST_ERROR_TIME
    NETWORK_INTERFACE
    NET_TIMEOUT
    PASSWORD
    PORT
    POSITION_MASTER
    POSITION_SLAVE
    REPORT_AUTHENTICATION_INFO
    REPORT_HOST
    REPORT_PASSWORD
    REPORT_PORT
    REPORT_USER
    SSL_ALLOWED
    SSL_CA_FILE
    SSL_CA_PATH
    SSL_CERTIFICATE
    SSL_CIPHER
    SSL_KEY
    SSL_VERIFY_SERVER_CERTIFICATE
    USER

  Commands on the form CHANGE SQL_THREAD <id> TO ... = <value>:
    ABORT_EVENT_COUNT
    DELAY
    DO_DB
    DO_TABLE
    EXECUTION_MODE
    FILE_MASTER
    FILE_SLAVE
    IGNORE_DB
    IGNORE_TABLE
    INIT_STATEMENT
    LAST_ERRNO
    LAST_ERROR
    LAST_ERROR_TIME
    LOAD_TMPDIR
    LOG_SLOW_STATEMENTS
    LOG_UPDATES
    POSITION_MASTER
    POSITION_SLAVE
    REWRITE_DB
    SKIP_COUNTER
    SKIP_ERRORS
    TRANSACTION_RETRIES
    TYPE_CONVERSIONS
    UNTIL_FILE_MASTER
    UNTIL_FILE_SLAVE
    UNTIL_POSITION_MASTER
    UNTIL_POSITION_SLAVE
    WILDCARD_DO_TABLE
    WILDCARD_IGNORE_TABLE

  Commands on the form CHANGE RELAY_LOG <id> TO ... = <value>:
    AUTOMATIC_PURGE
    FILE_BASENAME
    INDEX_FILE
    MAX_DISK_USAGE
    MAX_FILE_SIZE
    RECOVERY
    SYNC_FREQUENCY

  Commands on the form CHANGE DUMP_THREAD <id> TO ... = <value>:
    MAX_EVENTS
    SPORADIC_FAILURES

  Commands on the form CHANGE BINLOG <id> TO ... = <value>:
    DEFAULT_CACHE_SIZE
    DO_DB
    ENABLED
    FILE_BASENAME
    IGNORE_DB
    INDEX_FILE
    MAX_CACHE_SIZE
    MAX_FILE_SIZE
    MAX_ROW_EVENT_SIZE
    POLICY
    WRITE_NON_TRANSACTIONAL_UPDATES_DIRECTLY

  Session io_thread variables:
    <none>

  Session sql_thread variables:
    <none>

  Session relay_log variables:
    <none>

  Session dump_thread variables:
    <none>

  Session binlog variables:
    default_binlog_do_db
    default_binlog_enabled
    default_binlog_ignore_db
    default_binlog_max_row_event_size
    default_binlog_policy
    default_binlog_write_non_transactional_updates_directly

  Session sql_thread variables:
    <none>

  Global io_thread variables:
    default_io_thread_compressed_protocol
    default_io_thread_connection_retry_count
    default_io_thread_disconnect_event_count
    default_io_thread_do_same_server_id
    default_io_thread_heartbeat_period
    default_io_thread_ignore_server_ids
    default_io_thread_net_timeout
    default_io_thread_report_authentication_info
    default_io_thread_report_host
    default_io_thread_report_password
    default_io_thread_report_port
    default_io_thread_report_user
    default_io_thread_ssl_allowed
    default_io_thread_ssl_ca_file
    default_io_thread_ssl_ca_path
    default_io_thread_ssl_certificate
    default_io_thread_ssl_cipher
    default_io_thread_ssl_key
    default_io_thread_ssl_verify_server_certificate
    default_io_thread_sync_master_info

  Global sql_thread variables:
    default_sql_thread_abort_event_count
    default_sql_thread_delay
    default_sql_thread_do_db
    default_sql_thread_do_table
    default_sql_thread_execution_mode
    default_sql_thread_ignore_db
    default_sql_thread_ignore_table
    default_sql_thread_init_statement
    default_sql_thread_load_tmpdir
    default_sql_thread_log_slow_statements
    default_sql_thread_log_updates
    default_sql_thread_rewrite_db
    default_sql_thread_skip_errors
    default_sql_thread_sync_relay_log_info
    default_sql_thread_transaction_retries
    default_sql_thread_type_conversions
    default_sql_thread_wildcard_do_table
    default_sql_thread_wildcard_ignore_table

  Global relay_log variables:
    default_relay_log_automatic_purge
    default_relay_log_max_disk_usage
    default_relay_log_max_file_size
    default_relay_log_recovery
    default_relay_log_sync_frequency

  Global dump_thread variables:
    default_dump_thread_max_events
    default_dump_thread_sporadic_failures

  Global binlog variables:
    default_binlog_default_cache_size
    default_binlog_do_db
    default_binlog_enabled
    default_binlog_ignore_db
    default_binlog_max_cache_size
    default_binlog_max_file_size
    default_binlog_max_row_event_size
    default_binlog_policy
    default_binlog_write_non_transactional_updates_directly

  Global variables:
    auto_increment_increment
    auto_increment_offset
    binlog_trust_function_creators
    read_only
    server_id
    skip_slave_start