MDEV-38202: make init_rpl_role visible at runtime by Mahmoud-kh1 · Pull Request #4904 · MariaDB/server

Mahmoud-kh1 · 2026-04-04T15:59:10Z

This PR adds a new feature to see the server’s initial replication role at runtime.

I added a new read-only status variable init_rpl_role that captures the value of rpl_status right after startup and keeps it unchanged.

Reason
Previously, init_rpl_role could be set in the cnf file but was not visible in runtime which will be helpful for investigating issues as it will allow us to see with which value mariadb was started.

Tests :
Added basic tests to verify that init_rpl_role is correctly set at startup and displayed properly.

gkodinov

Thank you for your contribution! This is a preliminary review.

Please, in addition to the notes below:

add a commit message to your commit explaining what it is that you do
update the Jira with a complete description of what the new variable is (data type, validity period, purpose), when and how it can be set, etc. : helps documenting it.
Make sure that there are no failing buildbot hosts.

gkodinov · 2026-04-06T07:50:49Z

       NOT_IN_BINLOG, ON_CHECK(check_init_string));

+#ifdef HAVE_REPLICATION 
+static Sys_var_enum Sys_init_rpl_role(  


Feel free to leave that to the final reviewer. But: is there any specific reason this should be a system variable?
It's read only at runtime and not settable via the command line/config file at startup. So, in essence, you can only read it. So why not make this a status variable?

I just make it system variable to support this syntax
SELECT @@global.init_rpl_role;
SELECT @@init_rpl_role;

again, why? what's better about this syntax compared to SHOW GLOBAL STATUS LIKE 'init_rpl_role' ?

I thought it will be just a nice bonus :) , I will turn it to status variable as you suggested.

I stumbled upon the System & Status Variables Guide.

In general, I believe this should be a system variable, as it’s associated with a mode configuration rather than a status report.

In theory, it is possible to make --init-rpl-role mutable during runtime for recovering complex Semi-Sync networks/situations.
But in practice, --init-rpl-role doesn’t scale. (see also MDEV-34878)

FWIW, I've requested that this is a status variable for the following reasons:

I've assumed that a value will never be assigned directly to it.

Status variables are more light-weight than system variables: less locking needed etc.

I personally find a non-settable system variable to be an abomination and a gotcha: why would you put something non-settable in a settable variables namespace?

This said, it's your review and your codebase. So feel free to ignore the above or not.

I've assumed that a value will never be assigned directly to it.

Status variables are more light-weight than system variables: less locking needed etc.

I personally find a non-settable system variable to be an abomination and a gotcha: why would you put something non-settable in a settable variables namespace?

There are existing global read-only variables.
But yes, the system variables system should solve these missed optimizations.

Hi @ParadoxV5 I return it back to be a system variable .

gkodinov

Thank you for making it a status variable!

Some cleanups below. And then it's ready.

ParadoxV5 · 2026-04-07T21:36:23Z

       NOT_IN_BINLOG, ON_CHECK(check_init_string));

+#ifdef HAVE_REPLICATION 
+static Sys_var_enum Sys_init_rpl_role(  


I stumbled upon the System & Status Variables Guide.

In general, I believe this should be a system variable, as it’s associated with a mode configuration rather than a status report.

In theory, it is possible to make --init-rpl-role mutable during runtime for recovering complex Semi-Sync networks/situations.
But in practice, --init-rpl-role doesn’t scale. (see also MDEV-34878)

gkodinov

LGTM. Thank you for your work. Please stay tuned for the final review.

ParadoxV5

Thanks and well done on the first-time contribution, @Mahmoud-kh1!

ParadoxV5

Are you still cleaning up?

The expected results of sys_vars.sysvars_server_notembedded and main.mysqld--help tests need updates to match the new refined description.
You can have path/to/mtr --record suite_name.test_name rewrite the results if you don’t like manual copy-pastes.

While there, some small details that I missed last time:

Your added lines have numerous (unnecessary) trailing spaces. Please clean them up.
Re. the commit message
- It still says “status variable” 😄.
- The last paragraph of your commit message (added later?) exceeds the guidelines.
  I suggest breaking the line up:
```
Example usage:
* SHOW GLOBAL VARIABLES LIKE 'init_rpl_role'
* SELECT @@GLOBAL.init_rpl_role;
```
- Would you like to include the reviewers?
```
Reviewed-by: ParadoxV5 <paradox.ver5@gmail.com>
Reviewed-by: Georgi (Joro) Kodinov <joro@mariadb.org>
```
- Nit: doubled space in … investigation issues because

Problem: The --init-rpl-role option can be set in the .cnf file or command line to configure the server replication role at startup (MASTER or SLAVE), but there was no way to check this value at runtime. This made it hard to investigate issues because we could not know which role the server was started with. Solution: I added a new read-only system variable init_rpl_role that is set after startup and kept unchanged. Example usage: * SHOW GLOBAL VARIABLES LIKE 'init_rpl_role' * SELECT @@GLOBAL.init_rpl_role Reviewed-by: ParadoxV5 <paradox.ver5@gmail.com> Reviewed-by: Georgi (Joro) Kodinov <joro@mariadb.org>

ParadoxV5 · 2026-04-17T00:33:13Z

LGTM except a few remaining trailing spaces

ParadoxV5 · 2026-04-17T00:39:43Z

Oh, almost forgot:
Before merging new features, they also need to be approved by QA and typically pre-released in a preview build for at least one release cycle.
QA will let us know when this is good to go.

P.S.
Meanwhile, if you’d like something to do, try preparing an edit for https://github.com/mariadb-corporation/mariadb-docs!

Mahmoud-kh1 force-pushed the init_rpl_role branch 6 times, most recently from f6f6a30 to 029860e Compare April 4, 2026 17:30

gkodinov added the External Contribution All PRs from entities outside of MariaDB Foundation, Corporation, Codership agreements. label Apr 6, 2026

gkodinov requested changes Apr 6, 2026

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Mahmoud-kh1 force-pushed the init_rpl_role branch 3 times, most recently from 1979739 to 8795f3b Compare April 7, 2026 12:17

Mahmoud-kh1 changed the title ~~MDEV-38202: add init_rpl_role in SHOW VARIABLES~~ MDEV-38202: make init_rpl_role visible at runtime Apr 7, 2026

Mahmoud-kh1 requested a review from gkodinov April 7, 2026 12:51

gkodinov requested changes Apr 7, 2026

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Comment thread mysql-test/suite/sys_vars/t/init_rpl_role_variable_basic.test Outdated

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Mahmoud-kh1 force-pushed the init_rpl_role branch from 8795f3b to 648ee9c Compare April 7, 2026 13:24

Mahmoud-kh1 requested a review from gkodinov April 7, 2026 13:25

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gkodinov approved these changes Apr 8, 2026

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Mahmoud-kh1 force-pushed the init_rpl_role branch from 648ee9c to c732a37 Compare April 10, 2026 11:13

Mahmoud-kh1 requested a review from ParadoxV5 April 10, 2026 12:07

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Mahmoud-kh1 force-pushed the init_rpl_role branch 2 times, most recently from 98393ff to d9aa486 Compare April 11, 2026 20:59

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Mahmoud-kh1 force-pushed the init_rpl_role branch 3 times, most recently from 37a4765 to e74a17c Compare April 11, 2026 22:09

Mahmoud-kh1 requested a review from ParadoxV5 April 11, 2026 22:13

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Mahmoud-kh1 force-pushed the init_rpl_role branch 5 times, most recently from 839be78 to 8f83b3b Compare April 13, 2026 01:17

Mahmoud-kh1 requested a review from ParadoxV5 April 13, 2026 01:48

Mahmoud-kh1 force-pushed the init_rpl_role branch from 8f83b3b to ad3c424 Compare April 14, 2026 17:11

ParadoxV5 approved these changes Apr 17, 2026

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LGTM except a few remaining trailing spaces

ParadoxV5 unassigned gkodinov Apr 17, 2026

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