[POC] Prototyping - MySQL User Defined Types

[marcalff]

Proof Of Concepts - MySQL User Defined Types

Contributes to #674

Caution

Proof of concepts code, do not merge, do not use in production.

This code is dirty and to throw away.
The point of this PR is to do prototyping, to identify what needs to be changed in the server, to start a technical discussion.

Quick start

Build

Compile with -DWITH_EXPERIMENTAL_UDT=ON -DWITH_DEBUG=ON in CMake.

Run

mtr --suite=udt

Current progress

Declare a UDT and provide an implementation:

CREATE TYPE test.complex_number AS BINARY(16);

INSTALL COMPONENT "file://component_udt_example";

Declare a UDT variable, perform operations provided by the component:

delimiter $$

CREATE PROCEDURE test.complex()
BEGIN
  DECLARE a test.complex_number;
  DECLARE b test.complex_number;
  DECLARE c test.complex_number;
  SET a = complex_number_from_string("1+2i");
  SET b = complex_number_from_string("3+4i");
  SET c = complex_number_add(a, b);
  # SELECT complex_number_to_string(c);
END$$

delimiter ;

Invoke the UDT implementation at runtime:

call test.complex();

Cleanup:

UNINSTALL COMPONENT "file://component_udt_example";

DROP PROCEDURE test.complex;

Component implementation

Check files under components/udt_example.

---

Copyright (c) 2026, Oracle and/or its affiliates.

What does this change do?

Why is it needed?

How was it tested?

• Added/updated MTR tests under mysql-test/
• scripts/ci/mtr.sh passes locally
• Ran the relevant full suite (name it): ______

Contributor checklist

• I have signed the OCA with the email on these commits
• Code is formatted (scripts/ci/format.sh)
• Commits are focused with descriptive messages

AI assistance

• I did not use AI assistance for this contribution
• I used AI assistance for this contribution

If AI assistance was used, describe the tool(s) and extent of use:

Areas touched

[marcalff]

Closing and re creating, should be in a git branch

Closed in favor of #707