Rework MDL enum constants values

[pranavktiwari]

fixes MDEV-39184

Problem:

MDL tests results ordering is not deterministic.

Fix

Added --sorted_result to the MDL tests to ensure deterministic ordering of metadata_lock_info output. Since MDL lock iteration order depends on hash_value() and underlying Split-Ordered List behavior, it may vary with
internal changes such as enum value shifts.

[CLAassistant]

All committers have signed the CLA.

[midenok]

Hi @pranavktiwari,

Thank you for the patch! Now I see that change for MDL_BIT has negative effect on performance which is unwanted. I'd better tell in the description that it is investigation task and should be evaluated for push. Nonetheless, if we rework enum_mdl_type into bitmask values we would not need MDL_BIT() at all. What other problems occur if we try that?

It seems that I cannot recognize the changes for the second part of the ticket (about enum_mdl_namespace). Is it feasible to do these changes? Can you try to do it on the minimal set of code, without plugins and minor storage engines?

[Copilot]

Pull request overview

This PR reworks MDL enum constant values so that 0 represents an uninitialized MDL state (instead of mapping to real lock types), and updates related mappings/output so metadata lock reporting continues to work.

Changes:

• Shifted enum_mdl_type / backup-stage lock constants so MDL_NOT_INITIALIZED becomes 0.
• Introduced MDL_key::NOT_INITIALIZED=0 namespace and updated handlers/mappings accordingly.
• Updated incompatibility matrices, metadata-lock name tables, and adjusted mysql-test expected results.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
sql/sp.h	Adds handling for MDL_key::NOT_INITIALIZED in namespace→handler switch.
sql/mdl.h	Updates MDL type and namespace enums and shifts backup lock constants.
sql/mdl.cc	Adds NOT_INITIALIZED PSI stage entry, pads name tables, and pads incompatibility arrays.
plugin/metadata_lock_info/metadata_lock_info.cc	Adds “Not initialised” entry to namespace name table.
mysql-test/main/mdl_sync.result	Updates expected output ordering for MDL metadata_lock_info.
mysql-test/main/mdl.result	Updates expected output ordering for MDL metadata_lock_info.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

MDL_key::enum_mdl_namespace now has NOT_INITIALIZED (index 0) and a corresponding PSI stage entry was added. However, wsrep_get_mdl_namespace_name() (later in this file) does not handle MDL_key::NOT_INITIALIZED, so wsrep debug output will report the namespace as "UNKNOWN" for this new value. Add an explicit case for NOT_INITIALIZED to keep diagnostics accurate (and to avoid -Wswitch-enum warnings if enabled).

[midenok]

This comment should be removed too.