Description:

Fixes #19648

Moves all MySQL specific code from core/Db, core/DbHelper and all classes under core/Db/ to the database adapter classes core/Adapter/Pdo/Mysql, core/Adapter/Mysqli and a new shared class core/Adapter/MysqlAdapterCommon for methods common for both.

Updates for tracker Db classes core/Tracker/Db, core/Tracker/Db/Pdo/Mysql and core/Tracker/Db/Mysqli are also included.

The overall objective of these changes is to be able to add a new core/Db/Adapter/Pdo/[some new db], core/Db/Schema/[some new db] and core/Tracker/Db/Pdo/[some new db] where 'some new db' supports prima facie MySQL style queries but has a different underlying architecture with differences in schema, indices, key type, engine type, error codes and session variables.

The previous branch suffered from the dreaded submodules 'not our ref' error so this a replacement branch/PR

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed