Clarify in docs that limited length keys apply to indexes only, enforce in code

Rebased and adjusted

Wonder if the title/issue summary could be updated. Since it's applying to more then documents. Also see it was tagged for a CR if that could happen too please.

Trying to make issue title and summary clearer.

Agreed this is not a Documentation only issue, removed tag - docs need update because these changes are applied.

Working on CR and patch update.

Added a draft CR, https://www.drupal.org/node/3375071 →

Thanks @mondrake! Much clearer.

Wasn't entirely sure how to test so I did something similar to testInvalidPrimaryKeyColumnsOnCreateTable and your CR and created a table with a a primary key of 10. And got the exception as expected.

The CR was clear of the change and included great examples.

Think this is ready for committers to take a look.

Mostly looks good but a handful of comments on the MR.

Replied inline and adjusted the deprecation messages.

lets find out!

I'm pretty sure it won't, so we should either duplicate the documentation, or add @see in the relevant places, and/or file an api.drupal.org issue to support it.

Filed ✨ Support PHPStan's annotations for local type aliases and array shapes Active in the API module issue queue - if in the future we want to use PHPStan to higher levels we can't be stopped by that, so better request a change there now.

Tests for index limits for pgsql/sqlite requested in #3389202-10: migrate\Plugin\migrate\id_map\Sql assumes a PDO db driver →

@fjgarlin I commented inline - can you please elaborate the suggestion?