ApplySchema vttablet RPC: allow special characters in table and column names

[rohit-nayak-ps]

Description

VReplication MoveTables workflows which contain a table name or a column which has special characters (like ö or ü) are currently failing. While tracking down the issue it turned out that the target table/column names are being generated with incorrect character mappings.

Root Cause

VReplication uses the tabletmanagers ApplySchema RPC to copy over the schemas from the source to the target.

It turns out that ApplySchema executes the actual ddl using the mysql CLI in the mysqlctl package!! It is not clear why we are following this approach instead of directly creating it in the tablet like how OnlineDDL does it, for example: this code was added way back ~2016. It is possible this is legacy and can be refactored out.

This PR sets the default character set in the extra config that is passed on to the CLI ( --default-character-set=utf8mb4) command line argument. An existing e2e test has been updated to use special characters in both table and column names. It was failing before this change and passes with the change.

Related Issue(s)

• Fixes: MoveTables workflow fails when table names or column names have special characters #13069

Checklist

• "Backport to:" labels have been added if this change should be back-ported
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on the CI
• Documentation was added or is not required

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• If this is a change that users need to know about, please apply the release notes (needs details) label so that merging is blocked unless the summary release notes document is included.
• If a test is added or modified, there should be a documentation on top of the test to explain what the expected behavior is what the test does.

If a new flag is being introduced:

• Is it really necessary to add this flag?
• Flag names should be clear and intuitive (as far as possible)
• Help text should be descriptive.
• Flag names should use dashes (-) as word separators rather than underscores (_).

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow should be required, the maintainer team should be notified.

Bug fixes

• There should be at least one unit or end-to-end test.
• The Pull Request description should include a link to an issue that describes the bug.

Non-trivial changes

• There should be some code comments as to why things are implemented the way they are.

New/Existing features

• Should be documented, either by modifying the existing documentation or creating new documentation.
• New features should have a link to a feature request issue or an RFC that documents the use cases, corner cases and test cases.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• vtctl command output order should be stable and awk-able.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from VTop, if used there.

[vitess-bot]

I was unable to backport this Pull Request to the following branches: release-16.0.