Hi @yangxuanjia!

Thank you so much for sharing this fix with us.
We need two things to make progress on this PR. First, we need all commits to have a signoff signature to be acceptable.

1. You will need to amend your commits with git commit --amend --signoff so they can be legally accepted. Let me know if this is an issue and I can guide you through it.

2. We need tests to be added, showing what you are trying to accomplish. I think adding something to the postprocess.txt could work.

Oh, and I see that you will also need to do a make sizegen to update the CachedSize methods

Hi @systay,
I done the work, please review it at your earliest convenience.

Hello 👋 Looked at the changes earlier with @systay, it looks like a great fix. However, we are still trying to understand if the use of starColFixedIndex can be avoided by using only orderBy.

I personally think we should add an error message in planRouteOrdering where we break (go/vt/vtgate/planbuilder/ordering.go:308). For instance, if the query below was allowed one day, it would break and starColFixedIndex would be incorrect.

select *, t.id from user t, user_extra where t.email = 'aaa11' order by t.id desc limit 0, 3;

Today's code returns the error "unsupported: '*' expression in cross-shard query", a similar message can be added in planRouteOrdering.