fix select star, col1 orderby col1 bug.

[yangxuanjia]

shard env.
fix select star, col1 orderby col1 bug.
The problem is col1 parse index is 1. But before this column, there have a star(*), this will be some column.
so finally orderby from multi shards, use order index 1 will be make a bug.
This is a company inner fix, base on Vitess 6.0.

So I not really sure, Vitess9.0 whether is fix this bug or doesn't support this typical sql.

select t.*, t.customer_id from customer t where email = 'aaa11' order by customer_id desc limit 0, 3;

[systay]

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.

[systay]

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

[yangxuanjia]

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

[frouioui]

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.

[systay]

Thank you @yangxuanjia for this contribution.

Long term, I think we should rewrite queries so that when the query gets to the planner, star expressions have been expanded, but until then, this is solving a real problem. Much appreciated.