Feature Request: SQL syntax for schema tracking

[aparajon]

Feature Description

Add SQL syntax that can detect the status of schema tracking and/or trigger it to catch up.

One possible way that this can look like:

>  show schema_tracking;
+--------------+
| Status       |
+--------------+
| IN_PROGRESS  |
+--------------+

> await schema_tracking;
+--------------+
| Status       |
+--------------+
| COMPLETE     |
+--------------+

Use Case(s)

A client app might want to run these commands against the vtgate before issuing further app specific SQL commands. Specifically, this would be useful for tests that run against vttestserver, as there can be a case where all .sql migrations appear to be applied but schema tracking has not yet caught up and the error VT09015: schema tracking required gets emitted.

The context / motivation for this feature request originates from this Slack thread. It seems like schema tracking is actually enabled based on schema_change_signal and queryserver-config-schema-change-signal having a default value of true in vtcombo. And FYI, it seems like I only hit this error in versions of Vitess >= 18, as I haven't yet hit this issue after downgrading tests to run against v17. I'm also open to exploring other ideas or suggestions on how to wait for schema tracking to complete.

[harshit-gangal]

It interests me that the issue does not exist on v17 and only happens for v18+.
Can you share the Vschema and the query on which you see the error?

[aparajon]

Shared privately