More properly guard against concurrent schemaless table creations and alterations

[MichaelScofield]

What type of enhancement is this?

Refactor

What does the enhancement do?

Now the schemaless table creations and alterations are run concurrently (introduced by #1687 ). This could cause some issues when running concurrently. For example, unique table ids are wasted, or unnecessary calls to Metasrv. We should properly guard against it in Frontend.

Implementation challenges

No response

[MichaelScofield]

Although the schemaless table creations and alterations are reverted back to serialized execution now, we can still benifit from adding a lock to control the concurrency, avoiding doing some unnecessary work.

[sunray-ley]

I want to have a try.

[MichaelScofield]

thx @sunray-ley , assigned

[killme2008]

@MichaelScofield Looks like we don't have this problem currently after we used procedures for all DDL statements. Could you check it?

[MichaelScofield]

@killme2008 This problem is gone not because we are using procedure but the schemaless table creations are changed back to serial mode.