[spark] Add rollback ddl syntax

[askwang]

Purpose

Add rollback to snapshot/tag/timestamp ddl syntax.

alter table t rollback to snapshot `2`;
alter table t rollback to tag `test-tag`;
alter table t rollback to timestamp `1730876906134`;

Tests

API and Format

Documentation

[LinMingQiang]

Why do we need a new alter ddl syntax. Is it the same as the call procedure ?

[wwj6591812]

Can not delete tag?

[askwang]

my mistake, updated, ths

[askwang]

Why do we need a new alter ddl syntax. Is it the same as the call procedure ?

SQL syntax support will be provided later, it is the same as procedure call.

[LinMingQiang]

Why do we use alter table instead of call if they are the same? And alter table should be used to modify the table metadata information, like alter table add col.

[askwang]

Why do we use alter table instead of call if they are the same? And alter table should be used to modify the table metadata information, like alter table add col.

I think tag/snapshot are also part of the table meta info, maybe we can use alter table to modify it.

[JingsongLi]

timeTravelKind?

[askwang]

changed.

[JingsongLi]

Why do we use alter table instead of call if they are the same? And alter table should be used to modify the table metadata information, like alter table add col.

I agree with your idea. I have checked and currently no other lake formats have implemented custom syntax here. We can consider temporarily stopping and using CALL is not a bad idea.

@askwang What do you think?

[Zouxxyy]

In my mind, rollback should actually generate a new snapshot containing the changes, from this perspective, alter table should not be used. (although the current implementation directly deletes the existing snapshots).

Besides in spark doc description: ALTER TABLE statement changes the schema or properties of a table.

[askwang]

Why do we use alter table instead of call if they are the same? And alter table should be used to modify the table metadata information, like alter table add col.

I agree with your idea. I have checked and currently no other lake formats have implemented custom syntax here. We can consider temporarily stopping and using CALL is not a bad idea.

@askwang What do you think?

ok