HIVE-29177: Implement default Catalog selection

[zhangbutao]

What changes were proposed in this pull request?

TODO: Add more test and cover more api.

Why are the changes needed?

Does this PR introduce any user-facing change?

How was this patch tested?

[sonarqubecloud]

Quality Gate passed

Issues
96 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Neer393]

@zhangbutao I think we need a default database created whenever a user creates new catalog so that ideally when a user switches catalog, we point to the default database within it
What do you think ?

[zhangbutao]

@zhangbutao I think we need a default database created whenever a user creates new catalog so that ideally when a user switches catalog, we point to the default database within it What do you think ?

@Neer393 Currently(without this PR), when a new catalog is created, a default database will also be created.

With this PR, when a user switches catalogs using SET CATALOG catName, it should not point to the default database by default. The user should explicitly specify a database through USE dbName or USE catName.dbName xxx to maintain maximum compatibility with previous usage patterns.
Please check catalog_database.q https://github.com/apache/hive/pull/6088/files#diff-0a99f71cb21eb68f9efe36ff59f2005f696ef9ea6b660aef5cc184152018f79b