[GitHub] [flink] bowenli86 opened a new pull request #8458: [FLINK-12452][table][hive] alterTable() should ensure existing base table and the new one are of the same type

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bowenli86 opened a new pull request #8458: [FLINK-12452][table][hive] alterTable() should ensure existing base table and the new one are of the same type
URL: https://github.com/apache/flink/pull/8458
 
 
   ## What is the purpose of the change
   
   Currently all catalogs doesn't check if existing base table and the new one are of the same type in alterTable(), e.g. existing table is a view but user tries to replace it with a table. This PR adds such checks to all catalogs
   
   ## Brief change log
   
   - added check in in-memory catalog to make sure existing and new table are of the same classes since in-memory catalog theoretically can store any table and view implementations 
   - added checks in `HiveCatalogBase` to make sure 1) existing and new table are of the same type 2) not alter existing Hive tables in types that Flink cannot create for now, including EXTERNAL_TABLE, INDEX_TABLE and MATERIALZED_VIEW. Flink of course cannot alter existing ones if it cannot create them.
   
   Note that though Flink cannot create them, it's able to read most parts of their metadata, like schema and properties, thru existing mechanism, but not their unique metadata. 
   
   Also note that add capability of creating EXTERNAL_TABLE should be fairly easy to do, e.g. with a table property "table_type=external", we just haven't done it yet.  INDEX_TABLE and MATERIALZED_VIEW need more research.
   
   ## Verifying this change
   
   Added new unit tests in `GenericInMemoryCatalogTest` and `CatalogTestBase`.
   
   ## Does this pull request potentially affect one of the following parts:
   
     - Dependencies (does it add or upgrade a dependency): (no)
     - The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (no)
     - The serializers: (no)
     - The runtime per-record code paths (performance sensitive): (no)
     - Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
     - The S3 file system connector: (no)
   
   ## Documentation
   
     - Does this pull request introduce a new feature? (no)
     - If yes, how is the feature documented? (not applicable)
   

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