bowenli86 commented on a change in 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#discussion_r284882741
##########
File path:
flink-connectors/flink-connector-hive/src/main/java/org/apache/flink/table/catalog/hive/HiveCatalogBase.java
##########
@@ -318,13 +320,44 @@ public void alterTable(ObjectPath tablePath,
CatalogBaseTable newCatalogTable, b
throw new
TableNotExistException(catalogName, tablePath);
}
} else {
- // TODO: [FLINK-12452] alterTable() in all
catalogs should ensure existing base table and the new one are of the same type
+ Table oldTable = getHiveTable(tablePath);
+ TableType oldTableType =
TableType.valueOf(oldTable.getTableType());
+
+ // Flink cannot alter existing Hive tables in
types that Flink cannot create for now,
+ // including EXTERNAL_TABLE, INDEX_TABLE and
MATERIALZED_VIEW.
+ // 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.
+
+ if (oldTableType == TableType.EXTERNAL_TABLE
Review comment:
1. I think the current code is better since it checks what we've supported,
what we plan to support, what we don't know (the "additional things coming in
the future" you mentioned)
2. we don't support it yet. external table has additional properties we need
to parse and check
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