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TableEnvironment#from(descriptor) will register descriptor under a system generated table path (just like TableImpl#toString) first, and scan from the table path to derive the Tablecreate a specific QueryOperation and will be converted to scan RelNode later in QueryOperationConverter. Table#executeInsert() does it in the similar way will create a specific ModifyOperation and will be converted to sink RelNode later in PlannerBase. 

Compatibility, Deprecation, and Migration Plan

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