1.HAWQ 是不支持主键和外建的，官方文档明确给出
Notes
Using OIDs in new applications is not recommended. Avoid assuming that OIDs are unique across tables; if you need a database-wide unique identifier, use the combination of table OID and row OID for the purpose.
Primary key and foreign key constraints are not supported in HAWQ. For inherited tables, table privileges are not inherited in the current implementation.
HAWQ also supports the parquet columnar storage format. Parquet tables can be more efficient for increasing performance on large queries.