In SAP HANA 2.0, dynamic tiering tables do not support foreign keys between two extended tables or between an extended table and an in-memory table. This means that if an in-memory table is part of a foreign key relationship, then it cannot be converted to an extended table in dynamic tiering until the foreign key relationship has been dropped.
Since dynamic tiering tables do not support foreign keys yet, the change from an extended table to in-memory is always possible (because extended tables would not have any foreign key attached to them), but in-memory to extended storage might be restricted due to foreign key constraints.
You can verify which tables in the TPCH
schema are part of a foreign key constraint by executing the following statement in a SQL Console:
SELECT * FROM "SYS"."REFERENTIAL_CONSTRAINTS"
WHERE SCHEMA_NAME='TPCH'
You can look at the columns: TABLE_NAME
, REFERENCED_TABLE_NAME
and CONSTRAINT_NAME
to identify which tables have the foreign key constraint on them and what the constraint is. Examples of tables that hold a foreign key constraint in this schema are ORDERS_CS
, CUSTOMER_CS
, SUPPLIER_CS
, LINEITEM_CS
, and NATION_CS
. Therefore, these tables cannot be converted to extended tables, unless the foreign key is dropped.