Logical Operators

Logical plans of HeFQUIN are FedQPL expressions^[1]. Hence, the logical operators that HeFQUIN uses are the FedQPL operators. The main interface for these operators is called LogicalOperator. Their implementations can be found in the se.liu.ida.hefquin.engine.queryplan.logical.impl package and include:

Nullary Operators

• LogicalOpRequest (req)

Unary Operators

• LogicalOpTPAdd (tpAdd)
• LogicalOpTPOptAdd (tpOptAdd)
• LogicalOpBGPAdd (bgpAdd)
• LogicalOpBGPOptAdd (bgpOptAdd)
• LogicalOpGPAdd (gpAdd)
• LogicalOpGPOptAdd (gpOptAdd)
• LogicalOpFilter (filter)
• LogicalOpGlobalToLocal (g2l)
• LogicalOpLocalToGlobal (l2g)

Binary Operators

• LogicalOpJoin (join)
• LogicalOpRightJoin (rightjoin)
• LogicalOpUnion (union)

N-ary Operators

• LogicalOpMultiwayJoin (mj)
• LogicalOpMultiwayLeftJoin (mlj)
• LogicalOpMultiwayUnion (mu)

^[1] Sijin Cheng and Olaf Hartig: FedQPL: A Language for Logical Query Plans over Heterogeneous Federations of RDF Data Sources. In Proceedings of the 22nd International Conference on Information Integration and Web-based Applications & Services (iiWAS), 2020.