External Memory PDBs: Initial Results

Pattern databases (PDBs) have been widely used as heuristics for many types of search spaces, but they have always been computed so as to fit in the main memory of the machine using the PDB. This paper studies the how external-memory PDBs can be used. It presents results of both using hard disk drives and solid-state drives directly to access the data, and of just loading a portion of the PDB into RAM. For the time being, all of these approaches are inferior to building the largest PDB that fits into RAM.