19. The method of claim 12 , wherein the graph query involves iterative processing on the graph, the method further comprising: obtaining topology knowledge on the graph, the topology knowledge being isolated from the relational database; and optimizing the iterative processing at least in part based on the topology knowledge.
12. A computer-implemented method comprising: receiving a graph query on data representing a graph including a plurality of nodes, the graph query involving a traversal from a source node to a sink node that is adjacent to the source node; converting the graph query into a structured query language (SQL) query over the first table and a second table; retrieving, from a source table in a relational database, a record corresponding to the source node, the record containing a multi-valued field that stores a multi-valued non-local property of the source node, the multi-valued non-local property including a reference to at least one adjacent node of the source node; obtaining, based on the multi-valued non-local property of the source node, data of the sink node from a sink table with the SQL query; storing, for each node in the graph, an adjacency list in the multi-valued field, the adjacency list containing the reference to the at least one adjacent node; transforming the adjacency list to a temporary table; and using the temporary table to locate the corresponding record.