5. The machine-implemented method of claim 1 , further comprising: creating a representation of a connected graph based on a schema description of the relational database, tables of the relational database being represented by nodes of the connected graph, and foreign keys relating to the tables of the relational database being represented by graph edges of the connected graph, wherein the depth first search is performed by referring to the representation of the connected graph.
5. The machine-implemented method of claim 1 , further comprising: creating a representation of a connected graph based on a schema description of the relational database, tables of the relational database being represented by nodes of the connected graph, and foreign keys relating to the tables of the relational database being represented by graph edges of the connected graph, wherein the depth first search is performed by referring to the representation of the connected graph. 6. The machine-implemented method of claim 5 , wherein: the copying of previously uncopied ones of the corresponding next related table of the relational database, referred to by copied data of the corresponding previous related table of the relational database further comprises: joining a table of the shadow database corresponding to the corresponding previous related table of the relational database with the corresponding next related table of the relational database to produce matching rows from the corresponding next related table, and adding previously uncopied ones of the matching records from the corresponding next related table to a table of the shadow database corresponding to the corresponding next related table, the machine-implemented method further comprising: detecting whether the corresponding next related table is included in a loop, and attempting to find a new next related table in another branch of the connected graph when the corresponding next related table is detected as being in the detected loop and all of the produced matching rows from the corresponding next related table have already been copied to the shadow database.