morph-GFT is an extension of morph-RDB that works with Google Fusion Table (GFT) tables. These tables can be described using R2RML Mappings and enables users to query them using SPARQL. In morph-GFT, SPARQL queries posed by users are translated into SQL-like queries that are supported by the GFT API.

Unlike standard relational database implementations normally used with R2RML, the GFT API does not support join operations. Therefore, the SQL-like queries that can be evaluated directly over the GFT API are rather simple. For this reason, we use SPARQL-DQP [2] to perform joins of intermediate results and then these intermediate results are translated using the R2RML mappings specified by the users. Using SPARQL-DQP brings another benefit: not only can we join the intermediate results from GFT tables, but also from other SPARQL endpoints.

[1] Applying SPARQL-DQP for Federated SPARQL Querying over Google Fusion Tables, Freddy Priyatna, Carlos Buil Aranda, Oscar Corcho. Extended Semantic Web Conference (ESWC 2013) demo track. link
[2] Semantics and optimization of the SPARQL 1.1 federation extension, Carlos Buil Aranda, Marcelo Arenas, Oscar Corcho. Extended Semantic Web Conference (ESWC2011), Semantic Data Management track, 2011. Best paper award. link

The morph-GFT project page is located at https://github.com/oeg-upm/morph-gft and the instructions of how to use morph-GFT can be found at https://github.com/oeg-upm/morph-gft/wiki