Abstract: A computer-implemented method for generating a summary of a graph database comprising a set of RDF tuples including obtaining the graph database and generating a summary having a set of probabilistic filters. Each probabilistic filter of the set determines if at least one RDF tuple existing in the graph database corresponds to a respective basic graph pattern of the probabilistic filter with a possibility of false positive.

Abstract: A computer-implemented method for storing a database state. The method comprises providing a database, receiving by the database one or more write events, logging each write event, each logged write event thus forming a new state on the database, buffering pages modified or created by the write events, and creating a patch by flushing to a database storage the buffered pages if a threshold has been met.

Abstract: A computer-implemented method for querying by a query engine on a database including relational data and graph data, the method including receiving a query by the query engine, the query being in a language compatible with a first order logic paradigm. The method further includes generating an intermediate representation, the IR being compatible with a first order logic paradigm. The method further includes using the intermediate representation of the query for executing the query on the relational data and the graph data of the database.

Abstract: A method for compressing RDF tuples. The method including obtaining RDF tuples, obtaining a dictionary of indices, encoding for each RDF tuple the indices attributed to the subject and the object, grouping RDF tuples sharing the same predicate and for each group sorting the RDF tuples by considering the encoding of the subject and the object, and for each group of sorted RDF tuples, serializing the index of the shared predicate, serializing the encoding of the subject and the object of a first RDF tuple, and for each RDF tuple of the group of sorted RDF tuples subsequent to the first RDF tuple of the group, computing a difference between the encoding of the subject and the object of a current RDF tuple and the encoding of the subject and the object of a previous RDF tuple, and serializing the computed difference in a form of a variable-length integer.

Abstract: A method for compressing RDF tuples. The method including obtaining RDF tuples, obtaining a dictionary of indices, encoding for each RDF tuple the indices attributed to the subject and the object, grouping RDF tuples sharing the same predicate and for each group sorting the RDF tuples by considering the encoding of the subject and the object, and for each group of sorted RDF tuples, serializing the index of the shared predicate, serializing the encoding of the subject and the object of a first RDF tuple, and for each RDF tuple of the group of sorted RDF tuples subsequent to the first RDF tuple of the group, computing a difference between the encoding of the subject and the object of a current RDF tuple and the encoding of the subject and the object of a previous RDF tuple, and serializing the computed difference in a form of a variable-length integer.

Abstract: A method for compressing RDF tuples. The method including obtaining RDF tuples, obtaining a dictionary of indices, encoding for each RDF tuple the indices attributed to the subject and the object, grouping RDF tuples sharing the same predicate and for each group sorting the RDF tuples by considering the encoding of the subject and the object, and for each group of sorted RDF tuples, serializing the index of the shared predicate, serializing the encoding of the subject and the object of a first RDF tuple, and for each RDF tuple of the group of sorted RDF tuples subsequent to the first RDF tuple of the group, computing a difference between the encoding of the subject and the object of a current RDF tuple and the encoding of the subject and the object of a previous RDF tuple, and serializing the computed difference in a form of a variable-length integer.

Abstract: A method for compressing RDF tuples. The method including obtaining RDF tuples, obtaining a dictionary of indices, encoding for each RDF tuple the indices attributed to the subject and the object, grouping RDF tuples sharing the same predicate and for each group sorting the RDF tuples by considering the encoding of the subject and the object, and for each group of sorted RDF tuples, serializing the index of the shared predicate, serializing the encoding of the subject and the object of a first RDF tuple, and for each RDF tuple of the group of sorted RDF tuples subsequent to the first RDF tuple of the group, computing a difference between the encoding of the subject and the object of a current RDF tuple and the encoding of the subject and the object of a previous RDF tuple, and serializing the computed difference in a form of a variable-length integer.

Abstract: A computer-implemented method for updating a virtual RDF graph database, the virtual database comprising tuples including a file storage having a durability property of ACID property and guarantying consistent write, providing a virtual RDF graph database including a first RDF graph database updatable by streams and a second read-only RDF graph database stored on the file storage and updatable by batches, a catalog for storing metadata describing the second read-only RDF graph database on the file storage, the catalog being compliant with ACID and obtaining a stream of tuples and a batch of tuples, applying the stream of tuples on the first RDF graph database, applying the batch of tuples on the second RDF graph database by computing a snapshot of the second RDF graph database, including the batch of tuples, the computed snapshot and registering the computed snapshot in the catalog.

Abstract: A computer-implemented read-only data structure for archiving a snapshot of a RDF dataset into a file, the RDF dataset comprising one or more graphs, the read-only data structure that can be directly queried using all possible triple patterns of a SPARQL query engine. The data structure comprises an indexed list of the one or more graphs of the RDF dataset, for each graph of the RDF dataset, an indexed list of predicates, a dictionary mapping each RDF term of the dataset to a respective index and inversely, and for each predicate indexed in the indexed list of predicates of each graph, an adjacency matrix representing a group of tuples of the RDF dataset, thereby obtaining a complete representation of the RDF dataset that can be directly queried using all possible triple patterns of a SPARQL query engine.

Abstract: A computer-implemented method for querying by a query engine on a database including relational data and graph data, the method including receiving a query by the query engine, the query being in a language compatible with a first order logic paradigm. The method further includes generating an intermediate representation, the IR being compatible with a first order logic paradigm. The method further includes using the intermediate representation of the query for executing the query on the relational data and the graph data of the database.

Abstract: A computer-Implemented method of storing RDF graph data in a graph database including a set of RDF tuples. The method includes obtaining one or more adjacency matrices wherein each adjacency matrix represents a group of tuples of the graph database comprising a same predicate. The method further includes storing, for each of the one or more adjacency matrices, a data structure includes an array. The array includes one or more indices each pointing to a sub-division of the adjacency matrix, and/or one or more elements each representing a group of tuples of the RDF graph database of a respective sub-division of the adjacency matrix.

Abstract: A computer-implemented method for generating a summary of a graph database comprising a set of RDF tuples including obtaining the graph database and generating a summary having a set of probabilistic filters. Each probabilistic filter of the set determines if at least one RDF tuple existing in the graph database corresponds to a respective basic graph pattern of the probabilistic filter with a possibility of false positive.

Abstract: A computer implemented method for creating a tree of database states including accessing a database having at least one branch of database states, receiving at the database one or more write events that are applied to an identified state of the database, recovering the identified database state from the database, creating a new branch by creating a new patch as alternative state to the identified database state with a reference to the identified state.

Abstract: A computer implemented method for creating a tree of database states including accessing a database having at least one branch of database states, receiving at the database one or more write events that are applied to an identified state of the database, recovering the identified database state from the database, creating a new branch by creating a new patch as alternative state to the identified database state with a reference to the identified state.

Abstract: A computer-implemented method for storing a database state. The method comprises providing a database, receiving by the database one or more write events, logging each write event, each logged write event thus forming a new state on the database, buffering pages modified or created by the write events, and creating a patch by flushing to a database storage the buffered pages if a threshold has been met.