DELTA: DLT-Database Synchronization

An increasingly common application for DLTs is their exploitation in enterprise systems operated by a consortium of organizations, who may assume different roles and whose interaction takes place over a blockchain network (in this scope, often permissioned), which holds a data state that they need to query frequently. In this regard, one of the main drawbacks of DLTs is their unsuitability for the efficient execution of complex queries on the data stored by the nodes comprising the network. Arising from this issue, many solutions propose to dump the ledger contents into databases, which, due to their own nature and purpose, are certainly optimized for the execution of such queries. However, most proposals on this area are not intended for querying the shared state held by the network, just the transaction history. Actually, through conducting a study on the state of the art, a lack of support for handling and querying complex structured data has been identified. DELTA provides a solution for the synchronization, with negligible overload, of the state of a DLT into a database, enabling (a) the operation with smart contracts whose data possess a complex structure and (b) the efficient execution of elaborate queries on these data. By using DELTA, query times decrease, at least, between one and five orders of magnitude, depending on the DLT, compared to queries directed to the ledger nodes.