Two input files must be provided for a typical operation: (i) the target database of bacterial genomic sequences, which will be referred to as target database from now on, for short; and (ii) the query file, which contains a set of query genomic sequences that will be compared to the target’s database sequences for matching. As depicted in Fig. 1, SparkBLAST replicates the entire target database on every computing node. The query file is evenly partitioned into data splits which are distributed over the nodes for the execution. Thus, each computing node has a local deployment of the BLAST application, and it receives a copy of the entire target database and a set of fragments of the query file (splits). Fig. 1Data distribution among n nodes: the target database (D) is copied on every computing node; the query file (S) is evenly partitioned into data splits (S 1,…,S n) which are distributed over the nodes. Each split (S i) can be replicated on more than one node for fault tolerance