Figure 1
From: Hydra: a scalable proteomic search engine which utilizes the Hadoop distributed computing framework
MapReduce jobs to generate a list of peptides to score at a specified m/z ratio. The first mapper generates all possible sequences and modified sequences defined in the search parameters for a given fasta database. The reducer eliminates duplicates, remembers all source proteins and emits the peptide with m/z as the key. The next set of reducers collects all peptides to be scored against a given m/z and stores them in the database.