Authors:
            
                    Leonardo Guerreiro Azevedo
                    
                        
                    
                    ; 
                
                    Elton Figueiredo de Souza Soares
                    
                        
                    
                    ; 
                
                    Renan Souza
                    
                        
                    
                     and
                
                    Marcio Ferreira Moreno
                    
                        
                    
                    
                
        
        
            Affiliation:
            
                    
                        
                    
                    IBM Research, Brazil
                
        
        
        
        
        
             Keyword(s):
            Federated Database, Polyglot Database, Multistore, Polystore, Multidatabase, Heterogeneous Data Stores, NoSQL, Dbaas, Distributed File System, Data Processing Frameworks.
        
        
            
                
                
            
        
        
            
                Abstract: 
                Usually, modern applications manipulate datasets with diverse models, usages, and storages. “One size fits all” approaches are not sufficient for heterogeneous data, storages, and schemes. The rise of new kinds of data stores and processing, like NoSQL data stores, distributed file systems, and new data processing frameworks, brought new possibilities to meet this scenario’s requirements. However, semantic, schema and storage heterogeneity, autonomy, and distributed processing are still among the main concerns when building data-driven applications. This work surveys the literature aiming at giving an overview of the state of the art of modern federated database systems. It presents the background, characterizes existing tools, depicts guidelines one should follow when creating solutions, and points out research challenges to consider in future work. This work gives fundamentals for researchers and practitioners in the area.