Support for Schema Evolution in Data Stream Management Systems
            
            
               James F. Terwilliger (Microsoft Corporation, USA)  
              
             
            
            
               Rafael J. Fernández-Moctezuma (Portland State University, USA)  
              
             
            
            
               Lois M. L. Delcambre (Portland State University, USA)  
              
             
            
            
               David Maier (Portland State University, USA)  
              
             
                    
            
              Abstract: Unlike Database Management Systems (DBMSs), Data Stream Management Systems (DSMSs) do not evaluate queries over static data sets — rather, they continuously produce result streams to standing queries, and often operate in a context where any interruption can lead to data loss. Support for schema evolution in such an environment is currently unaddressed. In this work we address evolution in DSMSs by introducing a new element to streams, called an accent, that precedes and describes an evolution. We characterize how a subset of commonly used query operators in DSMS act on and propagate accents with respect to three evolution primitives: Add Attribute, Drop Attribute, and Alter Data. 
             
            
              Keywords: data streams, schema evolution 
             
            Categories: H.2.1, H.2.4, H.2.8  
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