A Cost-Aware Strategy for Merging Differential Stores in Column-Oriented In-Memory DBMS

Fast execution of analytical and transactional queries in column-oriented in-memory DBMS is achieved by combining a read-optimized data store with a write-optimized differential store. To main-tain high read performance, both structures must be merged from time to time. In this paper we describe a new merge algorithm that applies full and partial merge operations based on their costs and improvement of read performance. We show by simulation that our algorithm reduces merge costs significantly for workloads found in enterprise applications, while improving read performance at the same time.