This chapter compares the performances of a database management system based upon GDM and a DBMS based on the relational data model in terms of effective use of access paths in query processing. Performance evaluation requires the specification of storage structures, query-processing algorithms, states of schemas, and the workload of queries to be processed. The specification of storage structures is given in terms of definitions for record, index, and link storage. The state of the schema is given in terms of a set of parameters such as number of occurrences, index selection, and selectivity on attributes. The workload is a set of one-, two-, and three-variable queries. Yao’s  cost model has embedded definition of query-processing algorithms and establishes the relationships between storage structures, schema states, and query specifications. Yao’s cost model uses accesses to external storage as its cost metric. We have extended Yao’s cost model to include the algorithms necessary for processing queries against GDM.
KeywordsQuery Processing Query Evaluation Link Type Record Type Storage Structure
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