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Partial Match Retrieval in Two-headed Disks
| Content Provider | CiteSeerX |
|---|---|
| Author | Manolopoutos, Yannis Vakali, Athena |
| Abstract | Abstract. The performance of a disk with two heads per surface sepa-rated by a fixed number of cylinders is examined. We derive the proba-bility distribution of arm stops, the expected number of stops as well as the expected number of cylinder clusters, i.e. the number of sets of con-secutive compound cylinders. In comparison with a single-headed disk, it is shown that the performance gain may reach 50 % on the average. 1 In t roduct ion According to the problem of partial match retrieval, the aim is to group the file records into pages to facilitate partial match queries in such a way that queries are answered by accessing the minimal number of pages on the average [15]. On the other hand, according to the problem of multidisk files, the purpose is to allocate the file pages to specific disks in order to exploit the fact that the disks may be accessed concurrently [6]. Since the multidisk file problem has been proven to be NP-hard, the effort is directed towards proposing an efficient heuristic. The known heuristics can be summarized in three categories:- the Random Data Allocation and the Partition Data Allocation methods,- the Modulo Allocation methods, such as the Disk Modulo [6], the Generalized |
| File Format | |
| Access Restriction | Open |
| Subject Keyword | Partial Match Retrieval Two-headed Disk Expected Number Disk Modulo Cylinder Cluster File Record Specific Disk Random Data Allocation Con-secutive Compound Cylinder Known Heuristic Roduct Ion File Page Efficient Heuristic Fixed Number Multidisk File Multidisk File Problem Modulo Allocation Method Partial Match Query Performance Gain Proba-bility Distribution Arm Stop Partition Data Allocation Method Minimal Number Single-headed Disk |
| Content Type | Text |
| Resource Type | Article |
