An Algorithm for Dynamic Data Distribution, Preliminary Version
Abstract
The replication scheme of a distributed database determines how many replicas of each object are created, and to which processors these replicas are allocated. This scheme critically affects the performance of a distributed system, since reading an object locally is less costly than reading is from a remote processor. Therefore in a read-intensive network a widely distributed replication is mandated. On the other hand, an update of an object is usually written to all, or a majority of the replicas, and therefore in a write- intensive network a narrowly distributed replication is mandated. In other words, the optimal replication scheme depends on the read-write pattern for each object. Currently, the replication scheme is established in a static fashion, when the distributed-database is designed, and it remains fixed until the designer manually intervenes to change the number of replicas or their location. If the read-write patterns are fixed and are known a priori, this is a reasonable solution. However, if the read-write patterns change dynamically, in unpredictable ways, a static replication scheme may lead to severe performance problems. In this paper we propose a practical algorithm, called Dynamic-Data- Allocation (DDA), that changes the replication scheme of an object(i.e. the processors which store a replica of the object) dynamically as the read-write pattern of the object changes in the network. We assume that the changes in the read-write pattern are not known a priori.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1992
- Accession Number
- ADA252875
Entities
People
- Ouri Wolfson
- Sushil Jajodia
Organizations
- University of Illinois at Chicago