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| Content Provider | Springer Nature Link |
|---|---|
| Author | Dorendorf, Stefan |
| Copyright Year | 2005 |
| Abstract | Stetig wachsende Datenmengen und hohe Verfügbarkeitsanforderungen an Datenbanken führen dazu, dass Wartungsarbeiten (wie z.B. Datenbankreorganisationen) oft nicht mehr (oder nicht mehr vollständig) offline in zur Verfügung stehenden Zeitfenstern durchgeführt werden können bzw. dass die Kosten oder die Behinderungen des normalen Datenbankbetriebs bei online durchgeführten Wartungsarbeiten nicht mehr vernachlässigt werden können. Deshalb sollte vorab bestimmt (quantifiziert) werden, ob der zu erwartende Nutzen den mit der Reorganisation verbundenen Aufwand rechtfertigt. Es ist daher wichtig, die Datenbankobjekte zu lokalisieren und einzugrenzen, bei denen ein hoher Wartungsbedarf besteht. Weiterhin ist es wünschenswert, zunächst den durch Wartungsmaßnahmen erreichbaren Nutzen vor ihrer Durchführung quantifizieren zu können. Dieser Nutzen ist auch von der Workload abhängig, also von den gegen die Datenbankobjekte gerichteten Datenbankanweisungen und deren Ausführungshäufigkeiten. Insbesondere der zur Workload-Abarbeitung anfallende I/O-Aufwand, der einen dominierenden Anteil am Gesamtaufwand ausmacht, lässt sich mit einer Datenbankreorganisation u.U. wesentlich beeinflussen (reduzieren). In diesem Beitrag wird eine Methode vorgestellt, die es ermöglicht, die Auswirkungen einer Datenbankreorganisation auf den zur Workload-Abarbeitung notwendigen I/O-Aufwand abzuschätzen und damit den hauptsächlichen Nutzen der Reorganisation zu quantifizieren. Über erste Erfahrungen mit der Methode, die anhand von Beispielen gesammelt wurden, wird berichtet.The permanent increasing amount of data and the requirement of high availability cause that maintenance of databases (e.g. database reorganizations) often is not or not completely (off-line) possible in the available time spans. On-line database reorganizations are often expensive and cumbersome during the normal database processing. To reduce performance impacts it is important to locate the database objects that have a high level of disorganization and so a high need of maintenance. Furthermore, it is desirable to be able to estimate the benefit of expensive maintenance operations before their processing. This benefit depends on the degree of disorganization and on the instructions that are processed on the database objects (workload). In particular, the costs for I/O-operations dominate the total costs for database operations. With database reorganizations it is possible to reduce the I/O-costs. In this paper we present a method to calculate the benefit of database reorganizations before the processing. The presented method allows to calculate the possible reduction of the I/O-cost for processing a given workload caused by a database reorganization. |
| Starting Page | 72 |
| Ending Page | 89 |
| Page Count | 18 |
| File Format | |
| ISSN | 01783564 |
| Journal | Informatik - Forschung und Entwicklung |
| Volume Number | 20 |
| Issue Number | 1-2 |
| e-ISSN | 09492925 |
| Language | German |
| Publisher | Springer-Verlag |
| Publisher Date | 2005-06-24 |
| Publisher Place | Berlin, Heidelberg |
| Access Restriction | Subscribed |
| Subject Keyword | Data storage representations Database administration Information storage Information search and retrieval Computer Hardware Computer Systems Organization and Communication Networks Software Engineering/Programming and Operating Systems Data Structures, Cryptology and Information Theory Theory of Computation Computer Science |
| Content Type | Text |
| Resource Type | Article |
| Subject | Computer Science |
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