2 research outputs found
Designing Access Methods for Bitemporal Databases
By supporting the valid and transaction time dimensions, bitemporal
databases represent reality more accurately than conventional
databases. In this paper we examine the issues involved in designing
efficient access methods for bitemporal databases and propose the
partial-persistence and the double-tree methodologies. The partial-
persistence methodology reduces bitemporal queries to partial
persistence problems for which an efficient access method is then
designed. The double-tree methodology "sees" each bitemporal data
object as consisting of two intervals (a valid-time and a transaction-
time interval), and divides objects into two categories according to
whether the right endpoint of the transaction time interval is already
known. A common characteristic of both methodologies is that they
take into account the properties of each time dimension. Their
performance is compared with a straightforward approach that
"sees" the intervals associated with a bitemporal object as
composing one rectangle which is stored in a single
multidimensional access method. Given that some limited additional
space is available, our experimental results show that the partial-
persistence methodology provides the best overall performance,
especially for transaction timeslice queries. For those applications
that require ready, off-the-shelf, access methods the double-tree
methodology is a good alternative.
(Also cross-referenced as UMIACS-TR-97-24
Proposition dâun protocole expĂ©rimental pour lâĂ©valuation de performance des opĂ©rations relationnelles temporalisĂ©es
Au cours de derniĂšres anneÌes, nous avons observeÌ une croissance notable de lâutilisation des bases de donneÌes temporelles (BDT) dans divers secteurs tels que la santeÌ, lâeÌcologie, les finances et la gestion des stocks. Plusieurs solutions liĂ©es Ă la gestion du temps ont Ă©mergĂ©, chacune preÌtendant offrir des performances supeÌrieures pour manipuler dâimportantes quantitĂ©s de donnĂ©es temporelles (DT). En parcourant les pages qui suivent, le lecteur dispose de lâopportuniteÌ dâexplorer les principes fondamentaux des bases de donnĂ©es (BD), de comprendre les diffeÌrentes approches utiliseÌes dans lâinteÌgration de la temporaliteÌ dans les systĂšmes de gestion de bases de donnĂ©es (SGBD), et de comprendre les dĂ©fis liĂ©s Ă la gestion des DT. Ce mĂ©moire se penche sur la question fondamentale de lâeÌvaluation des BDT et cherche Ă offrir des voies de solution en suggĂ©rant un protocole dâeÌvaluation rigoureux afin de garantir une gestion efficace des DT dans divers domaines oĂč cette fonctionnalitĂ© est de la plus haute importance