The Experts below are selected from a list of 11313 Experts worldwide ranked by ideXlab platform
Federica Mandreoli - One of the best experts on this subject based on the ideXlab platform.
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A formal model for temporal Schema versioning in object-oriented databases
Data & Knowledge Engineering, 2003Co-Authors: Fabio Grandi, Federica MandreoliAbstract:In this paper we present a formal model for the support of temporal Schema versions in object-oriented databases. Its definition is partially based on a generic (ODMG compatible) object model and partially introduces new concepts. The proposed model supports all the Schema changes which are usually considered in the OODB literature, for which an operational semantics and a formal analysis of their correct behaviour is provided. Semantic issues arising from the introduction of temporal Schema versioning in a conventional or temporal database (concerning the interaction between the intensional and extensional levels of versioning and the management of data in the presence of Multiple Schema versions) are also considered.
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A Formal Model for Temporal Schema Versioning in Object-Oriented Databases
2002Co-Authors: Fabio Grandi, Federica MandreoliAbstract:The problem of supporting temporal Schema versioning has been extensively studied in the context of the relational model. In the object-oriented environment, previous works were devoted to the study of the different aspects of Schema evolution or (non-temporal) versioning in branching models, due to the traditional origination of the object-oriented model from CAD/CAM and CIM. Nowadays, the common use of the object-oriented model for a wide class of applications, extends temporal versioning requirements and expectations also to this model. In this paper we present a formal model for the support of temporal Schema versions in objectoriented databases. Its definition is partially based on a generic (ODMG compatible) object model and partially introduces new concepts. The proposed model supports all the Schema changes which are usually considered in the OODB literature, for which an operational semantics and a formal analysis of their correct behaviour is provided. Semantic issues arising from the introduction of temporal Schema versioning in a conventional or temporal database (concerning the interaction between the intensional and extensional levels of versioning and the management of data in the presence of Multiple Schema versions) are also considered
Fabio Grandi - One of the best experts on this subject based on the ideXlab platform.
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A formal model for temporal Schema versioning in object-oriented databases
Data & Knowledge Engineering, 2003Co-Authors: Fabio Grandi, Federica MandreoliAbstract:In this paper we present a formal model for the support of temporal Schema versions in object-oriented databases. Its definition is partially based on a generic (ODMG compatible) object model and partially introduces new concepts. The proposed model supports all the Schema changes which are usually considered in the OODB literature, for which an operational semantics and a formal analysis of their correct behaviour is provided. Semantic issues arising from the introduction of temporal Schema versioning in a conventional or temporal database (concerning the interaction between the intensional and extensional levels of versioning and the management of data in the presence of Multiple Schema versions) are also considered.
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A Formal Model for Temporal Schema Versioning in Object-Oriented Databases
2002Co-Authors: Fabio Grandi, Federica MandreoliAbstract:The problem of supporting temporal Schema versioning has been extensively studied in the context of the relational model. In the object-oriented environment, previous works were devoted to the study of the different aspects of Schema evolution or (non-temporal) versioning in branching models, due to the traditional origination of the object-oriented model from CAD/CAM and CIM. Nowadays, the common use of the object-oriented model for a wide class of applications, extends temporal versioning requirements and expectations also to this model. In this paper we present a formal model for the support of temporal Schema versions in objectoriented databases. Its definition is partially based on a generic (ODMG compatible) object model and partially introduces new concepts. The proposed model supports all the Schema changes which are usually considered in the OODB literature, for which an operational semantics and a formal analysis of their correct behaviour is provided. Semantic issues arising from the introduction of temporal Schema versioning in a conventional or temporal database (concerning the interaction between the intensional and extensional levels of versioning and the management of data in the presence of Multiple Schema versions) are also considered
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Schema versioning for multitemporal relational databases
Information Systems, 1997Co-Authors: Cristina De Castro, Fabio Grandi, Maria Rita ScalasAbstract:In order to follow the evolution of application needs, a database management system is easily expected to undergo changes involving database structure after implementation. Schema evolution concerns the ability of maintaining extant data in response to changes in database structure. Schema versioning enables the use of extensional data through Multiple Schema interfaces as created by a history of Schema changes. However, Schema versioning has been considered only to a limited extent in current literature. Also in the field of temporal databases, whereas a great deal of work has been done concerning temporal versioning of extensional data, a thorough investigation of Schema versioning potentialities has not yet been made. In this paper we consider Schema versioning in a broader perspective and introduce new design options whose distinct semantic properties and functionalities will be discussed. First of all, we consider solutions for Schema versioning along transaction time but also along valid time. Moreover, the support of Schema versioning implies operations both at intensional and extensional level. Two distinct design solutions (namely single- and multi-pool) are presented for the management of extensional data in a system supporting Schema versioning. Finally, a further distinction is introduced to define synchronous and asynchronous management of versioned data and Schemata. The proposed solutions differ in their semantics and in the possible operations they support. The mechanisms for the selection of data through a Schema version are in many cases strictly related to the particular Schema versioning solution adopted, that also affects the data definition and manipulation language at user-interface level. In particular, we show how the temporal language TSQL2, originally designed to support basic functionalities of transaction-time Schema versioning, can accordingly be extended. © 1997 Elsevier Science Ltd.
Gottfried Vossen - One of the best experts on this subject based on the ideXlab platform.
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Schema versioning in data warehouses enabling cross version querying via Schema augmentation
Data and Knowledge Engineering, 2006Co-Authors: Matteo Golfarelli, Jens Lechtenborger, Stefano Rizzi, Gottfried VossenAbstract:As several mature implementations of data warehousing systems are fully operational, a crucial role in preserving their up-to-dateness is played by the ability to manage the changes that the data warehouse (DW) Schema undergoes over time in response to evolving business requirements. In this paper we propose an approach to Schema versioning in DWs, where the designer may decide to undertake some actions on old data aimed at increasing the flexibility in formulating cross-version queries, i.e., queries spanning Multiple Schema versions. First, we introduce a representation of DW Schemata as graphs of simple functional dependencies, and discuss its properties. Then, after defining an algebra of Schema graph modification operations aimed at creating new Schema versions, we discuss how augmented Schemata can be introduced to increase flexibility in cross-version querying. Next, we show how a history of versions for DW Schemata is managed and discuss the relationship between the temporal horizon spanned by a query and the Schema on which it can consistently be formulated.
Matteo Golfarelli - One of the best experts on this subject based on the ideXlab platform.
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Schema versioning in data warehouses enabling cross version querying via Schema augmentation
Data and Knowledge Engineering, 2006Co-Authors: Matteo Golfarelli, Jens Lechtenborger, Stefano Rizzi, Gottfried VossenAbstract:As several mature implementations of data warehousing systems are fully operational, a crucial role in preserving their up-to-dateness is played by the ability to manage the changes that the data warehouse (DW) Schema undergoes over time in response to evolving business requirements. In this paper we propose an approach to Schema versioning in DWs, where the designer may decide to undertake some actions on old data aimed at increasing the flexibility in formulating cross-version queries, i.e., queries spanning Multiple Schema versions. First, we introduce a representation of DW Schemata as graphs of simple functional dependencies, and discuss its properties. Then, after defining an algebra of Schema graph modification operations aimed at creating new Schema versions, we discuss how augmented Schemata can be introduced to increase flexibility in cross-version querying. Next, we show how a history of versions for DW Schemata is managed and discuss the relationship between the temporal horizon spanned by a query and the Schema on which it can consistently be formulated.
Jens Lechtenborger - One of the best experts on this subject based on the ideXlab platform.
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Schema versioning in data warehouses enabling cross version querying via Schema augmentation
Data and Knowledge Engineering, 2006Co-Authors: Matteo Golfarelli, Jens Lechtenborger, Stefano Rizzi, Gottfried VossenAbstract:As several mature implementations of data warehousing systems are fully operational, a crucial role in preserving their up-to-dateness is played by the ability to manage the changes that the data warehouse (DW) Schema undergoes over time in response to evolving business requirements. In this paper we propose an approach to Schema versioning in DWs, where the designer may decide to undertake some actions on old data aimed at increasing the flexibility in formulating cross-version queries, i.e., queries spanning Multiple Schema versions. First, we introduce a representation of DW Schemata as graphs of simple functional dependencies, and discuss its properties. Then, after defining an algebra of Schema graph modification operations aimed at creating new Schema versions, we discuss how augmented Schemata can be introduced to increase flexibility in cross-version querying. Next, we show how a history of versions for DW Schemata is managed and discuss the relationship between the temporal horizon spanned by a query and the Schema on which it can consistently be formulated.
