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A Foundation for Conventional and Temporal Query Optimization Addressing Duplicates and Ordering
- IEEE TKDE
, 2001
"... AbstractÐMost real-world databases contain substantial amounts of time-referenced, or temporal, data. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in temporal support in the DBMS. To achieve this, temporal query representation, ..."
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Cited by 10 (2 self)
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AbstractÐMost real-world databases contain substantial amounts of time-referenced, or temporal, data. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in temporal support in the DBMS. To achieve this, temporal query representation, optimization, and processing mechanisms must be provided. This paper presents a foundation for query optimization that integrates conventional and temporal query optimization and is suitable for both conventional DBMS architectures and ones where the temporal support is obtained via a layer on top of a conventional DBMS. This foundation captures duplicates and ordering for all queries, as well as coalescing for temporal queries, thus generalizing all existing approaches known to the authors. It includes a temporally extended relational algebra to which SQL and temporal SQL queries may be mapped, six types of algebraic equivalences, concrete query transformation rules that obey different equivalences, a procedure for determining which types of transformation rules are applicable for optimizing a query, and a query plan enumeration algorithm. The presented approach partitions the work required by the database implementor to develop a provably correct query optimizer into four stages: The database implementor has to 1) specify operations formally, 2) design and prove correct appropriate transformation rules that satisfy any of the six equivalence types, 3) augment the mechanism that determines when the different types of rules are applicable to ensure that the enumeration algorithm applies the rules correctly, and 4) ensure that the mapping generates a correct initial query plan. Index TermsÐTemporal databases, query optimization, transformation rules, temporal algebra, duplicate elimination, coalescing. 1
Adaptable Query Optimization and Evaluation in Temporal Middleware
, 2001
"... Time-referenced data are pervasive in most real-world databases. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in temporal support in the DBMS. To achieve this, temporal query optimization and evaluation mechanisms must be pro ..."
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Cited by 5 (3 self)
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Time-referenced data are pervasive in most real-world databases. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in temporal support in the DBMS. To achieve this, temporal query optimization and evaluation mechanisms must be provided, either within the DBMS proper or as a source level translation from temporal queries to conventional SQL. This paper proposes a new approach: using a middleware component on top of a conventional DBMS. This component accepts temporal SQL statements and produces a corresponding query plan consisting of algebraic as well as regular SQL parts. The algebraic parts are processed by the middleware, while the SQL parts are processed by the DBMS. The middleware uses performance feedback from the DBMS to adapt its partitioning of subsequent queries into middleware and DBMS parts. The paper describes the architecture and implementation of the temporal middleware component, termed TANGO, which is based on the Volcano extensible query optimizer and the XXL query processing library. Experiments with the system demonstrate the utility of the middleware`s internal processing capability and its cost-based mechanism for apportioning the processing between the middleware and the underlying DBMS. Index terms: temporal databases, query processing and optimization, cost-based optimization, middleware 1
A comparison of two approaches to utilizing XML in parametric databases for temporal data
- Information & Software Technology
, 2006
"... The parametric data model captures an object in terms of a single tuple. This feature eliminates unnecessary self-join operations to combine tuples scattered in a temporal relation. Despite this advantage, this model is relatively difficult to implement on top of relational databases because the siz ..."
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The parametric data model captures an object in terms of a single tuple. This feature eliminates unnecessary self-join operations to combine tuples scattered in a temporal relation. Despite this advantage, this model is relatively difficult to implement on top of relational databases because the sizes of attributes are un-fixed. Since data boundaries are not problematic in XML, XML can be an elegant solution to implement parametric databases for temporal data. There are two approaches to implementing parametric databases using XML: 1) a native XML database with XQuery engine, and 2) an XML storage with a temporal query lan-guage. To determine which approach is appropriate in parametric databases, we consider four questions: the effectiveness of XML in modeling temporal data, the applicability of XML query languages, the user-friendliness of the query languages, and system performances of two approaches. By evaluating the four questions, we show that the latter approach is more appropriate to utilizing XML in parametric
Natural and Efficient Modeling of Temporal Information with Object-Relational Databases
"... In this article we present a model for temporal data utilizing the benefits of object-relational database systems (ORDBS). In particular we show how attribute timestamping can be used for natural modeling of object attributes on the conceptual level and how this concept can be simply and efficiently ..."
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In this article we present a model for temporal data utilizing the benefits of object-relational database systems (ORDBS). In particular we show how attribute timestamping can be used for natural modeling of object attributes on the conceptual level and how this concept can be simply and efficiently implemented in state-of-the-art ORDBS. The attribute timestamping concept is based on introducing temporal versions of datatypes; it is translated into a logical and then into a physical model making use of the possibility to define user-specific types in ORDBS. Moreover on the physical level we make use of another feature of ORDBS: the definition of user-defined index structures; in particular adapted spatial indexes based on generalized search trees are applied. These index structures are then used to greatly improve performance of important temporal operators on the temporal datatypes. The experiments were carried out for valid time as well as bitemporal attributes and show the effectiveness of this approach.
A Middleware Approach to Temporal Query Processing
, 2001
"... Time-referenced, or temporal, data occur pervasively in most real-world databases. Recent advances in temporal query languages show that such applications may benefit substantially from a database management system (DBMS) with built-in temporal support. The potential benefits are several: applicatio ..."
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Time-referenced, or temporal, data occur pervasively in most real-world databases. Recent advances in temporal query languages show that such applications may benefit substantially from a database management system (DBMS) with built-in temporal support. The potential benefits are several: application code is simplified and more easily maintainable, thereby increasing programmer productivity, and more data processing can be left to the DBMS, potentially leading to better performance. In contrast, the built-in temporal support offered by current database products is limited to predefined, time-related data types, e.g., the Informix TimeSeries DataBlade and the Oracle TimeSeries cartridge, and extensibility facilities that enable the user to define new, e.g., temporal, data types. However, temporal support is needed that goes beyond data types and extends the query language itself, as well as integrates temporal operations into the query optimization and processing framework. This Ph.D. thesis presents an algebraic foundation for temporal query representation, optimization, and processing, as well as an implementation of the foundation in a layered architecture. The foundation includes an algebra for temporal query representation, a comprehensive set of transformation rules, and a query plan enumeration algorithm. The algebra enhances existing relational algebras based on multisets by integrating the handling of order and adding temporal support, and the transformation rules are divided into different types according to how they deal with duplicates, order, and time periods. By capturing duplicate removal and retention and order preservation for all queries, as well as coalescing for temporal queries, the foundation formalizes and generalizes existing approaches. The found...
Performance of Querying Temporal Attributes in Object-Relational Databases
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Implementing Parameterized Range Types in an Extensible DBMS *
"... Abstract A parameterized type defines a family of related types. For example, a single parameterized type ARRAY provides a common definition for array of INTEGER, array of FLOAT, and array of rows of a certain row type. SQL3 proposes support for user-defined parameterized types (or UDPTs for short) ..."
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Abstract A parameterized type defines a family of related types. For example, a single parameterized type ARRAY provides a common definition for array of INTEGER, array of FLOAT, and array of rows of a certain row type. SQL3 proposes support for user-defined parameterized types (or UDPTs for short), but we have yet to see any full implementation in a commercial DBMS. In this paper, we show how we implemented UDPTs Range and RangeSet using the DataBlade and Fastpath extensibility features of Informix. We also describe the application of these UDPTs in building a temporal database with TSQL2-like features. We found that implementing temporal database primitives using UDPTs required much less development effort and is more flexible than our earlier approach that used regular, non-parameterized user-defined types. We report some lessons learned in the implementation process, and propose a "wish list" of DBMS extensibility features required for full support of UDPTs. Although our implementation is based on Informix, we expect our experience and findings to be relevant to anyone implementing UDPTs in an extensible DBMS.
ABSTRACT Adaptable Query Optimization and Evaluation in Temporal Middleware
"... Time-referenced data are pervasive in most real-world databases. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in temporal support in the DBMS. To achieve this, temporal query optimization and evaluation mechanisms must be provi ..."
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Time-referenced data are pervasive in most real-world databases. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in temporal support in the DBMS. To achieve this, temporal query optimization and evaluation mechanisms must be provided, either within the DBMS proper or as a source level translation from temporal queries to conventional SQL. This paper proposes a new approach: using a middleware component on top of a conventional DBMS. This component accepts temporal SQL statements and produces a corresponding query plan consisting of algebraic as well as regular SQL parts. The algebraic parts are processed by the middleware, while the SQL parts are processed by the DBMS. The middleware uses performance feedback from the DBMS to adapt its partitioning of subsequent queries into middleware and DBMS parts. The paper describes the architecture and implementation of the temporal middleware component, termed TANGO, which is based on the Volcano extensible query optimizer and the XXL query processing library. Experiments with the system demonstrate the utility of the middleware‘s internal processing capability and its cost-based mechanism for apportioning the processing between the middleware and the underlying DBMS. 1.
Research Article BtSQL: nested bitemporal relational database query language
"... Abstract: A nested bitemporal relational data model and its query language are implemented. The bitemporal atom (BTA) is the fundamental construct to represent temporal data and it contains 5 components: a value, the lower and upper bounds of valid time, and the lower and upper bounds of the recodin ..."
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Abstract: A nested bitemporal relational data model and its query language are implemented. The bitemporal atom (BTA) is the fundamental construct to represent temporal data and it contains 5 components: a value, the lower and upper bounds of valid time, and the lower and upper bounds of the recoding time. We consider 2 types of data structures for storing BTAs: 1) string representation and 2) abstract data-type representation. We also develop a preprocessor for translating a bitemporal structured query language (BtSQL) statement into standard SQL statements. The BtSQL includes the select, insert, delete, and update statements of the SQL, extended for bitemporal relational databases. It supports bitemporal, historical, and current context. Bitemporal context is for auditing purposes, historical context is for querying past states of a bitemporal database, and current context is for querying the snapshot state of a bitemporal database. We also evaluate the performance of the 2 alternative implementation methods by considering retrieval, insertion, and update queries. Key words: Bitemporal database, nested bitemporal relational model, bitemporal atom type, bitemporal query, BtSQL 1.
