Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655816
S. Banerjee, Panos K. Chrysanthis
The advent of high-speed networks will enable the deployment of data-server systems (currently used in LANs) over WANs. The users of these systems will have the same high expectations with respect to performance parameters (such as the transaction throughput, response time and system reliability) as in the case of LANs. Thus, it is important to study the performance of existing distributed database protocols in the new networking environment, identify the performance bottlenecks and develop protocols that are capable of taking advantage of the high-speed networking technology. As a first step, in this paper, we examine the scalability of the server-based two-phase locking (s-2PL) protocol, and discuss three optimizations which allow the s-2PL protocol to be tailored for high-speed WAN environments where the size of the message is less of a concern than the number of rounds of message passing. These optimizations, collectively called the group two-phase locking (g-2PL) protocol, reduce the number of rounds of message passing by grouping lock grants, client-end caching and data migration. In a simulation study, 20-25% improvement in the response time of the g-2PL protocol over that of the s-2PL protocol was observed.
{"title":"Network latency optimizations in distributed database systems","authors":"S. Banerjee, Panos K. Chrysanthis","doi":"10.1109/ICDE.1998.655816","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655816","url":null,"abstract":"The advent of high-speed networks will enable the deployment of data-server systems (currently used in LANs) over WANs. The users of these systems will have the same high expectations with respect to performance parameters (such as the transaction throughput, response time and system reliability) as in the case of LANs. Thus, it is important to study the performance of existing distributed database protocols in the new networking environment, identify the performance bottlenecks and develop protocols that are capable of taking advantage of the high-speed networking technology. As a first step, in this paper, we examine the scalability of the server-based two-phase locking (s-2PL) protocol, and discuss three optimizations which allow the s-2PL protocol to be tailored for high-speed WAN environments where the size of the message is less of a concern than the number of rounds of message passing. These optimizations, collectively called the group two-phase locking (g-2PL) protocol, reduce the number of rounds of message passing by grouping lock grants, client-end caching and data migration. In a simulation study, 20-25% improvement in the response time of the g-2PL protocol over that of the s-2PL protocol was observed.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125393159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655770
E. Gabber, H. F. Korth
RAIDs (Redundant Arrays of Independent Disks) are a set of disks organized to achieve parallel I/O to multiple disks and to provide tolerance of disk failures. RAIDs offer these advantages at the cost of additional space and additional disk I/O for writes. Previous methods of reducing this I/O overhead suffered from such problems as requiring periods during which data is reorganized and not available, destroying the physical locality of data, or weakening the RAID's fault-tolerance properties. We propose a new method called data logging which reduces the I/O overhead without requiring periodic downtime for reorganization. Instead, incremental maintenance can be performed concurrently with routine processing. This is particularly advantageous in applications requiring "24/spl times/7" uptime. Data logging preserves both physical locality of data and RAID fault tolerance. The major cost of our method is a moderate amount of nonvolatile RAM. This paper describes our method, as well as two schemes for efficient encoding of the information that must be stored in nonvolatile RAM.
{"title":"Data logging: a method for efficient data updates in constantly active RAIDs","authors":"E. Gabber, H. F. Korth","doi":"10.1109/ICDE.1998.655770","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655770","url":null,"abstract":"RAIDs (Redundant Arrays of Independent Disks) are a set of disks organized to achieve parallel I/O to multiple disks and to provide tolerance of disk failures. RAIDs offer these advantages at the cost of additional space and additional disk I/O for writes. Previous methods of reducing this I/O overhead suffered from such problems as requiring periods during which data is reorganized and not available, destroying the physical locality of data, or weakening the RAID's fault-tolerance properties. We propose a new method called data logging which reduces the I/O overhead without requiring periodic downtime for reorganization. Instead, incremental maintenance can be performed concurrently with routine processing. This is particularly advantageous in applications requiring \"24/spl times/7\" uptime. Data logging preserves both physical locality of data and RAID fault tolerance. The major cost of our method is a moderate amount of nonvolatile RAM. This paper describes our method, as well as two schemes for efficient encoding of the information that must be stored in nonvolatile RAM.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115083379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655819
Chitta Baral, G. Gonzalez, Tran Cao Son
We present the design and implementation of a loosely-bound SQL extension that allows users to include high-level display specifications with an SQL query, particularly when dealing with multimedia databases. We describe an architecture that allows a relatively simple implementation of dynamic query browsers using the proposed query language on stand-alone applications or World Wide Web pages. We have already implemented most of our proposed extension.
{"title":"Design and implementation of display specification for multimedia answers","authors":"Chitta Baral, G. Gonzalez, Tran Cao Son","doi":"10.1109/ICDE.1998.655819","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655819","url":null,"abstract":"We present the design and implementation of a loosely-bound SQL extension that allows users to include high-level display specifications with an SQL query, particularly when dealing with multimedia databases. We describe an architecture that allows a relatively simple implementation of dynamic query browsers using the proposed query language on stand-alone applications or World Wide Web pages. We have already implemented most of our proposed extension.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123037152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655809
Nick Koudas, K. Sevcik
Current data repositories include a variety of data types, including audio, images and time series. State of the art techniques for indexing such data and doing query processing rely on a transformation of data elements into points in a multidimensional feature space. Indexing and query processing then take place in the feature space. We study algorithms for finding relationships among points in multidimensional feature spaces, specifically algorithms for multidimensional joins. Like joins of conventional relations, correlations between multidimensional feature spaces can offer valuable information about the data sets involved. We present several algorithmic paradigms for solving the multidimensional join problem, and we discuss their features and limitations. We propose a generalization of the Size Separation Spatial Join algorithm, named Multidimensional Spatial Join (MSJ), to solve the multidimensional join problem. We evaluate MSJ along with several other specific algorithms, comparing their performance for various dimensionalities on both real and synthetic multidimensional data sets. Our experimental results indicate that MSJ, which is based on space filling curves, consistently yields good performance across a wide range of dimensionalities.
{"title":"High dimensional similarity joins: algorithms and performance evaluation","authors":"Nick Koudas, K. Sevcik","doi":"10.1109/ICDE.1998.655809","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655809","url":null,"abstract":"Current data repositories include a variety of data types, including audio, images and time series. State of the art techniques for indexing such data and doing query processing rely on a transformation of data elements into points in a multidimensional feature space. Indexing and query processing then take place in the feature space. We study algorithms for finding relationships among points in multidimensional feature spaces, specifically algorithms for multidimensional joins. Like joins of conventional relations, correlations between multidimensional feature spaces can offer valuable information about the data sets involved. We present several algorithmic paradigms for solving the multidimensional join problem, and we discuss their features and limitations. We propose a generalization of the Size Separation Spatial Join algorithm, named Multidimensional Spatial Join (MSJ), to solve the multidimensional join problem. We evaluate MSJ along with several other specific algorithms, comparing their performance for various dimensionalities on both real and synthetic multidimensional data sets. Our experimental results indicate that MSJ, which is based on space filling curves, consistently yields good performance across a wide range of dimensionalities.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128593827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655779
Stefan Berchtold, Bernhard Ertl, D. Keim, H. Kriegel, T. Seidl
Similarity search in multimedia databases requires an efficient support of nearest neighbor search on a large set of high dimensional points as a basic operation for query processing. As recent theoretical results show, state of the art approaches to nearest neighbor search are not efficient in higher dimensions. In our new approach, we therefore precompute the result of any nearest neighbor search which corresponds to a computation of the voronoi cell of each data point. In a second step, we store the voronoi cells in an index structure efficient for high dimensional data spaces. As a result, nearest neighbor search corresponds to a simple point query on the index structure. Although our technique is based on a precomputation of the solution space, it is dynamic, i.e. it supports insertions of new data points. An extensive experimental evaluation of our technique demonstrates the high efficiency for uniformly distributed as well as real data. We obtained a significant reduction of the search time compared to nearest neighbor search in the X tree (up to a factor of 4).
{"title":"Fast nearest neighbor search in high-dimensional space","authors":"Stefan Berchtold, Bernhard Ertl, D. Keim, H. Kriegel, T. Seidl","doi":"10.1109/ICDE.1998.655779","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655779","url":null,"abstract":"Similarity search in multimedia databases requires an efficient support of nearest neighbor search on a large set of high dimensional points as a basic operation for query processing. As recent theoretical results show, state of the art approaches to nearest neighbor search are not efficient in higher dimensions. In our new approach, we therefore precompute the result of any nearest neighbor search which corresponds to a computation of the voronoi cell of each data point. In a second step, we store the voronoi cells in an index structure efficient for high dimensional data spaces. As a result, nearest neighbor search corresponds to a simple point query on the index structure. Although our technique is based on a precomputation of the solution space, it is dynamic, i.e. it supports insertions of new data points. An extensive experimental evaluation of our technique demonstrates the high efficiency for uniformly distributed as well as real data. We obtained a significant reduction of the search time compared to nearest neighbor search in the X tree (up to a factor of 4).","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129443392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655824
Peter Lang, W. Obermair, W. Kraus, T. Thalhammer
At the conceptual level, business rules are formulated from an external observation perspective according to the event-condition-action structure of rules in active database systems. Situation/activation diagrams homogeneously extend object/behavior diagrams to a graphical notation for the conceptual design of business objects and their associated business rules. Situation diagrams provide a high-level representation of logical events. Activation diagrams specify graphically which activities have to be performed upon some triggering event if an associated condition is satisfied. The developed editor supports both object/behavior diagrams and situation/activation diagrams. The editor performs syntactic consistency checks during the interactive design process. Moreover, by building the logical model in parallel with the diagrams, the editor guarantees that local semantic consistency checks can be performed incrementally, too. The editor clearly separates between schema data and pure visualization data describing the location of diagram elements. This separation facilitates the reuse of the generated data for further processing. Both schema data and visualization data are stored in the commercial object-oriented database system GemStone. Alternatively, those data may be stored in a file. The editor has been implemented using VisualWorks and MetaDoME, a framework for building graphical editors with VisualWorks.
{"title":"A graphical editor for the conceptual design of business rules","authors":"Peter Lang, W. Obermair, W. Kraus, T. Thalhammer","doi":"10.1109/ICDE.1998.655824","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655824","url":null,"abstract":"At the conceptual level, business rules are formulated from an external observation perspective according to the event-condition-action structure of rules in active database systems. Situation/activation diagrams homogeneously extend object/behavior diagrams to a graphical notation for the conceptual design of business objects and their associated business rules. Situation diagrams provide a high-level representation of logical events. Activation diagrams specify graphically which activities have to be performed upon some triggering event if an associated condition is satisfied. The developed editor supports both object/behavior diagrams and situation/activation diagrams. The editor performs syntactic consistency checks during the interactive design process. Moreover, by building the logical model in parallel with the diagrams, the editor guarantees that local semantic consistency checks can be performed incrementally, too. The editor clearly separates between schema data and pure visualization data describing the location of diagram elements. This separation facilitates the reuse of the generated data for further processing. Both schema data and visualization data are stored in the commercial object-oriented database system GemStone. Alternatively, those data may be stored in a file. The editor has been implemented using VisualWorks and MetaDoME, a framework for building graphical editors with VisualWorks.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121425187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655795
Xiaowei Xu, M. Ester, H. Kriegel, J. Sander
The problem of detecting clusters of points belonging to a spatial point process arises in many applications. In this paper, we introduce the new clustering algorithm DBCLASD (Distribution-Based Clustering of LArge Spatial Databases) to discover clusters of this type. The results of experiments demonstrate that DBCLASD, contrary to partitioning algorithms such as CLARANS (Clustering Large Applications based on RANdomized Search), discovers clusters of arbitrary shape. Furthermore, DBCLASD does not require any input parameters, in contrast to the clustering algorithm DBSCAN (Density-Based Spatial Clustering of Applications with Noise) requiring two input parameters, which may be difficult to provide for large databases. In terms of efficiency, DBCLASD is between CLARANS and DBSCAN, close to DBSCAN. Thus, the efficiency of DBCLASD on large spatial databases is very attractive when considering its nonparametric nature and its good quality for clusters of arbitrary shape.
在许多应用中都出现了检测属于空间点过程的点簇的问题。在本文中，我们引入了新的聚类算法DBCLASD (distributionbasedclustering of LArge Spatial Databases)来发现这类聚类。实验结果表明，与CLARANS(基于随机搜索的大型应用聚类)等划分算法相反，DBCLASD可以发现任意形状的聚类。此外，DBCLASD不需要任何输入参数，与需要两个输入参数的聚类算法DBSCAN (Density-Based Spatial clustering of Applications with Noise)不同，这对于大型数据库来说可能很难提供。在效率方面，DBCLASD介于CLARANS和DBSCAN之间，接近DBSCAN。因此，考虑到DBCLASD在大型空间数据库上的非参数性和对任意形状的簇的良好质量，它的效率非常有吸引力。
{"title":"A distribution-based clustering algorithm for mining in large spatial databases","authors":"Xiaowei Xu, M. Ester, H. Kriegel, J. Sander","doi":"10.1109/ICDE.1998.655795","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655795","url":null,"abstract":"The problem of detecting clusters of points belonging to a spatial point process arises in many applications. In this paper, we introduce the new clustering algorithm DBCLASD (Distribution-Based Clustering of LArge Spatial Databases) to discover clusters of this type. The results of experiments demonstrate that DBCLASD, contrary to partitioning algorithms such as CLARANS (Clustering Large Applications based on RANdomized Search), discovers clusters of arbitrary shape. Furthermore, DBCLASD does not require any input parameters, in contrast to the clustering algorithm DBSCAN (Density-Based Spatial Clustering of Applications with Noise) requiring two input parameters, which may be difficult to provide for large databases. In terms of efficiency, DBCLASD is between CLARANS and DBSCAN, close to DBSCAN. Thus, the efficiency of DBCLASD on large spatial databases is very attractive when considering its nonparametric nature and its good quality for clusters of arbitrary shape.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114831006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655805
DatabaseH. V. JagadishAT, Inderpal Singh MumickAT, Michael RabinovichAT
We present an efficient protocol for multi-version concurrency control in distributed databases. The protocol creates no more than three versions of any data item, while guaranteeing that: update transactions never interfere with read-only transactions; the version advancement mechanism is completely asynchronous with (both update and read-only) user transactions; and read-only transactions do not acquire locks and do not write control information into the data items being read. This is an improvement over existing multi-versioning schemes for distributed databases, which either require a potentially unlimited number of versions, or require coordination between version advancement and user transactions. Our protocol can be applied in a centralized system also, where the improvement over existing techniques is in reducing the number of versions from four to three. The proposed protocol is valuable in large applications that currently shut off access to the system while managing version advancement manually, but now have a need for automating this process and providing continuous access to the data.
{"title":"Asynchronous version advancement in a distributed three version database","authors":"DatabaseH. V. JagadishAT, Inderpal Singh MumickAT, Michael RabinovichAT","doi":"10.1109/ICDE.1998.655805","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655805","url":null,"abstract":"We present an efficient protocol for multi-version concurrency control in distributed databases. The protocol creates no more than three versions of any data item, while guaranteeing that: update transactions never interfere with read-only transactions; the version advancement mechanism is completely asynchronous with (both update and read-only) user transactions; and read-only transactions do not acquire locks and do not write control information into the data items being read. This is an improvement over existing multi-versioning schemes for distributed databases, which either require a potentially unlimited number of versions, or require coordination between version advancement and user transactions. Our protocol can be applied in a centralized system also, where the improvement over existing techniques is in reducing the number of versions from four to three. The proposed protocol is valuable in large applications that currently shut off access to the system while managing version advancement manually, but now have a need for automating this process and providing continuous access to the data.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131982596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655778
Byoung-Kee Yi, H. Jagadish, C. Faloutsos
Fast similarity searching in large time sequence databases has typically used Euclidean distance as a dissimilarity metric. However, for several applications, including matching of voice, audio and medical signals (e.g., electrocardiograms), one is required to permit local accelerations and decelerations in the rate of sequences, leading to a popular, field tested dissimilarity metric called the "time warping" distance. From the indexing viewpoint, this metric presents two major challenges: (a) it does not lead to any natural indexable "features", and (b) comparing two sequences requires time quadratic in the sequence length. To address each problem, we propose to use: (a) a modification of the so called "FastMap", to map sequences into points, with little compromise of "recall" (typically zero); and (b) a fast linear test, to help us discard quickly many of the false alarms that FastMap will typically introduce. Using both ideas in cascade, our proposed method achieved up to an order of magnitude speed-up over sequential scanning on both real and synthetic datasets.
{"title":"Efficient retrieval of similar time sequences under time warping","authors":"Byoung-Kee Yi, H. Jagadish, C. Faloutsos","doi":"10.1109/ICDE.1998.655778","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655778","url":null,"abstract":"Fast similarity searching in large time sequence databases has typically used Euclidean distance as a dissimilarity metric. However, for several applications, including matching of voice, audio and medical signals (e.g., electrocardiograms), one is required to permit local accelerations and decelerations in the rate of sequences, leading to a popular, field tested dissimilarity metric called the \"time warping\" distance. From the indexing viewpoint, this metric presents two major challenges: (a) it does not lead to any natural indexable \"features\", and (b) comparing two sequences requires time quadratic in the sequence length. To address each problem, we propose to use: (a) a modification of the so called \"FastMap\", to map sequences into points, with little compromise of \"recall\" (typically zero); and (b) a fast linear test, to help us discard quickly many of the false alarms that FastMap will typically introduce. Using both ideas in cascade, our proposed method achieved up to an order of magnitude speed-up over sequential scanning on both real and synthetic datasets.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132926911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-02-23DOI: 10.1109/ICDE.1998.655798
Hubert Naacke, G. Gardarin, A. Tomasic
Distributed systems require declarative access to diverse information sources. One approach to solving this heterogeneous distributed database problem is based on mediator architectures. In these architectures, mediators accept queries from users, process them with respect to wrappers, and return answers. Wrappers provide access to underlying sources. To efficiently process queries, the mediator must optimize the plan used for processing the query. In classical databases, cost-estimate based query optimization is effective. In a heterogeneous distributed databases, cost-estimate based query optimization is difficult to achieve because the underlying data sources do not export cost information. This paper describes a new method that permits the wrapper programmer to export cost estimates. For the wrapper programmer to describe all cost estimates may be impossible due to lack of information or burdensome due to the amount of information. We ease this responsibility of the wrapper programmer by leveraging the generic cost model of the mediator with specific cost estimates from the wrappers.
{"title":"Leveraging mediator cost models with heterogeneous data sources","authors":"Hubert Naacke, G. Gardarin, A. Tomasic","doi":"10.1109/ICDE.1998.655798","DOIUrl":"https://doi.org/10.1109/ICDE.1998.655798","url":null,"abstract":"Distributed systems require declarative access to diverse information sources. One approach to solving this heterogeneous distributed database problem is based on mediator architectures. In these architectures, mediators accept queries from users, process them with respect to wrappers, and return answers. Wrappers provide access to underlying sources. To efficiently process queries, the mediator must optimize the plan used for processing the query. In classical databases, cost-estimate based query optimization is effective. In a heterogeneous distributed databases, cost-estimate based query optimization is difficult to achieve because the underlying data sources do not export cost information. This paper describes a new method that permits the wrapper programmer to export cost estimates. For the wrapper programmer to describe all cost estimates may be impossible due to lack of information or burdensome due to the amount of information. We ease this responsibility of the wrapper programmer by leveraging the generic cost model of the mediator with specific cost estimates from the wrappers.","PeriodicalId":264926,"journal":{"name":"Proceedings 14th International Conference on Data Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132156522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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