Pub Date : 1995-03-06DOI: 10.1109/ICDE.1995.380398
Walid G. Aref, Daniel Barbará, Stephen Johnson, S. Mehrotra
Emerging multimedia applications require database systems to provide support for new types of objects and to process queries that may have no parallel in traditional database applications. One such important class of queries are the proximity queries that aims to retrieve objects in the database that are related by a distance metric in a way that is specified by the query. The importance of proximity queries has earlier been realized in developing constructs for visual languages. In this paper, we present algorithms for answering a class of proximity queries-fixed-radius nearest-neighbor queries over point object. Processing proximity queries using existing query processing techniques results in high CPU and I/O costs. We develop new algorithms to answer proximity queries over objects that lie in the one-dimensional space (e.g., words in a document). The algorithms exploit query semantics to reduce the CPU and I/O costs, and hence improve performance. We also show how our algorithms can be generalized to handle d-dimensional objects.<>
{"title":"Efficient processing of proximity queries for large databases","authors":"Walid G. Aref, Daniel Barbará, Stephen Johnson, S. Mehrotra","doi":"10.1109/ICDE.1995.380398","DOIUrl":"https://doi.org/10.1109/ICDE.1995.380398","url":null,"abstract":"Emerging multimedia applications require database systems to provide support for new types of objects and to process queries that may have no parallel in traditional database applications. One such important class of queries are the proximity queries that aims to retrieve objects in the database that are related by a distance metric in a way that is specified by the query. The importance of proximity queries has earlier been realized in developing constructs for visual languages. In this paper, we present algorithms for answering a class of proximity queries-fixed-radius nearest-neighbor queries over point object. Processing proximity queries using existing query processing techniques results in high CPU and I/O costs. We develop new algorithms to answer proximity queries over objects that lie in the one-dimensional space (e.g., words in a document). The algorithms exploit query semantics to reduce the CPU and I/O costs, and hence improve performance. We also show how our algorithms can be generalized to handle d-dimensional objects.<<ETX>>","PeriodicalId":184415,"journal":{"name":"Proceedings of the Eleventh International Conference on Data Engineering","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126978839","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 : 1995-03-06DOI: 10.1109/ICDE.1995.380380
A. Biliris, E. Panagos
The paper describes the client-server software architecture of the EOS storage manager and the concurrency control and recovery mechanisms it employs. Unlike most client-server storage systems that use the standard two-phase locking protocol, EOS offers a semi-optimistic locking scheme based on a multigranularity two-version two-phase locking protocol. Under this scheme, many readers are allowed to access a data item while it is being updated by a single writer. For recovery, EOS maintains a write-ahead redo-only log because of the potential benefits it offers in a client-server environment. First, there are no undo records, as log records of aborted transactions are never inserted in the log; this minimizes the I/O and network transfer costs associated with logging during normal transaction execution. Secondly, it reduces the space required for the log. Thirdly, it facilitates fast recovery from system crashes because only one forward scan of the log is required for installing the updates performed by transactions that committed prior to the crash. Performance results of the EOS recovery subsystem are also presented.<>
{"title":"Transactions in the client-server EOS object store","authors":"A. Biliris, E. Panagos","doi":"10.1109/ICDE.1995.380380","DOIUrl":"https://doi.org/10.1109/ICDE.1995.380380","url":null,"abstract":"The paper describes the client-server software architecture of the EOS storage manager and the concurrency control and recovery mechanisms it employs. Unlike most client-server storage systems that use the standard two-phase locking protocol, EOS offers a semi-optimistic locking scheme based on a multigranularity two-version two-phase locking protocol. Under this scheme, many readers are allowed to access a data item while it is being updated by a single writer. For recovery, EOS maintains a write-ahead redo-only log because of the potential benefits it offers in a client-server environment. First, there are no undo records, as log records of aborted transactions are never inserted in the log; this minimizes the I/O and network transfer costs associated with logging during normal transaction execution. Secondly, it reduces the space required for the log. Thirdly, it facilitates fast recovery from system crashes because only one forward scan of the log is required for installing the updates performed by transactions that committed prior to the crash. Performance results of the EOS recovery subsystem are also presented.<<ETX>>","PeriodicalId":184415,"journal":{"name":"Proceedings of the Eleventh International Conference on Data Engineering","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126173913","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 : 1995-03-06DOI: 10.1109/ICDE.1995.380358
I. Chen, V. Markowitz
We examine the main requirements for modeling scientific experiments and propose constructs that fulfil these requirements. We show that existing object-oriented and semantic data models do not provide such constructs. Experiment (protocol) and object constructs can be combined in order to provide seamless object and experiment modeling. We present an example of combining protocol and object constructs into a unified framework, the Object-Protocol Model (OPM), and briefly describe the implementation of an OPM interface on top of commercial relational database management systems (DBMSs).<>
{"title":"Modeling scientific experiments with an object data model","authors":"I. Chen, V. Markowitz","doi":"10.1109/ICDE.1995.380358","DOIUrl":"https://doi.org/10.1109/ICDE.1995.380358","url":null,"abstract":"We examine the main requirements for modeling scientific experiments and propose constructs that fulfil these requirements. We show that existing object-oriented and semantic data models do not provide such constructs. Experiment (protocol) and object constructs can be combined in order to provide seamless object and experiment modeling. We present an example of combining protocol and object constructs into a unified framework, the Object-Protocol Model (OPM), and briefly describe the implementation of an OPM interface on top of commercial relational database management systems (DBMSs).<<ETX>>","PeriodicalId":184415,"journal":{"name":"Proceedings of the Eleventh International Conference on Data Engineering","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125824497","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 : 1995-03-06DOI: 10.1109/ICDE.1995.380397
R. Peters, M. Tamer Özsu
The schema of a system consists of the constructs that model its entities. Schema evolution is the timely change and management of the schema. Dynamic schema evolution is the management of schema changes while the system is in operation. We propose a sound and complete axiomatic model for dynamic schema evolution in object-base management systems (OBMSs) that support subtyping and property inheritance. The model is formal, which distinguishes it from the traditional approach of informally defining a number of invariants and rules to enforce them. By reducing systems to the axiomatic model, their functionality with respect to dynamic schema evolution can be compared within a common framework.<>
{"title":"Axiomatization of dynamic schema evolution in object bases","authors":"R. Peters, M. Tamer Özsu","doi":"10.1109/ICDE.1995.380397","DOIUrl":"https://doi.org/10.1109/ICDE.1995.380397","url":null,"abstract":"The schema of a system consists of the constructs that model its entities. Schema evolution is the timely change and management of the schema. Dynamic schema evolution is the management of schema changes while the system is in operation. We propose a sound and complete axiomatic model for dynamic schema evolution in object-base management systems (OBMSs) that support subtyping and property inheritance. The model is formal, which distinguishes it from the traditional approach of informally defining a number of invariants and rules to enforce them. By reducing systems to the axiomatic model, their functionality with respect to dynamic schema evolution can be compared within a common framework.<<ETX>>","PeriodicalId":184415,"journal":{"name":"Proceedings of the Eleventh International Conference on Data Engineering","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131083823","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 : 1995-03-06DOI: 10.1109/ICDE.1995.380386
Y. Papakonstantinou, H. Garcia-Molina, J. Widom
We address the problem of providing integrated access to diverse and dynamic information sources. We explain how this problem differs from the traditional database integration problem and we focus on one aspect of the information integration problem, namely information exchange. We define an object-based information exchange model and a corresponding query language that we believe are well suited for integration of diverse information sources. We describe how, the model and language have been used to integrate heterogeneous bibliographic information sources. We also describe two general-purpose libraries we have implemented for object exchange between clients and servers.<>
{"title":"Object exchange across heterogeneous information sources","authors":"Y. Papakonstantinou, H. Garcia-Molina, J. Widom","doi":"10.1109/ICDE.1995.380386","DOIUrl":"https://doi.org/10.1109/ICDE.1995.380386","url":null,"abstract":"We address the problem of providing integrated access to diverse and dynamic information sources. We explain how this problem differs from the traditional database integration problem and we focus on one aspect of the information integration problem, namely information exchange. We define an object-based information exchange model and a corresponding query language that we believe are well suited for integration of diverse information sources. We describe how, the model and language have been used to integrate heterogeneous bibliographic information sources. We also describe two general-purpose libraries we have implemented for object exchange between clients and servers.<<ETX>>","PeriodicalId":184415,"journal":{"name":"Proceedings of the Eleventh International Conference on Data Engineering","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132533643","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 : 1995-03-06DOI: 10.1109/ICDE.1995.380378
C. Mohan
We discuss several disk read-write optimizations that are implemented in different transaction systems and disk hardware to improve performance. These include: (1) when multiple sectors are written to disk, the sectors may be written out of sequence (SCSI disk interfaces do this). (2) Avoiding initializing pages on disk when a file is extended. (3) Not accessing individual pages during a mass delete operation (e.g., dropping an index from a file which contains multiple indexes). (4) Permitting a previously deallocated page to be reallocated without the need to read the deallocated version of the page from disk during its reallocation. (5) Purging of file pages from the buffer pool during a file erase operation (e.g., a table drop). (6) Avoiding logging for bulk operations like index create. We consider a system which implements the above optimizations and in which a page consists of multiple disk sectors and recovery is based on write-ahead logging using a log sequence number on every page. For such a system, we present a simple method for guaranteeing the detection of the partial disk write of a page. Detecting partial writes is very important not only to ensure data integrity from the users' viewpoint but also to make the transaction system software work correctly. Once a partial write is detected, it is easy to recover such a page using media recovery techniques. Our method imposes minimal CPU and space overheads. It has been implemented in DB2/6000 and ADSM.<>
{"title":"Disk read-write optimizations and data integrity in transaction systems using write-ahead logging","authors":"C. Mohan","doi":"10.1109/ICDE.1995.380378","DOIUrl":"https://doi.org/10.1109/ICDE.1995.380378","url":null,"abstract":"We discuss several disk read-write optimizations that are implemented in different transaction systems and disk hardware to improve performance. These include: (1) when multiple sectors are written to disk, the sectors may be written out of sequence (SCSI disk interfaces do this). (2) Avoiding initializing pages on disk when a file is extended. (3) Not accessing individual pages during a mass delete operation (e.g., dropping an index from a file which contains multiple indexes). (4) Permitting a previously deallocated page to be reallocated without the need to read the deallocated version of the page from disk during its reallocation. (5) Purging of file pages from the buffer pool during a file erase operation (e.g., a table drop). (6) Avoiding logging for bulk operations like index create. We consider a system which implements the above optimizations and in which a page consists of multiple disk sectors and recovery is based on write-ahead logging using a log sequence number on every page. For such a system, we present a simple method for guaranteeing the detection of the partial disk write of a page. Detecting partial writes is very important not only to ensure data integrity from the users' viewpoint but also to make the transaction system software work correctly. Once a partial write is detected, it is easy to recover such a page using media recovery techniques. Our method imposes minimal CPU and space overheads. It has been implemented in DB2/6000 and ADSM.<<ETX>>","PeriodicalId":184415,"journal":{"name":"Proceedings of the Eleventh International Conference on Data Engineering","volume":"56 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126074524","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 : 1995-03-06DOI: 10.1109/ICDE.1995.380359
C. Kalus, P. Dadam
The model of flexible relations supports heterogeneous sets of tuples in a strongly typed way. The elegance of the standard relational model is presented by using a single, generic scheme constructor. In each model supporting structural variants the shape of some part of a heterogeneous scheme may be determined by the contents of some other part of the scheme. We formalize this relationship by a certain kind of integrity constraint we have called "attribute dependency" (AD). We motivate how ADs can be used, besides their application in type and integrity checking, to incorporate record subtyping into our extended relational model. Moreover, we show that ADs yield a stronger assertion than the traditional record subtyping rub as they consider interdependencies among refinements. We discuss how ADs are related to query processing and how they may help to identify redundant operations.<>
{"title":"Record subtyping in flexible relations by means of attribute dependencies","authors":"C. Kalus, P. Dadam","doi":"10.1109/ICDE.1995.380359","DOIUrl":"https://doi.org/10.1109/ICDE.1995.380359","url":null,"abstract":"The model of flexible relations supports heterogeneous sets of tuples in a strongly typed way. The elegance of the standard relational model is presented by using a single, generic scheme constructor. In each model supporting structural variants the shape of some part of a heterogeneous scheme may be determined by the contents of some other part of the scheme. We formalize this relationship by a certain kind of integrity constraint we have called \"attribute dependency\" (AD). We motivate how ADs can be used, besides their application in type and integrity checking, to incorporate record subtyping into our extended relational model. Moreover, we show that ADs yield a stronger assertion than the traditional record subtyping rub as they consider interdependencies among refinements. We discuss how ADs are related to query processing and how they may help to identify redundant operations.<<ETX>>","PeriodicalId":184415,"journal":{"name":"Proceedings of the Eleventh International Conference on Data Engineering","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126096442","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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