Sam Spycher | Ecole Polytechnique Federale de Lausanne (original) (raw)
Papers by Sam Spycher
Database and Expert …, Jan 1, 2007
Prevailing concurrency control mechanisms for multidimensional index structures, such as the Gene... more Prevailing concurrency control mechanisms for multidimensional index structures, such as the Generalized Search Tree (GiST), are based on locking techniques. These approaches may cause significant overhead in settings where the indexed data is rarely updated and read access is highly concurrent. In this paper we present the Multiversion-GiST (MVGiST), which extends the GiST with Multiversion Concurrency Control. Beyond enabling lock-free read access, our approach provides readers a consistent view of the whole index structure ...
Web Services, 2005. …, Jan 1, 2005
In this paper we describe the implementation of multiversion concurrency control on the Generaliz... more In this paper we describe the implementation of multiversion concurrency control on the Generalized Search Tree (GiST), an index structure introduced by Hellerstein. For large-scale service directories, the need arises for a data storage system capable of handling substantial amounts of multidimensional data efficiently, as well as being able to support queries which are natural to the type of data stored in the directory. The GiST is an indexing structure that lends itself particularly well to this type of application. However, the solutions that have been proposed to address concurrency control on the GiST do not meet the requirements of large-scale service directories. The solution proposed here optimizes towards highly concurrent read accesses that are far more frequent than updates to the stored data. 1
Concurrency and …, Jan 1, 2009
Many read-intensive systems where fast access to data is more important than the rate at which da... more Many read-intensive systems where fast access to data is more important than the rate at which data can change make use of multidimensional index structures, like the generalized search tree (GiST). Although in these systems the indexed data are rarely updated and read access is highly concurrent, the existing concurrency control mechanisms for multidimensional index structures are based on locking techniques, which cause significant overhead. In this article we present the multiversion-GiST (MVGiST), an inmemory mechanism that extends the GiST with multiversion concurrency control. The MVGiST enables lock-free read access and ensures a consistent view of the index structure throughout a reader's series of queries, by creating lightweight, read-only versions of the GiST that share unchanging nodes among themselves. An example of a system with high read to write ratio, where providing wait-free queries is of utmost importance, is a large-scale directory that indexes web services according to their input and output parameters. A performance evaluation shows that for low update rates, the MVGiST significantly improves scalability w.r.t. the number of concurrent read accesses when compared with a traditional, locking-based concurrency control mechanism. We propose a technique to control memory consumption and confirm through our evaluation that the MVGiST efficiently manages memory.
Web Services, 2007. …, Jan 1, 2007
Abstract Web service directories are shared resources that have to accommodate a high number of c... more Abstract Web service directories are shared resources that have to accommodate a high number of concurrent read requests, whereas updates are relatively infrequent. To allow for the automatic composition of complex web services based on those contained in a directory, read requests may involve a series of queries which require a consistent view of the data. We have developed an efficient web service directory that is based on the Multiversion Generalised Search Tree (MVGiST), an integration of a multidimensional index structure ...
Database and Expert …, Jan 1, 2007
Prevailing concurrency control mechanisms for multidimensional index structures, such as the Gene... more Prevailing concurrency control mechanisms for multidimensional index structures, such as the Generalized Search Tree (GiST), are based on locking techniques. These approaches may cause significant overhead in settings where the indexed data is rarely updated and read access is highly concurrent. In this paper we present the Multiversion-GiST (MVGiST), which extends the GiST with Multiversion Concurrency Control. Beyond enabling lock-free read access, our approach provides readers a consistent view of the whole index structure ...
Web Services, 2005. …, Jan 1, 2005
In this paper we describe the implementation of multiversion concurrency control on the Generaliz... more In this paper we describe the implementation of multiversion concurrency control on the Generalized Search Tree (GiST), an index structure introduced by Hellerstein. For large-scale service directories, the need arises for a data storage system capable of handling substantial amounts of multidimensional data efficiently, as well as being able to support queries which are natural to the type of data stored in the directory. The GiST is an indexing structure that lends itself particularly well to this type of application. However, the solutions that have been proposed to address concurrency control on the GiST do not meet the requirements of large-scale service directories. The solution proposed here optimizes towards highly concurrent read accesses that are far more frequent than updates to the stored data. 1
Concurrency and …, Jan 1, 2009
Many read-intensive systems where fast access to data is more important than the rate at which da... more Many read-intensive systems where fast access to data is more important than the rate at which data can change make use of multidimensional index structures, like the generalized search tree (GiST). Although in these systems the indexed data are rarely updated and read access is highly concurrent, the existing concurrency control mechanisms for multidimensional index structures are based on locking techniques, which cause significant overhead. In this article we present the multiversion-GiST (MVGiST), an inmemory mechanism that extends the GiST with multiversion concurrency control. The MVGiST enables lock-free read access and ensures a consistent view of the index structure throughout a reader's series of queries, by creating lightweight, read-only versions of the GiST that share unchanging nodes among themselves. An example of a system with high read to write ratio, where providing wait-free queries is of utmost importance, is a large-scale directory that indexes web services according to their input and output parameters. A performance evaluation shows that for low update rates, the MVGiST significantly improves scalability w.r.t. the number of concurrent read accesses when compared with a traditional, locking-based concurrency control mechanism. We propose a technique to control memory consumption and confirm through our evaluation that the MVGiST efficiently manages memory.
Web Services, 2007. …, Jan 1, 2007
Abstract Web service directories are shared resources that have to accommodate a high number of c... more Abstract Web service directories are shared resources that have to accommodate a high number of concurrent read requests, whereas updates are relatively infrequent. To allow for the automatic composition of complex web services based on those contained in a directory, read requests may involve a series of queries which require a consistent view of the data. We have developed an efficient web service directory that is based on the Multiversion Generalised Search Tree (MVGiST), an integration of a multidimensional index structure ...