V.J.Tsotras, N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, 20(3), 1995.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....extremely space efficient comprehensive versioning. In addition to the significant file system work in versioning, there has been quite a bit of work done in the database community for keeping versions of data through time. Most of this work has been done in the form of temporal data structures [2, 23, 24, 44, 45]. Our directory structure borrows from these techniques. The log structured data layout was developed for writeonce media [33] and later extended to provide write performance benefits for read write disk technology [36] Since its inception, LFS has been evaluated [3, 28, 35, 38] and used [1, 7, ....

V. J. Tsotras and N. Kangelaris. The snapshot index - an I/O-optimal access method for timeslice queries. Information Systems, 20(3):237--260, May 1995.

....CVFS to provide efficient comprehensive versioning. In addition to the significant file system work in versioning, there has been quite a bit of work done in the database community for keeping versions of data through time. Most of this work has been done in the form of temporal data structures [2, 22, 23, 44, 45]. Our directory structure borrows from these techniques. The log structured data layout was developed for write once media [33] and later extended to provide write performance benefits for read write disk technology [36] Since its inception, LFS has been evaluated [3, 27, 35, 38] and used [1, ....

V. J. Tsotras and N. Kangelaris. The snapshot index - an I/O-optimal access method for timeslice queries. Information Systems, 20(3):237-- 260, May 1995.

....Temporal index structures with this scope include the TSB tree [LS89, LS90] the MVBT [Bec96] the Two Level Time Index [EWK93] the R tree [Gut84] and the Segment Rtree [Ko193] a variant of the R tree specifically suited for temporal databases. Temporal index structures like the Snapshot Index [TK95], the Time Index [EWK93, EKW91] and the TP Index [SOL94] aim only at supporting specific query types effciently. Comparing them with other index structures is only meaningful based on a specific kind of application. Among the index structures with a general aim, the TSB tree has demonstrated very ....

V. J. Tsotras, N. Kangelaris, The Snapshot Index: An I/O-Optimal Access Method for Timeslice Queries, Information Systems, Vol. 20, No. 3, 1995

.... The main focus of research in temporal databases has been the modeling and representation of temporal data [Tan93] SAA 94] Smi92] Concerns about the performance of temporal operations were less signicant, although there were some developments in the domain of temporal access methods [GS93] TK95] Constraint databases are a new emerging class of databases where the basic idea is to replace the notion of tuple in a relational database by that of generalized tuple, i.e. a conjunction of constraints. By choosing classes of constraints, one can represent potentially innite sets of points ....

Vassilis J. Tsotras and Nickolas Kangelaris. The snapshot index: An I/O-optimal access method for timeslice queries. Information Systems, 20(3):237-260, 1995.

.... Index [SOL94] and Interval B tree [AT95] ffl Those considering valid time but also assuming that input data is monotonically growing (append only) Monotonic B tree [EJK92] and Append Only Tree [GS93] ffl Those indexing transaction time only: Time Split B tree [LS93] and Snapshot Index [TK93] ffl Those based on Spatial oriented data such as the R tree [Gut84] and its derivatives) ffl And bitemporal structures: Incremental Valid Time Trees [NDE95] and derivatives) Sharing Trees [NE95] and the Bitemporal Interval Tree and Bitemporal R Tree [KTF95] ....

V.J. Tsotras and N. Kangelaris. The snapshot index, an I/O optimal access method for timeslice queries. Technical Report CATT-TR-93-68, Polytechnic University, December 1993.

....thus we can state that (V k s Gamma V l s ) 0. Substituting this into Equation 2 we obtain that (V k e Gamma V l e ) 0 which contradicts the initial assumption (V k 6= V l . Hence, M (V k ) M (V l ) V k = V l . Q.E.D. For example, assuming ff = 2, the ranges [1,4] [9,13] and [78, 98] would be respectively mapped into 104, 913 and 7898, and these would be the indexed values in the MAP21 indexing structure. It is straightforward to apply an inverse mapping function, thus finding the original range, namely: V k = F Gamma1 s (F (V k ) F Gamma1 e (F (V ....

....valid time has the very same characteristics as transaction time, i.e. only monotonically increasing values are input as valid times. Some of the structures reviewed would not require such assumption, such as the Time Index [3] or the R tree [6] while others would (AP tree [5] Snapshot Index [13], TSB tree [9] In the case of MAP21, such assumption is indeed beneficial (but not required, as it will imply that not only the indexing structure itself is clustered (which is indeed the case) but also the data records. A review of the approaches and the structures used can be found elsewhere ....

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V.J. Tsotras and N. Kangelaris. The snapshot index, an I/O optimal access method for timeslice queries. Information Systems, 3(20):237--260, 1995.

....is mapped into a B tree. This approach is similar to the one we propose, but there are some fundamental differences. We discuss these differences in more detail in Section 5, after presenting our approach. The Monotonic B tree [EWK93] the Append Only Tree [GS93] and the Snapshot Index [TK95] also aim at indexing valid time ranges. However they require the input to be given with the valid start time in increasingly monotonic order, which is a transaction time characteristic. This prevents these approaches from handling either predictive or retroactive updates. The Time Split B tree ....

V.J. Tsotras and N. Kangelaris. The snapshot index, an I/O optimal access method for timeslice queries. Information Systems, 3(20):237--260, 1995.

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V.J.Tsotras, N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, 20(3), 1995.

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V.J. Tsotras and N. Kangelaris, \The Snapshot Index: An I/O-Optimal Access Method for Timeslice Queries", Information Systems 20(3), 1995.

....structural change is a node overflow; the latter is a weak version underflow [5] Node overflow and weak version underflow need special handling: a split is performed on the target leaf node. This is reminiscent of the time split operation reported in [27] and the page copying concept proposed in [46]. Splitting a node x at frame f is performed by copying to a new node y the records alive in node x at f . Node x is considered dead after frame f . We can assume that the deletion frame field of all x s alive records is changed to f even though this is not needed in practice) To avoid having a ....

V.J.Tsotras, N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, 20(3), 1995.

....structural change is a node overflow; the latter is a weak version underflow [4] Node overflow and weak version underflow need special handling: a split is performed on the target leaf node. This is reminiscent of the time split operation reported in [20] and the page copying concept proposed in [37]. Splitting a node x at time t is performed by copying to a new node y the records alive in node x at t. Node x is considered dead after time t. To avoid having a structural change on node y soon, when a new node is created the number of alive records must be in the range D e and B e (where e is ....

V. Tsotras and N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, Vol. 20, No. 3, pages 237--260, 1995.

....as a result of the deletion. The former structural change is a page over ow; the latter is a weak version under ow [1] Page over ow and weak version under ow need special handling: a split is performed on the target leaf page. This is similar to the time split of [7] or the page copying of [11]. The split on a page x at frame f , is performed by copying to a new page y the records alive in page x at f . Page x is considered dead after frame f . We can assume that the deletion frame eld of all x s alive records is changed to f even though this is not needed in practice) Then the ....

V.J.Tsotras, N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, 20(3), 1995.

....the actual document data from the edit script, and (ii) uses the usefulness based clustering scheme (UBCC) for page management. Because of (i) the script is rather small and can be easily accessed. The usefulness based clustering is similar to a technique used in transaction time databases [17, 25, 2] to cluster temporal data and is outlined below. 2.1 Usefulness based clustering Consider the actual document objects and their organization in disk pages. For simplicity, assume the only changes between document versions are object additions and deletions. As objects are added in the document, ....

....is initiated as (V start ; now) and later updated at V end . Identifying the data pages that were useful at V i is then equivalent to nding which pages have intervals that contain V i . This problem has been solved in temporal databases [19] with an access method called the Snapshot Index [25, 21]. If there were k useful pages at V i , they are located with O(k) e ort. These useful pages contain all document elements at V i , however, the elements may be stored out of their logical document order. Therefore, the second step is to sort the elements by their SPaR number. It should be noted ....

V.J. Tsotras and N. Kangelaris, \The Snapshot Index: An I/O-Optimal Access Method for Timeslice Queries", Information Systems 20(3), pp. 237-260, 1995.

....structural change is a node over ow; the latter is a weak version under ow [5] Node over ow and weak version under ow need special handling: a split is performed on the target leaf node. This is reminiscent of the time split operation reported in [27] and the page copying concept proposed in [46]. Splitting a node x at frame f is performed by copying to a new node y the records alive in node x at f . Node x is considered dead after frame f . We can assume that the deletion frame eld of all x s alive records is changed to f even though this is not needed in practice) To avoid having a ....

V.J.Tsotras, N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, 20(3), 1995.

....as a result of the deletion. The former structural change is a page overflow; the latter is a weak version underflow [1] Page overflow and weak version underflow need special handling: a split is performed on the target leaf page. This is similar to the time split of [7] or the page copying of [11]. The split on a page x at frame f , is performed by copying to a new page y the records alive in page x at f . Page x is considered dead after frame f . We can assume that the deletion frame field of all x s alive records is changed to f even though this is not needed in practice) Then the ....

V.J.Tsotras, N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, 20(3), 1995.

....The former structural change is a node overflow; the latter is a weak version underflow [5] Node overflow and weak version underflow need special handling: a split is performed on the target leaf node. This is reminiscent of the time split proposal [26] and the page copying concept proposed in [43]. The split on a node x at frame f , is performed by copying to a new node y the records alive in node x at f . Node x is considered dead after frame f . We can assume that the deletion frame field of all x s alive records is changed to f even though this is not needed in practice) Then the ....

V.J.Tsotras, N. Kangelaris. The Snapshot Index, an I/O-Optimal Access Method for Timeslice Queries. Information Systems, 20(3), 1995.

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