Ontos, Ontos Reference Manual , Ontos, Inc., Burlington, MA, 1993.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....by people at Sun and the University of Glasgow. Implementation Approach PJama uses a modi ed Java interpreter to run Java programs. Since interpreted code runs much slower than compiled code, PJama s performance will be much worse compared to JPS. Moreover, PJama is an object caching system [Ont92, LAC 96] But as described in section 2.2.4, JPS uses the hybrid adaptive caching technique which has been shown to improve the performance of an OODB signi cantly. Persistence Model PJama supports persistence by reachability. It also supports garbage collection of persistent objects. The ....

Ontos Inc., Lowell, MA. Ontos Reference Manual, 1992.

....independent of a particular type model. This means that the model is general and can support interlanguage working. Proc. of the 12th Int. Conf. on the Entity Relationship Approach, Arlington, Texas, USA, December 1993 1 Many existing object oriented database systems such as O 2 [Deu91] ONTOS [Ont91] and ObjectStore [LLOW91] support collections of objects of differing behaviours, e.g. sets, bags (multisets) and sequences. However, the data models of such systems tend mainly to be type models and offer little in the way of constraints over collections of objects. It is therefore necessary to ....

ONTOS, Inc. ONTOS Reference Manual, 1991.

....provides significant opportunity for code reuse, extension and modification [57] Such databases usually provide environments where there is no impedance mismatch. Several commercial object oriented databases have appeared on the market. These commercial databases lack a mathematical foundation [25, 39, 67, 88, 110]. The lack of a mathematical foundation restricts the construction of effective design and optimization tools, inhibits usability, and adversely affects reliability. 1.3 Combining deductive and object oriented databases It seems natural to try to combine the features of deductive and ....

Ontos. ONTOS Reference Manual. Ontos, Inc., Billerica, Massachusetts, 1989.

....gap that the introduction mentioned in the area of multiuser OODBMS performance characteristics, we are currently developing a multi user OO7 OODBMS benchmark. There are five systems currently involved in this effort: E Exodus [CDF 86, RCS93] O2 [Deu91] Objectivity [Obj92] Ontos [Ont92] and Versant [Ver92] Our experience so far is that designing a multiuser benchmark is a much more difficult problem than designing a single user benchmark. This is partially due to the fact that the number of dimensions along which the workload can vary is greater in the multi user case, and ....

Ontos, Inc. Ontos reference manual. 1992.

....an application in the near future, and cold objects, which are not likely to be used soon. Bad clustering, i.e. a low fraction of hot objects per page, causes page caching to waste client cache space on cold objects that happen to reside in the same pages as hot objects. Object caching systems [Ont92, D 90, LAC 96, C , TG90, WD92, K 89] allow clients to cache hot objects without caching their containing disk pages and can thus achieve lower miss rates than page caching when clustering is bad. However, object caching has two problems: objects are variable sized units, which ....

Ontos. Inc. Ontos reference manual, 1992.

....prefetches many objects when clustering matches usage, and few objects when it doesn t. Thus we adapt minimizing the amount of cache space wasted and reducing network communication overheads. Others have developed caching schemes that are similar to ours in some respects. Some systems (e.g. Ont92, D 90] fetch and discard objects, but none has an adaptive prefetching algorithm. Ontos [Ont92] allows the user to specify at object creation time whether object based or page based fetching should be used for the new object. Our technique is better: it adapts over time, uses a wide range of ....

....adapt minimizing the amount of cache space wasted and reducing network communication overheads. Others have developed caching schemes that are similar to ours in some respects. Some systems (e.g. Ont92, D 90] fetch and discard objects, but none has an adaptive prefetching algorithm. Ontos [Ont92] allows the user to specify at object creation time whether object based or page based fetching should be used for the new object. Our technique is better: it adapts over time, uses a wide range of possible prefetch group sizes, and does not require programmer involvement. Some systems, such as ....

Ontos. Inc. Ontos reference manual, 1992.

....on the ODMG model) and EXTRA (Exodus) CDG 90] These systems must consider the issues related to query optimization and mutable set construction discussed in Section 3.1. We also looked at other systems that have pledged to adopt the OQL standard (e.g. Objectivity DB [Inc93] ONTOS [Ont93] and POET [Sof93] but have yet to receive documentation about how they intend to address these issues. 3 3 To the reviewers: We have sent a letter to each of these companies asking them how they plan to interpret the immutable sets produced by OQL queries and will update this section when we ....

Ontos. Ontos reference manual, 1993.

....difficulty of predicting the output of pseudo random functions and on finding extra sibling collision for the sibling intractable function family. 1 Introduction In recent years there has been considerable efforts in the research and development of objectoriented databases; ORION [19, 10] ONTOS [17], OBJECTSTORE [11] O 2 [5] Objectivity DB [15] and VERSANT [20] are examples of such efforts. The driving forces behind these efforts are the advantages offered by object oriented data models including the ability of object oriented model to represent the composite (or complex) structure of ....

Ontos. ONTOS Reference Manual. Ontologic, Inc., Billerica, Massachusetts, 1989.

....an application in the near future, and cold objects, which are not likely to be used soon. Bad clustering, i.e. a low fraction of hot objects per page, causes page caching to waste client cache space on cold objects that happen to reside in the same pages as hot objects. Object caching systems [Ont92, D 90, LAC 96, C 94b, KK90, WD92, KGBW90] allow clients to cache hot objects without caching their containing disk pages. Thus, object caching can achieve lower miss rates than page caching when clustering is bad. However, object caching has two problems: objects are variable sized units, which ....

Ontos, Inc., Lowell, MA. Ontos Reference Manual, 1992.

....an application in the near future, and cold objects, which are not likely to be used soon. Bad clustering, i.e. a low fraction of hot objects per page, causes page caching to waste client cache space on cold objects that happen to reside in the same pages as hot objects. Object caching systems [Ont92, D 90, LAC 96, C 94b, KK90, WD92, KGBW90] allow clients to cache hot objects without caching their containing disk pages. Thus, object caching can achieve lower miss rates than page caching when clustering is bad. However, object caching has two problems: objects are variable sized ....

Ontos, Inc., Lowell, MA. Ontos Reference Manual, 1992.

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Ontos, Ontos Reference Manual , Ontos, Inc., Burlington, MA, 1993.

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