A Data warehouse within a Federated database architecture

Research in heterogeneous databases [Sheth & Larson 90] have provided methods to integrate disparate databases into a single unifying architecture -the federated database model. But they are limited in as much as: 1) The federated schema is non-materialized, which means that queries will have to be evaluated in the individual databases, resulting in slower response time, and 2) Data from external sources are not integrated within the federated schema. We propose to extend the federated architecture to include a data warehouse [Inmon 94, Kimball 96] modeled as a materialized view [Hanson 87] of the underlying federated schema. In addition, we employ view maintenance techniques to maintain the data warehouse against changes in the underlying operational sources. We adopt a deferredview maintenance [Colby et al 96] approach, rather than immediateapproach adopted by Stanford WHIPS project [Hammer et al 95]. This approach is preferred, because a great deal of decision-making may not require current data, but for those that require them, the model provides a mechanism to obtain them without adding too much overhead. For example, a data warehouse at a central office of a large chain of stores would like to have access to current inventory levels at individual stores, before deciding on a promotion. Similarly, access to both historical and current data of stock prices help an investment company to re-create point-in-time snapshots to help predict movements in stock prices. This approach provides the following advantages: •A unified architecture that ties the data warehouse to multiple heterogeneous databases. •Provides a method of maintaining the data warehouse as an integrated materialized view of the underlying data sources. •Provides flexible access to current data residing in the data sources. •Ease of maintenance against any change to the schema in the data source or warehouse

Asian Elephant and Bannerghatta National Park in Eastern Ghats, Southern India

The park lies between 120 34’and 120 50’N latitudes and between 770 31’and 770 38’E longitudes (Rajeev 2002). The park area has been divided into three wildlife ranges, Viz. Bannerghatta, Harohalli and Anekal Wildlife Range for the convenience of administration. It is highly irregular in shape and measures a maximum of 26 km in length from North to South and varies between 0.3 and 5 km in widt

Asian Elephant and Bannerghatta National Park in Eastern Ghats, Southern India

The park lies between 120 34’and 120 50’N latitudes and between 770 31’and 770 38’E longitudes (Rajeev 2002). The park area has been divided into three wildlife ranges, Viz. Bannerghatta, Harohalli and Anekal Wildlife Range for the convenience of administration. It is highly irregular in shape and measures a maximum of 26 km in length from North to South and varies between 0.3 and 5 km in widt

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

MAINTENANCE ISSUES IN DATA WAREHOUSING

Master'sMASTER OF SCIENCE (MANAGEMENT

Automated timetabling using an object-oriented scheduler

10.1016/0957-4174(95)00050-XExpert Systems with Applications102243-256ESAP