Bitmap index Database index

-


a bitmap index special kind of indexing stores bulk of data bit arrays (bitmaps) , answers queries performing bitwise logical operations on these bitmaps. commonly used indexes, such b+ trees, efficient if values index not repeat or repeat small number of times. in contrast, bitmap index designed cases values of variable repeat frequently. example, sex field in customer database contains @ 3 distinct values: male, female or unknown (not recorded). such variables, bitmap index can have significant performance advantage on commonly used trees.







Comments

Post a Comment

Popular posts from this blog

Precise Pb.E2.80.93Pb dating of meteorites Lead–lead dating

-
pb–pb isochrons oldest known material in solar system. chondrules , calcium–aluminium-rich inclusions (cais) spherical particles make chondritic meteorites , believed oldest objects in solar system. hence precise dating of these objects important constrain evolution of solar system , age of earth. u–pb dating method can yield precise ages solar-system objects due optimal half-life of u. however, absence of zircon or other uranium-rich minerals in chondrites, , presence of initial non-radiogenic pb (common pb), rules out direct use of u-pb concordia method. therefore, precise dating method these meteorites pb–pb method, allows correction common pb. when abundance of pb relatively low, isotope has larger measurement errors other pb isotopes, leading strong correlation of errors between measured ratios. makes difficult determine analytical uncertainty on age. avoid problem, researchers developed ‘alternative pb–pb isochron diagram’ (see figure) reduced error correlation between measured r...
Read more

Administrative and offices Campus of the University of Montana

-
1 administrative , offices 1.1 brantly hall 1.2 corbin hall 1.3 curry health center 1.4 emma b. lommasson center 1.5 university (main) hall 1.6 university center administrative , offices brantly hall (the university of montana historic district contributing property) formerly north hall built 1923 abv. bran constructed in 1922 following 1918 carsley-gilbert campus master plan, women’s residence intended part of 2 u-shaped clusters of men’s , women’s dormitories. identical contemporary counterpart, elrod hall, , corbin hall 3 buildings of 2 “u”s erected before plan abandoned in 1930s. renowned helena architects j. g. link , c. s. haire designed handsome renaissance revival style facility striking red-brown brick façade , simple cream-colored terra cotta ornamentation. renamed brantly hall, building functioned women’s residence until 1987. had been renamed in honor of lois (reat) brantly, had been social director of hall on 16 years. mrs. brantly had been considered a, mother away home....
Read more

Understanding the dangers Tornado preparedness

-
a tornado no obvious funnel upper clouds, although rotating dust cloud indicates strong winds @ surface. a tornado operates rotating, funnel-shaped cloud extends downward thunderstorm, ground, swirling winds have reached 300 miles per hour (480 km/h). wind speed might difficult imagine: traveling length of u.s. football field within 1 second (over 130 meters or 430 feet per second). damage paths have been in excess of one-mile wide (1.6 km) , 50 miles long (80 km). not tornadoes seen. tornado funnel can transparent until reaching area loose dirt , debris. also, tornadoes have been seen against sunlit areas, rain or nearby low-hanging clouds has obscured other tornadoes. occasionally, tornadoes have developed suddenly, rapidly, little, if any, advance warning possible. before tornado strikes area, wind has been known die down , air become still. cloud of debris has marked bottom of tornado when funnel not visible. tornadoes typically occur along trailing edge of thundersto...
Read more