Description:
Discussing advances in database technology.
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Imeliä säkeitä
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Transmutaatiotekniikasta. *Maassamme ydinalalla on tuskin mitään niin tarkoin TABU:na pirettyä systeemiä, kuin mahdollisuus neutraloida edes osin maailman vaarallisimpia ihmiskunnan ydinjätemoskiaan ydinvoimalasaasteista. Päivän selvää on, että tämä olisi mahdollista, koska sotilassektorilla systeemiä on pyöritetty... more »
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a union is always a join!
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Criticisms, please (preferably ones based on some formal logic or other). It is inescapable that every relation is a join (eg., Heath's theorem). So every relvar points to a join. If we can't 'delete' through a join, we can't delete from any relvar (my father, who thought a disk buffer was a polishing material could have concluded this - also, I surmise, we... more »
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Jakohihna Mazda 323 1,5 familia BA 1996
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Ydinalan disinformaatiosyyd ss huomaa aiheen synnytt m n panikin. Totuus ei heit miellyt . Mutta koska haluan varmistaa aina KAIKEN todenper isyyden selvitin my s ne "mystiset" tilanteet, joissa oli mehil isi viel tallessa. Nimitt in sellaisia erikoistapauksia yh maassamme ON! Jopa... more »
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DBMS recommendation?
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Hi, We are currently thinking of replacing our existing database system which is no longer supported. The data corpus encompasses 4 million records each of which having about 30 fields. Half a million records would have a full text in PDF format which we also put as a text field (by a self-made PDF extraction script).... more »
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EISWT-09 call for papers
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EISWT-09 call for papers The 2009 International Conference on Enterprise Information Systems and Web Technologies (EISWT-09) (website: [link] ) will be held during July 13-16 2009 in Orlando, FL, USA. We invite draft paper submissions. The conference will take place at the same... more »
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Mike Carey on data modeling (and other videos)
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"Data Services Modeling: Data Modeling for the SOA Age", a presentation by Dr. Michael Carey, is now available for listening (MP3 podcast) or viewing (web video for desktop, mobile or cell phone playback). Mike Carey is the Donald Bren Professor of Computer and Information Sciences at the University of California, Irvine. He's an ACM Fellow,... more »
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A different definition of MINUS, part 4
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Parts one, two and three have various mis-steps and confusions. Let me start again emphasizing what I think was McGoveran's paramount point - the desire for logical data independence. I interpret the meaning of this in an algebra to be that substituting some non-logical aspect of an implementation for another will not require any logical aspects to be... more »
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A different definition of MINUS, Part 3
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In the original exchange ( [link] ), Date says: "the operation DELETE SSP WHERE S# = S#('S1') AND P# = P#('P1') ; is inherently unsafe, since we presumably don't know, in general, whether there are any other shipments for supplier S1." Any time Date says something, I think those of us laymen must pay... more »
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A different definition of MINUS, Part 2
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Part Two In Part One, I took the Tutorial D MINUS definition, substituted names that seem a little more evocative to me, then removed the "same heading" proviso, then made the headings explicit, then made some precedence and associativity assumptions for readability purposes only, then assumed that R = A <AND> B, then showed (I hope) that an algebraic... more »
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