How are keys stored and retrieved what happens when

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ample, (Sex=Male)^(SAT<620 v GP<3.0) In pictures CharacterisBc funcBon : selects rows as funcBon of aMribute values in columns, Example, (Sex=Male)^(SAT<620 v GP<3.0) StaBsBcal queries r.e. numeric evaluaBon of # rows In pictures # unique possible values Example StaBsBc funcBons ProtecBon •  Databases will oXen refuse to give answers to queries if the number of records involved are too small •  Enough? Inference Problem •  Determine confidenBal informaBon about individual enBBes represented in SDB •  e.g., Compute the president's salary 39 Query Size RestricBon Previous example shows danger of basing staBsBcs on query set that is too large SomeBmes a limitaBon is given that bounds from both sides. q( c ) permiMed only if...
View Full Document

This note was uploaded on 02/03/2014 for the course ECE 422 taught by Professor Nicol during the Fall '08 term at University of Illinois, Urbana Champaign.

Ask a homework question - tutors are online