Delete CT3532 exam materials
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- 4 questions, do 3
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- same type of questions as previous years
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- overlap in terms of style with exercise sheets
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- most questions have 3 parts with different marks
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1. question 1: design (first topic covered)
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a) functional dependencies minimal cover sets (problem based)
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b) normalisation to BCNF (discursive/descriptive)
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c) denormalisation (discursive/descriptive)
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- key things to know in general:
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- functional dependency
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- axioms to generate new functional dependencies
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- minimal cover sets
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- normal forms
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- redundancy / denormalisation
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2. question 2: transactions
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a) discuss one of problems (only 3 (think lost update problem etc not sure)) (supposedly easy)
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b) concurrency control protocol to apply to above problem, such as timestamping, two phase locking etc.
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c) distributed databases, how do we manage recovery or two phase locking or something
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- problems that arise: concurrency control, lost update, etc
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- serialisability, guarantee serialisability
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- recovery, system log
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- distributive databases
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4. question 4: database models
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a) parallelism
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b) deductive / logic databases (not covered on past papers) (not too hard because we didn't spend long on it)
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- store facts and relations
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c) security (one of the models touched on 2023-11-14) (not covered on past papers)
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- Bell-LaPadula model or some other model touched on
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- old course was called ct332
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- will get deductive / logic databases on old papers
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- no more exam material after ./slides/DatabaseSecurity.pdf
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Types of conflicts:
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- rw
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- wr
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- ww
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Conflicts in timestamping are directed: the second of the transactions is said to conflict with the first, not vice-versa.
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When a cycle is formed in the transaction graph, the transaction is killed.
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BCNF: all determinants (left-hand sides of FDs) are candidate keys
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AB -> C
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C -> B
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C+ = {C, B} != R
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Minimal cover set:
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1. RHS should be singletons
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i.e. X -> YZ becomes X->Y X->Z
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2. minimal LHS
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i.e XYZ -> W and YZ -> W then XYZ->W is redundant and should just be replaced with YZ->W
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3. No redundant FDs
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in general, use an example of your own rather than given
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- "as far as he knows", it's all examples from your own imagination"
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