CS6400 - Exam Questions Solved 100%
Correct | Verified Answers
minimal cover - ✔✔E is a minimal set of dependencies that is equivalent to E . a set
of dependencies in a standard or canonical form and with no redundancies.
universal relation assumption - ✔✔states that every attribute name is unique
D (decomposition ) - ✔✔is called a decomposition of R. decompose the universal
relation schema R into a set of relation schemas D = {R1, R2, ... , Rm} that will become the
relational database schema
attribute preservation - ✔✔make sure that each attribute in R will appear in at least
one relation schema Ri in the decomposition so that no attributes are lost
dependency preserving - ✔✔union of the projections of F on each Ri in D is equivalent to F; that is, ((πR1(F)) ∪ K ∪ (πRm(F)))+ = F+.
projection of F on Ri, - ✔✔πRi(F) where Ri is a subset of R, is the set of dependencies X → Y in F+ such that the attributes in X ∪ Y are all contained in Ri
lossless joins guarantee - ✔✔the join filed must be a key in at least one of the relations
lossless - ✔✔refers to loss of information, not to loss of tuples
,counterexample - ✔✔a relation state r of R that satisfies the dependencies in F but does
not satisfy the nonadditive join condition.
-proves that D does not have the nonadditive join property with respect to F.
Binary Decomposition - ✔✔—decomposition of a relation R into two relations
Primary storage - ✔✔provides fast access to data but is of limited storage capacity. can
be operated on directly by the computer's central processing unit (CPU)
Secondary storage - ✔✔magnetic disks
flash memories
solid-state drive (SSD)
Tertiary storage - ✔✔Optical disks (CD-ROMs, DVDs, and other similar storage media).
Data in secondary or tertiary storage cannot be processed directly by the CPU
cache memory - ✔✔a static RAM (random access memory); used by the CPU to speed
up execution of program using techniques such as prefetching and pipelining
main memory - ✔✔main work area for the CPU for keeping program instructions and
data; RAM is volatile, fast, small and expensive
DRAM - ✔✔Programs reside and execute in dynamic random-access memory
main memory databases - ✔✔entire databases can be kept in main memory (with a
backup copy on magnetic disk)
, flash memory - ✔✔fast access speed, high-density, high-performance memories, using
EEPROM (electrically erasable programmable read-only memory) technology. Between
DRAM and magnetic disk storage, another form of memor
Optical Drives - ✔✔CDs (compact disks) and DVDs
Optical jukebox memories - ✔✔use an array of CD-ROM platters, which are loaded
onto drives on demand.
Tertiary Storage - ✔✔type of computer storage device that typically consists of
magnetic tape (HDD, etc. )
magnetic tapes - ✔✔are used for archiving and backup storage of data.
Tape jukeboxes - ✔✔popular as tertiary storage to hold terabytes of data
Persistent Data - ✔✔data that must persist over long periods of time; accessed
and processed repeatedly during the storage period.
transient data - ✔✔persists for only a limited time during program execution
volatile storage - ✔✔main memory
nonvolatile storage - ✔✔Permanent storage, as in read-only memory.
Most databases are stored permanently (or persistently) on magnetic disk secondary storage: -
✔✔1) databases are too large to fit entirely in main memory
2) the circumstances that cause permanent loss of stored data arise less frequently for
disk secondary storage than for primary storage
Correct | Verified Answers
minimal cover - ✔✔E is a minimal set of dependencies that is equivalent to E . a set
of dependencies in a standard or canonical form and with no redundancies.
universal relation assumption - ✔✔states that every attribute name is unique
D (decomposition ) - ✔✔is called a decomposition of R. decompose the universal
relation schema R into a set of relation schemas D = {R1, R2, ... , Rm} that will become the
relational database schema
attribute preservation - ✔✔make sure that each attribute in R will appear in at least
one relation schema Ri in the decomposition so that no attributes are lost
dependency preserving - ✔✔union of the projections of F on each Ri in D is equivalent to F; that is, ((πR1(F)) ∪ K ∪ (πRm(F)))+ = F+.
projection of F on Ri, - ✔✔πRi(F) where Ri is a subset of R, is the set of dependencies X → Y in F+ such that the attributes in X ∪ Y are all contained in Ri
lossless joins guarantee - ✔✔the join filed must be a key in at least one of the relations
lossless - ✔✔refers to loss of information, not to loss of tuples
,counterexample - ✔✔a relation state r of R that satisfies the dependencies in F but does
not satisfy the nonadditive join condition.
-proves that D does not have the nonadditive join property with respect to F.
Binary Decomposition - ✔✔—decomposition of a relation R into two relations
Primary storage - ✔✔provides fast access to data but is of limited storage capacity. can
be operated on directly by the computer's central processing unit (CPU)
Secondary storage - ✔✔magnetic disks
flash memories
solid-state drive (SSD)
Tertiary storage - ✔✔Optical disks (CD-ROMs, DVDs, and other similar storage media).
Data in secondary or tertiary storage cannot be processed directly by the CPU
cache memory - ✔✔a static RAM (random access memory); used by the CPU to speed
up execution of program using techniques such as prefetching and pipelining
main memory - ✔✔main work area for the CPU for keeping program instructions and
data; RAM is volatile, fast, small and expensive
DRAM - ✔✔Programs reside and execute in dynamic random-access memory
main memory databases - ✔✔entire databases can be kept in main memory (with a
backup copy on magnetic disk)
, flash memory - ✔✔fast access speed, high-density, high-performance memories, using
EEPROM (electrically erasable programmable read-only memory) technology. Between
DRAM and magnetic disk storage, another form of memor
Optical Drives - ✔✔CDs (compact disks) and DVDs
Optical jukebox memories - ✔✔use an array of CD-ROM platters, which are loaded
onto drives on demand.
Tertiary Storage - ✔✔type of computer storage device that typically consists of
magnetic tape (HDD, etc. )
magnetic tapes - ✔✔are used for archiving and backup storage of data.
Tape jukeboxes - ✔✔popular as tertiary storage to hold terabytes of data
Persistent Data - ✔✔data that must persist over long periods of time; accessed
and processed repeatedly during the storage period.
transient data - ✔✔persists for only a limited time during program execution
volatile storage - ✔✔main memory
nonvolatile storage - ✔✔Permanent storage, as in read-only memory.
Most databases are stored permanently (or persistently) on magnetic disk secondary storage: -
✔✔1) databases are too large to fit entirely in main memory
2) the circumstances that cause permanent loss of stored data arise less frequently for
disk secondary storage than for primary storage
