CS 6400 EXAM 3 LATEST 2025-2026 UPDATE
QUESTIONS AND ANSWERS
attribute preservation - Answer-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 - Answer-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, - Answer-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 - Answer-the join filed must be a key in at least
one of the relations
lossless - Answer-refers to loss of information, not to loss of tuples
counterexample - Answer-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 - Answer-—decomposition of a relation R into
two relations
Primary storage - Answer-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 - Answer-magnetic disks
flash memories
solid-state drive (SSD)
Tertiary storage - Answer-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 - Answer-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 - Answer-main work area for the CPU for keeping
program instructions and data; RAM is volatile, fast, small and
expensive
, DRAM - Answer-Programs reside and execute in dynamic random-
access memory
main memory databases - Answer-entire databases can be kept in main
memory (with a backup copy on magnetic disk)
flash memory - Answer-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 - Answer-CDs (compact disks) and DVDs
Optical jukebox memories - Answer-use an array of CD-ROM platters,
which are loaded onto drives on demand.
Tertiary Storage - Answer-type of computer storage device that
typically consists of magnetic tape (HDD, etc. )
magnetic tapes - Answer-are used for archiving and backup storage of
data.
Tape jukeboxes - Answer-popular as tertiary storage to hold terabytes of
data
, Persistent Data - Answer-data that must persist over long periods of
time; accessed and processed repeatedly during the storage period.
transient data - Answer-persists for only a limited time during program
execution
volatile storage - Answer-main memory
nonvolatile storage - Answer-Permanent storage, as in read-only
memory.
Most databases are stored permanently (or persistently) on magnetic
disk secondary storage: - Answer-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
3) the cost of storage per unit of data is an order of magnitude less for
disk secondary storage than for primary storage
Files of records - Answer-What the higher levels of the DBSM I/O
operates on, in addition to records. A file is a collection of pages, each
containing a collection of records. A file must support
- insert/delete/modify record
- read a particular record (specified with an rid)
- scan all records
QUESTIONS AND ANSWERS
attribute preservation - Answer-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 - Answer-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, - Answer-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 - Answer-the join filed must be a key in at least
one of the relations
lossless - Answer-refers to loss of information, not to loss of tuples
counterexample - Answer-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 - Answer-—decomposition of a relation R into
two relations
Primary storage - Answer-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 - Answer-magnetic disks
flash memories
solid-state drive (SSD)
Tertiary storage - Answer-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 - Answer-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 - Answer-main work area for the CPU for keeping
program instructions and data; RAM is volatile, fast, small and
expensive
, DRAM - Answer-Programs reside and execute in dynamic random-
access memory
main memory databases - Answer-entire databases can be kept in main
memory (with a backup copy on magnetic disk)
flash memory - Answer-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 - Answer-CDs (compact disks) and DVDs
Optical jukebox memories - Answer-use an array of CD-ROM platters,
which are loaded onto drives on demand.
Tertiary Storage - Answer-type of computer storage device that
typically consists of magnetic tape (HDD, etc. )
magnetic tapes - Answer-are used for archiving and backup storage of
data.
Tape jukeboxes - Answer-popular as tertiary storage to hold terabytes of
data
, Persistent Data - Answer-data that must persist over long periods of
time; accessed and processed repeatedly during the storage period.
transient data - Answer-persists for only a limited time during program
execution
volatile storage - Answer-main memory
nonvolatile storage - Answer-Permanent storage, as in read-only
memory.
Most databases are stored permanently (or persistently) on magnetic
disk secondary storage: - Answer-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
3) the cost of storage per unit of data is an order of magnitude less for
disk secondary storage than for primary storage
Files of records - Answer-What the higher levels of the DBSM I/O
operates on, in addition to records. A file is a collection of pages, each
containing a collection of records. A file must support
- insert/delete/modify record
- read a particular record (specified with an rid)
- scan all records
