DATABASE
MANAGEMENT SYSTEMS
TWO
MARKS:
UNIT:
1
INTRODUCTION
AND CONCEPTUAL MODELLING
1.
Define database management system?
Database
management system (DBMS) is a collection of interrelated data and a
set of
programs to access those data.
2.
List any eight applications of DBMS.
a) Banking
b) Airlines
c)
Universities
d) Credit card
transactions
e) Tele
communication
f) Finance
g) Sales
h)
Manufacturing
i) Human
resources
3.
What are the disadvantages of file processing system?
The disadvantages
of file processing systems are
a) Data
redundancy and inconsistency
b) Difficulty
in accessing data
c) Data
isolation
d) Integrity
problems
e) Atomicity
problems
f) Concurrent
access anomalies
4.
What are the advantages of using a DBMS?
The advantages
of using a DBMS are
a) Controlling
redundancy
b) Restricting
unauthorized access
c) Providing
multiple user interfaces
d) Enforcing
integrity constraints.
e) Providing
back up and recovery
5.
Give the levels of data abstraction?
a) Physical
level
b) logical
level
c) view level
6.
Define instance and schema?
Instance:
Collection of data stored in the data base at a particular moment
is
called an
Instance of the database.
Schema:
The overall design of the data base is called the data base
schema.
7.
Define the terms 1) physical schema 2) logical schema.
Physical
schema: The physical schema describes the database
design at the
physical
level, which is the lowest level of abstraction describing how the data are
actually
stored.
Logical
schema: The logical schema describes the database
design at the logical
level, which
describes what data are stored in the database and what relationship exists
among the
data.
8.
What is conceptual schema?
The schemas at
the view level are called subschemas that describe different views
of the
database.
9.
Define data model?
A data model
is a collection of conceptual tools for describing data, data
relationships,
data semantics and consistency constraints.
10.
What is storage manager?
A storage
manager is a program module that provides the interface between the
low level data
stored in a database and the application programs and queries submitted to
the system.
11.
What are the components of storage manager?
The storage
manager components include
a)
Authorization and integrity manager
b) Transaction
manager
c) File
manager
d) Buffer
manager
12.
What is the purpose of storage manager?
The storage
manager is responsible for the following
a) Interaction
with he file manager
b) Translation
of DML commands in to low level file system commands
c) Storing,
retrieving and updating data in the database
13. List
the data structures implemented by the storage manager.
The storage
manager implements the following data structure
a) Data files
b) Data
dictionary
c) indices
14.
What is a data dictionary?
A data
dictionary is a data structure which stores meta data about the structure of
the database
ie. the schema of the database.
15.
What is an entity relationship model?
The entity
relationship model is a collection of basic objects called entities and
relationship
among those objects. An entity is a thing or object in the real world that is
distinguishable
from other objects.
16.
What are attributes? Give examples.
An entity is
represented by a set of attributes. Attributes are descriptive properties
possessed by
each member of an entity set.
Example:
possible attributes of customer entity are customer name, customer
id,
customer
street, customer city.
17.
What is relationship? Give examples
A relationship
is an association among several entities.
Example:
A depositor relationship associates a customer with each account
that
he/she has.
18.
Define the terms
i)
Entity set
ii)
Relationship set
Entity
set: The set of all entities of the same type is
termed as an entity set.
Relationship
set: The set of all relationships of the same type is termed as a
relationship
set.
19.
Define single valued and multivalued attributes.
Single
valued attributes: attributes with a single value for a
particular entity are
called single
valued attributes.
Multivalued
attributes: Attributes with a set of value for a
particular entity are
called
multivalued attributes.
20.
What are stored and derived attributes?
Stored
attributes: The attributes stored in a data base are
called stored attributes.
Derived
attributes: The attributes that are derived from the
stored attributes are
called derived
attributes.
21.
What are composite attributes?
Composite
attributes can be divided in to sub parts.
22.
Define null values.
In some cases
a particular entity may not have an applicable value for an attribute
or if we do
not know the value of an attribute for a particular entity. In these cases null
value is used.
23.
Define the terms
i)
Entity type
ii)
Entity set
Entity
type: An entity type defines a collection of
entities that have the same
attributes.
Entity
set: The set of all entities of the same type is
termed as an entity set.
24.
What is meant by the degree of relationship set?
The degree of
relationship type is the number of participating entity types.
25.
Define the terms
i)
Key attribute
ii)
Value set
Key
attribute: An entity type usually has an attribute
whose values are distinct
from each
individual entity in the collection. Such an attribute is called a key
attribute.
Value
set: Each simple attribute of an entity type is
associated with a value set
that specifies
the set of values that may be assigned to that attribute for each individual
entity.
26.
Define weak and strong entity sets?
Weak entity
set: entity set that do not have key attribute of their own are called
weak entity
sets.
Strong entity
set: Entity set that has a primary key is termed a strong entity set.
27.
What does the cardinality ratio specify?
Mapping
cardinalities or cardinality ratios express the number of entities to which
another entity
can be associated. Mapping cardinalities must be one of the
following:
• One
to one
• One
to many
• Many
to one
• Many
to many
28.
Explain the two types of participation constraint.
• Total:
The participation of an entity set E in a relationship set R is
said to
be total
if every entity in E participates in at least one relationship in
R.
• Partial:
if only some entities in E participate in relationships in R, the
participation
of entity set E in relationship R is said to be partial.
29.
Define the terms
i)
DDL
ii)
DML
DDL:
Data base schema is specified by a set of definitions expressed by
a special
language
called a data definition language.
DML:
A data manipulation language is a language that enables users to
access or
manipulate
data as organized by the appropriate data model.
30.
Write short notes on relational model
The relational
model uses a collection of tables to represent both data and the
relationships
among those data. The relational model is an example of a record
based model.
31.
Define tuple and attribute
• Attributes:
column headers
• Tuple:
Row
32. Define
the term relation.
Relation is a
subset of a Cartesian product of list domains.
33.
Define tuple variable
Tuple variable
is a variable whose domain is the set of all tuples.
34.
Define the term Domain.
For each
attribute there is a set of permitted values called the domain
of that
attribute.
35.
What is a candidate key?
Minimal super
keys are called candidate keys.
36.
What is a primary key?
Primary
key is chosen by the database designer as the
principal means of
identifying an
entity in the entity set.
37.
What is a super key?
A super
key is a set of one or more attributes that
collectively allows us to
identify
uniquely an entity in the entity set.
38.
Define- relational algebra.
The relational
algebra is a procedural query language. It consists of a set of
operations
that take one or two relation as input and produce a new relation as
output.
39.
What is a SELECT operation?
The select
operation selects tuples that satisfy a given
predicate. We use the
lowercase
letter s to denote selection.
40.
What is a PROJECT operation?
The project
operation is a unary operation that returns its argument relation with
certain
attributes left out. Projection is denoted by pie (p).
41.
Write short notes on tuple relational calculus.
The tuple
relational calculation is anon procedural query language. It describes
the desired
information with out giving a specific procedure for obtaining that
information.
A query or
expression can be expressed in tuple relational calculus as
{t | P
(t)}
which means
the set of all tuples‘t’ such that predicate P is true for‘t’.
Notations used:
• t[A]
® the value of tuple ‘t’ on attribute, A
• t
Î r ® tuple
‘t’ is in relation ‘r’
• $ ® there
exists
Definition for
‘there exists’ ($):
$ t
Î r(Q(t))
which means
there exists a tuple ‘t’ in relation ‘r’
such that
predicate Q(t) is true.
• " ® for
all
Definition for
‘for all’ ("):
"t
Î r(Q(t))
which means
Q(t) is true for all tuples ‘t’ in relation
‘r’.
• _
® Implication
Definition for
Implication (_):
P_Q
means if P is true then Q must be true.
42.
Write short notes on domain relational calculus
The domain
relational calculus uses domain variables that take on values from an
attribute
domain rather than values for entire tuple.
43.
Define query language?
A query is a
statement requesting the retrieval of information. The portion of
DML that involves
information retrieval is called a query language.
44.
Write short notes on Schema diagram.
A database
schema along with primary key and foreign key dependencies can be
depicted
pictorially by schema diagram. Each relation appears as a box with
attributes
listed inside it and the relation name above it.
45.
What is foreign key?
A relation
schema r1 derived from an ER schema may include among its
attributes the
primary key of another relation schema r2.this attribute is called a foreign
key
from r1 referencing r2.
UNIT:
2
RELATIONAL
MODEL
1.
What are the parts of SQL language?
The SQL
language has several parts:
_ data
- definitition language
_ Data
manipulation language
_ View
definition
_ Transaction
control
_ Embedded
SQL
_ Integrity
_ Authorization
2.
What are the categories of SQL command?
SQL commands
are divided in to the following categories:
1. data -
definitition language
2. data
manipulation language
3. Data Query
language
4. data
control language
5. data
administration statements
6. transaction
control statements
3.
What are the three classes of SQL expression?
SQL expression
consists of three clauses:
_ Select
_ From
_ where
4.
Give the general form of SQL query?
Select
A1, A2………….,
An
From
R1, R2……………,
Rm
Where
P
5.
What is the use of rename operation?
Rename
operation is used to rename both relations and a attributes.
It uses the as
clause, taking the form:
Old-name as
new-name
6.
Define tuple variable?
Tuple
variables are used for comparing two tuples in the same relation. The tuple
variables are
defined in the from clause by way of the as
clause.
7.
List the string operations supported by SQL?
1) Pattern
matching Operation
2)
Concatenation
3) Extracting
character strings
4) Converting
between uppercase and lower case letters.
8.
List the set operations of SQL?
1) Union
2) Intersect
operation
3) The except
operation
9.
What is the use of Union and intersection operation?
Union:
The result of this operation includes all tuples that are either in r1 or in r2
or in both r1
and r2.Duplicate tuples are automatically eliminated.
Intersection:
The result of this relation includes all tuples that are in both
r1 and
r2.
10.
What are aggregate functions? And list the aggregate functions supported by
SQL?
Aggregate
functions are functions that take a collection of values as input and
return a
single value.
Aggregate
functions supported by SQL are
_ Average:
avg
_ Minimum:
min
_ Maximum:
max
_ Total:
sum
_ Count:
count
11.
What is the use of group by clause?
Group
by clause is used to apply aggregate functions to a set of tuples.The
attributes
given in the group by clause are
used to form groups.Tuples with the
same value on
all attributes in the group by clause are
placed in one group.
12.
What is the use of sub queries?
A sub query is
a select-from-where expression that is nested with in another
query. A
common use of sub queries is to perform tests for set membership, make
setcomparisions,
and determine set cardinality.
13.
What is view in SQL? How is it defined?
Any relation
that is not part of the logical model, but is made visible to a user as a
virtual
relation is called a view.
We define view
in SQL by using the create view command. The
form of the
create
view command is
Create
view v as <query
expression>
14.
What is the use of with clause in SQL?
The with
clause provides a way of defining a temporary view whose
definition is
available only
to the query in which the with clause
occurs.
15.
List the table modification commands in SQL?
_ Deletion
_ Insertion
_ Updates
_ Update
of a view
16.
List out the statements associated with a database transaction?
_ Commit
work
_ Rollback
work
17.
What is transaction?
Transaction is
a unit of program execution that accesses and possibly updated
various data
items.
18.
List the SQL domain Types?
SQL supports
the following domain types.
1) Char(n) 2)
varchar(n) 3) int 4) numeric(p,d)
5) float(n) 6)
date.
19.
What is the use of integrity constraints?
Integrity
constraints ensure that changes made to the database by authorized users
do not result
in a loss of data consistency. Thus integrity constraints guard against
accidental
damage to the database.
20.
Mention the 2 forms of integrity constraints in ER model?
_ Key
declarations
_ Form
of a relationship
21.
What is trigger?
Triggers are
statements that are executed automatically by the system as the side
effect of a
modification to the database.
22.
What are domain constraints?
A domain is a
set of values that may be assigned to an attribute .all values that
appear in a
column of a relation must be taken from the same domain.
23.
What are referential integrity constraints?
A value that
appears in one relation for a given set of attributes also appears for a
certain set of
attributes in another relation.
24.
What is assertion? Mention the forms available.
An assertion
is a predicate expressing a condition that we wish the database
always to
satisfy.
_ Domain
integrity constraints.
_ Referential
integrity constraints
25.
Give the syntax of assertion?
Create
assertion <assertion name>check<predicate>
26. What is
the need for triggers?
Triggers are
useful mechanisms for alerting humans or for starting certain tasks
automatically
when certain conditions are met.
27.
List the requirements needed to design a trigger.
The
requirements are
_ Specifying
when a trigger is to be executed.
_ Specify
the actions to be taken when the trigger executes.
28.
Give the forms of triggers?
_ The
triggering event can be insert or delete.
_ For
updated the trigger can specify columns.
_ The
referencing old row as clause
_ The
referencing new row as clause
_ The
triggers can be initiated before the event or after the event.
29.
What does database security refer to?
Database
security refers to the protection from unauthorized access and malicious
destruction or
alteration.
30.
List some security violations (or) name any forms of malicious access.
_ Unauthorized
reading of data
_ Unauthorized
modification of data
_ Unauthorized
destruction of data.
31.
List the types of authorization.
_ Read
authorization
_ Write
authorization
_ Update
authorization
_ Drop
authorization
32.
What is authorization graph?
Passing of
authorization from one user to another can be represented by an
authorization
graph.
33.
List out various user authorization to modify the database schema.
_ Index
authorization
_ Resource
authorization
_ Alteration
authorization
_ Drop
authorization
34.
What are audit trails?
An audit trail
is a log of all changes to the database along with information such
as which user
performed the change and when the change was performed.
35.
Mention the various levels in security measures.
_ Database
system
_ Operating
system
_ Network
_ Physical
_ human
36.
Name the various privileges in SQL?
_ Delete
_ Select
_ Insert
_ update
37.
Mention the various user privileges.
_ All
privileges directly granted to the user or role.
_ All
privileges granted to roles that have been granted to the user or role.
38.
Give the limitations of SQL authorization.
_ The
code for checking authorization becomes intermixed with the rest of the
application
code.
_ Implementing
authorization through application code rather than specifying it
declaratively
in SQL makes it hard to ensure the absence of loopholes.
39.
Give some encryption techniques?
_ DES
_ AES
_ Public
key encryption
40.
What does authentication refer?
Authentication
refers to the task of verifying the identity of a person.
41.
List some authentication techniques.
_ Challenge
response scheme
_ Digital
signatures
_ Nonrepudiation
42.
Define Boyce codd normal form
A relation
schema R is in BCNF with respect to a set F of functional
dependencies
if, for all functional dependencies in F
+
of the form. _->_,
where _
43.
List the disadvantages of relational database system
_ Repetition
of data
_ Inability
to represent certain information.
44.
What is first normal form?
The domain of
attribute must include only atomic (simple, indivisible) values.
45.
What is meant by functional dependencies?
Consider a
relation schema R and _ C R
and _ C R. The functional
dependency _
_ _
holds on relational schema R if in any legal relation r(R), for
all pairs of
tuples t1 and
t2 in r such that t1 [_] =t1 [_],
and also t1 [_] =t2 [_].
46.
What are the uses of functional dependencies?
_ To
test relations to see whether they are legal under a given set of functional
dependencies.
_ To
specify constraints on the set of legal relations.
47.
Explain trivial dependency?
Functional
dependency of the form _ _ _
is trivial if _ C
_. Trivial functional
dependencies
are satisfied by all the relations.
48.
What are axioms?
Axioms or
rules of inference provide a simpler technique for reasoning about
functional
dependencies.
49.
What is meant by computing the closure of a set of functional dependency?
The closure of
F denoted by F+ is the set of
functional dependencies logically
implied by F.
50.
What is meant by normalization of data?
It is a
process of analyzing the given relation schemas based on their Functional
Dependencies
(FDs) and primary key to achieve the properties
_ Minimizing
redundancy
_ Minimizing
insertion, deletion and updating anomalies.
51.
Define canonical cover?
A canonical
cover Fc for F is a set of dependencies such that F
logically implies
all
dependencies in FC and Fc
logically implies all dependencies in F. Fc
must
have the
following properties.
52.
List the properties of canonical cover.
Fc
must have the following properties.
_ No
functional dependency in Fc contains an
extraneous attribute.
_ Each
left side of a functional dependency in Fc is
unique.
53.
Explain the desirable properties of decomposition.
_ Lossless-join
decomposition
_ Dependency
preservation
_ Repetition
of information
54.
What is 2NF?
A relation
schema R is in 2NF if it is in 1NF and every non-prime attribute A in R
is fully
functionally dependent on primary key.
UNIT:
3
DATA
STORAGE AND QUERY PROCESSING
1. What
is an index?
An index is a
structure that helps to locate desired records of a relation quickly,
without
examining all records
.
2. Define
query optimization.
Query
optimization refers to the process of finding the lowest –cost method of
evaluating a
given query.
3. What
are called jukebox systems?
Jukebox
systems contain a few drives and numerous disks that can be loaded into
one of the
drives automatically.
4. What
are the types of storage devices?
_ Primary
storage
_ Secondary
storage
_ Tertiary
storage
_ Volatile
storage
_ Nonvolatile
storage
5.
What is called remapping of bad sectors?
If the
controller detects that a sector is damaged when the disk is initially
formatted, or
when an attempt is made to write the sector, it can logically map the sector
to a different
physical location.
6.
Define access time.
Access time is
the time from when a read or write request is issued to when data
transfer
begins.
7.
Define seek time.
The time for
repositioning the arm is called the seek time and it increases with the
distance that
the arm is called the seek time.
8.
Define average seek time.
The average
seek time is the average of the seek times, measured over a sequence
of random
requests.
9.
Define rotational latency time.
The time spent
waiting for the sector to be accessed to appear under the head is
called the
rotational latency time.
10.
Define average latency time.
The average
latency time of the disk is one-half the time for a full rotation of the
disk.
11.
What is meant by data-transfer rate?
The
data-transfer rate is the rate at which data can be retrieved from or stored to
the disk.
12.
What is meant by mean time to failure?
The mean time
to failure is the amount of time that the system could run
continuously
without failure.
13.
What is a block and a block number?
A block is a
contiguous sequence of sectors from a single track of one platter.
Each request
specifies the address on the disk to be referenced. That address is in the
form of a
block number.
14.
What are called journaling file systems?
File systems
that support log disks are called journaling file systems.
15.
What is the use of RAID?
A variety of
disk-organization techniques, collectively called redundant arrays of
independent
disks are used to improve the performance and reliability.
16.
What is called mirroring?
The simplest
approach to introducing redundancy is to duplicate every disk. This
technique is
called mirroring or shadowing.
17.
What is called mean time to repair?
The mean time
to failure is the time it takes to replace a failed disk and to restore
the data on
it.
18.
What is called bit-level striping?
Data striping
consists of splitting the bits of each byte across multiple disks. This
is called
bit-level striping.
19.
What is called block-level striping?
Block level
striping stripes blocks across multiple disks. It treats the array of disks
as a large
disk, and gives blocks logical numbers.
20.
What are the two main goals of parallelism?
_ Load
–balance multiple small accesses, so that the throughput of such
accesses
increases.
_ Parallelize
large accesses so that the response time of large accesses is
reduced
.
21.
What are the factors to be taken into account when choosing a RAID level?
o Monetary
cost of extra disk storage requirements.
o Performance
requirements in terms of number of I/O operations
o Performance
when a disk has failed.
o Performances
during rebuild.
22.
What is meant by software and hardware RAID systems?
RAID can be
implemented with no change at the hardware level, using only
software
modification. Such RAID implementations are called software RAID systems
and the
systems with special hardware support are called hardware RAID systems.
23.
Define hot swapping?
Hot swapping
permits the removal of faulty disks and replaces it by new ones
without
turning power off. Hot swapping reduces the mean time to repair.
24.
What are the ways in which the variable-length records arise in database
systems?
_ Storage
of multiple record types in a file.
_ Record
types that allow variable lengths for one or more fields.
_ Record
types that allow repeating fields.
25.
What is the use of a slotted-page structure and what is the information present
in
the header?
The
slotted-page structure is used for organizing records within a single block.
The header
contains the following information.
_ The
number of record entries in the header.
_ The
end of free space
_ An
array whose entries contain the location and size of each record.
26.
What are the two types of blocks in the fixed –length representation? Define
them.
• Anchor
block: Contains the first record of a chain.
• Overflow
block: Contains the records other than those that are the first
record of a
chain.
27.
What is known as heap file organization?
In the heap
file organization, any record can be placed anywhere in the file where
there is space
for the record. There is no ordering of records. There is a single file for
each relation.
28.
What is known as sequential file organization?
In the
sequential file organization, the records are stored in sequential order,
according to
the value of a “search key” of each record.
29.
What is hashing file organization?
In the hashing
file organization, a hash function is computed on some attribute of
each record.
The result of the hash function specifies in which block of the file the record
should be
placed.
30.
What is known as clustering file organization?
In the
clustering file organization, records of several different relations are stored
in the same
file.
31.
What are the types of indices?
_ Ordered
indices
_ Hash
indices
32.
What are the techniques to be evaluated for both ordered indexing and hashing?
_ Access
types
_ Access
time
_ Insertion
time
_ Deletion
time
_ Space
overhead
33.
What is known as a search key?
An attribute
or set of attributes used to look up records in a file is called a search
key.
34.
What is a primary index?
A primary
index is an index whose search key also defines the sequential order of
the file.
35.
What are called index-sequential files?
The files that
are ordered sequentially with a primary index on the search key, are
called
index-sequential files.
36.
What are the two types of indices?
_ Dense
index
_ Sparse
index
37.
What are called multilevel indices?
Indices with
two or more levels are called multilevel indices.
38.
What is B-Tree?
A B-tree
eliminates the redundant storage of search-key values .It allows search
key values to
appear only once.
39.
What is a B+-Tree index?
A B+-Tree
index takes the form of a balanced tree in which every path from the
root of the
root of the root of the tree to a leaf of the tree is of the same length.
40.
What is a hash index?
A hash index
organizes the search keys, with their associated pointers, into a hash
file
structure.
41.
What is called query processing?
Query
processing refers to the range of activities involved in extracting data from
a database.
42.
What are the steps involved in query processing?
The basic
steps are:
_ parsing
and translation
_ optimization
_ evaluation
43.
What is called an evaluation primitive?
A relational
algebra operation annotated with instructions on how to evaluate is
called an
evaluation primitive.
44.
What is called a query evaluation plan?
A sequence of
primitive operations that can be used to evaluate ba query is a
query evaluation
plan or a query execution plan.
45.
What is called a query –execution engine?
The query
execution engine takes a query evaluation plan, executes that plan, and
returns the
answers to the query.
46.
What are called as index scans?
Search
algorithms that use an index are referred to as index scans.
47.
What is called as external sorting?
Sorting of
relations that do not fit into memory is called as external sorting.
48.
What is called as recursive partitioning?
The system
repeats the splitting of the input until each partition of the build input
fits in the
memory. Such partitioning is called recursive partitioning.
49.
What is called as an N-way merge?
The merge
operation is a generalization of the two-way merge used by the
standard
in-memory sort-merge algorithm. It merges N runs, so it is called an N-way
merge.
50.
What is known as fudge factor?
The number of
partitions is increased by a small value called the fudge factor,
which is
usually 20 percent of the number of hash partitions computed.
UNIT:
4
TRANSACTION
PROCESSING
1.
What is transaction?
Collections of
operations that form a single logical unit of work are called
transactions.
2.
What are the two statements regarding transaction?
The two
statements regarding transaction of the form:
_ Begin
transaction
_ End
transaction
3.
What are the properties of transaction?
The properties
of transactions are:
_ Atomicity
_ Consistency
_ Isolation
_ Durability
4.
What is recovery management component?
Ensuring
durability is the responsibility of a software component of the base
system called
the recovery management component.
5.
When is a transaction rolled back?
Any changes
that the aborted transaction made to the database must be undone.
Once the changes
caused by an aborted transaction have been undone, then the
transaction
has been rolled back.
6.
What are the states of transaction?
The states of
transaction are
_ Active
_ Partially
committed
_ Failed
_ Aborted
_ Committed
_ Terminated
7.
What is a shadow copy scheme?
It is simple,
but efficient, scheme called the shadow copy schemes. It is based on
making copies
of the database called shadow copies that one transaction is active at a
time. The
scheme also assumes that the database is simply a file on disk.
8.
Give the reasons for allowing concurrency?
The reasons
for allowing concurrency is if the transactions run serially, a short
transaction
may have to wait for a preceding long transaction to complete, which can lead
to
unpredictable delays in running a transaction.
So concurrent
execution reduces the unpredictable delays in running transactions.
9.
What is average response time?
The average
response time is that the average time for a transaction to be
completed
after it has been submitted.
10.
What are the two types of serializability?
The two types
of serializability is
_ Conflict
serializability
_ View
serializability
11.
Define lock?
Lock is the
most common used to implement the requirement is to allow a
transaction to
access a data item only if it is currently holding a lock on that item.
12.
What are the different modes of lock?
The modes of
lock are:
_ Shared
_ Exclusive
13.
Define deadlock?
Neither of the
transaction can ever proceed with its normal execution. This
situation is
called deadlock.
14.
Define the phases of two phase locking protocol
_ Growing
phase: a transaction may obtain locks but not release any lock.
_ Shrinking
phase: a transaction may release locks but may not obtain any new
locks.
15.
Define upgrade and downgrade?
It provides a
mechanism for conversion from shared lock to exclusive lock is
known as
upgrade.
It provides a
mechanism for conversion from exclusive lock to shared lock is
known as
downgrade.
16.
What is a database graph?
The partial
ordering implies that the set D may now be viewed as a directed
acyclic graph,
called a database graph.
17.
What are the two methods for dealing deadlock problem?
The two
methods for dealing deadlock problem is deadlock detection and
deadlock
recovery.
18.
What is a recovery scheme?
An integral
part of a database system is a recovery scheme that can restore the
database to
the consistent state that existed before the failure.
19.
What are the two types of errors?
The two types
of errors are:
_ Logical
error
_ System
error
20.
What are the storage types?
The storage
types are:
_ Volatile
storage
_ Nonvolatile
storage
21.
Define blocks?
The database
system resides permanently on nonvolatile storage, and is
partitioned
into fixed-length storage units called blocks.
22.
What is meant by Physical blocks?
The input and
output operations are done in block units. The blocks residing on
the disk are
referred to as physical blocks.
23.
What is meant by buffer blocks?
The blocks
residing temporarily in main memory are referred to as buffer blocks.
24.
What is meant by disk buffer?
The area of
memory where blocks reside temporarily is called the disk buffer.
25.
What is meant by log-based recovery?
The most
widely used structures for recording database modifications is the log.
The log is a
sequence of log records, recording all the update activities in the database.
There are
several types of log records.
26.
What are uncommitted modifications?
The
immediate-modification technique allows database modifications to be output
to the
database while the transaction is still in the active state. Data modifications
written
by active
transactions are called uncommitted modifications.
27.
Define shadow paging.
An alternative
to log-based crash recovery technique is shadow paging. This
technique
needs fewer disk accesses than do the log-based methods.
28.
Define page.
The database
is partitioned into some number of fixed-length blocks, which are
referred to as
pages.
29.
Explain current page table and shadow page table.
The key idea
behind the shadow paging technique is to maintain two page tables
during the
life of the transaction: the current page table and the shadow page table. Both
the page
tables are identical when the transaction starts. The current page table may be
changed when a
transaction performs a write operation.
30.
What are the drawbacks of shadow-paging technique?
• Commit
Overhead
• Data
fragmentation
• Garbage
collection
30.
Define garbage collection.
Garbage may be
created also as a side effect of crashes. Periodically, it is
necessary to
find all the garbage pages and to add them to the list of free pages. This
process is
called garbage collection.
32.
Differentiate strict two phase locking protocol and rigorous two phase locking
protocol.
In strict
two phase locking protocol all exclusive mode locks taken by
a
transaction is
held until that transaction commits.
Rigorous
two phase locking protocol requires that all locks be held
until the
transaction
commits.
33.
How the time stamps are implemented
• Use
the value of the system clock as the time stamp. That is a transaction’s
time stamp is
equal to the value of the clock when the transaction enters the
system.
• Use
a logical counter that is incremented after a new timestamp has been
assigned; that
is the time stamp is equal to the value of the counter.
34.
What are the time stamps associated with each data item?
• W-timestamp
(Q) denotes the largest time stamp if any transaction that
executed WRITE
(Q) successfully.
• R-timestamp
(Q) denotes the largest time stamp if any transaction that
executed READ
(Q) successfully.
UNIT:
5
CURRENT
TRENDS
1.
What is meant by object-oriented data model?
The
object-oriented paradigm is based on encapsulation of data and code related
to an object
in to a single unit, whose contents are not visible to the outside world.
2.
What is the major advantage of object-oriented programming paradigm?
The ability to
modify the definition of an object without affecting the rest of the
system is the
major advantage of object-oriented programming paradigm.
3.
What are the methods used in object-oriented programming paradigm?
*read-only
*update
4.
What is the main difference between read-only and update methods?
A read-only
method does not affect the values of a variable in an object, whereas
an update
method may change the values of the variables.
5.
What is the use of keyword ISA?
The use of
keyword ISA is to indicate that a class is a specialization of another
class.
6.
Differentiate sub-class and super-class?
The
specialization of a class is called subclasses.eg: employee is a subclass of
person and
teller is a subclass of employee.Conversely, employee is a super class
of teller, and
person is a super class of employee.
7.
What is substitutability?
Any method of
a class-say A can equally well be invoked with any object
belonging to
any subclasses B of A. This characteristic leads to code reuse, since
the messages,
methods, and functions do not have to be written again for objects
of class B.
8.
What is multiple inheritance?
Multiple
inheritance permits a class to inherit variables and methods from
multiple super
classes.
9.
What is DAG?
The
class-subclass relationship is represented by a directed acyclic graph.eg:
employees can
be temporary or permanenet.we may create subclasses temporary
and
permanenet, of the class employee.
10.
What is disadvantage of multiple inheritance?
There is potential
ambiguity if the same variable or method can be inherited from
more than one
superclass.eg: student class may have a variable dept identifying a
student's
department, and the teacher class may correspondingly have a variable
dept
identifying a teacher's department.
11.
What is object identity?
An object
retains its identity even if some or all the values of variables or
definitions of
methods change overtime.
12.
What are the several forms of identity?
*Value
*Name
*Built-in
13.
What is a value?
A data value
is used for identity. This form of identity is used in relational
systems.eg:
The primary key value of a tuple identifies the tuple.
14.
What is a Name?
A
user-supplied name is used for identity. This form of identity is used for
files in
file systems.
The user gives each file a name that uniquely identifies it, regardless
of its
contents.
15What
is a Built-in
A notation of
identity is built-into the data model or programming language and
no
user-supplied identifier is required. This form of identity is used in
objectoriented
systems.
16
What is meant by object identifiers?
Object-oriented
systems use an object identifier to identify objects. Object
identifiers
are unique: that is each object has a single identifier, and no two
objects have
the same identifier.
17.
What are composite objects?
Objects that
contain other objects are called complex objects or composite
objects.
18.
What is object containment?
References
between objects can be used to model different real-world concepts.
19.
Why containment is important in oosystems?
Containment is
an important concept in oosystems because it allows different
users to view
data at different granularities.
20.
Define object-relational systems?
Systems that
provide object-oriented extensions to relational systems are called
object-relational
systems.
21.
How persistent programming languages differ from traditional programming
languages?
Database
languages differ from traditional programming languages in that they directly
manipulate
data that are persistent-that is, data that continue to exist even after the
program
terminated. Relation in a database and tuples in a relation are examples of
persistent
data. In contrast, the only persistent data that traditional programming
languages
directly manipulate are files.
22.
Define atomic domains?
A domain is
atomic if elements of the domain are considered to be indivisible
units.
23.
Define 1NF?
First normal
form is one which requires that all attributes have atomic domains.
24.
What is nested relational model?
The nested
relational model is an extension of relational model in which domains
may be either
atomic or relation valued.
25.
List some instances of collection types?
*sets
*arrays
*multisets
26.
How to create values of structured type?
Constructor
functions are used to create values of structured types. A function
with the same
name as a structured type is a constructor function for the structured type.
27.
Write a query to define tables students and teachers as sub tables of people?
Create table
students of student under people
Create table
teachers of teacher under people
28.
What is a homogeneous distributed database?
In homogeneous
distributed databases, all sites have identical database
management
system software, are aware of one another, and agree to cooperate in
processing
user's requests.
29.
What is a heterogeneous distributed database?
In a
heterogeneous distributed database, different sites may use different schemas,
and different
dbms s/w.The sites may not be aware of one another, and they may
provide only
limited facilities for cooperation in transaction processing.
30.
What are the two approaches to store relations in distributed database?
*Replication
*Fragmentation
31.
What are the two different schemes for fragmenting a relation?
*horizontal
*vertical
32.
What is horizontal fragmentation?
Horizontal
fragmentation splits the relation by assuming each tuple of r to one or
more
fragments.
33.
What is vertical fragmentation?
Vertical
fragmentation splits the relation by decomposing the scheme R of
relation r.
34.
What are the various forms of data transparency?
*fragmentation
transparency
*replication
transparency
*location
transparency
35.
Define decision tree classifiers?
As the name
suggests decision tree classifiers use a tree: each leaf node has an associated
class, and
each internal node has a predicate associated with it.
16
MARK QUESTIONS
UNIT: 1
1.
EXPLAIN ABOUT DATABASE SYSTEM STRUCTURE?
Storage
manager
• Authorization
and integrity manager
• Transaction
manager
• File
manager
• Buffer
manager
Storage
manager implements several data structure as a part of physical system
implementation
• Data
function
• Data
dictionary
• Indices
The query
processor
• DDL
interpreter
• DML
• Query
evaluation engine
2.
DESCRIBE RELATIONAL MODEL?
Structure of
relational data base
_ Basic
structure
_ Database
schema
_ Keys
_ Schema
diagram
_ Query
languages
3.
BRIEFLY EXPLAIN RELATIONAL ALGEBRA?
Fundamental
operations
• Unary
operations
• Binary
operations
Select
operations
_branchname=’perryridge’
(loan)
The
project operation
_loannumber,amount
(loan)
Composition
of relational operations
• Relational
algebra expressions
Union
operations
r _
s
r and s must
be a same arity.
They must have
the same no of attributes.
The
set difference operations
r-s produce a
relation containing those tuples in r but not in s.
The
Cartesian product operations
The
rename operations
4.
WHAT IS DATA MODELS? EXPLAIN IT DETAIL?
Entity
relationship model
• Rectangles
• Ellipse
• Diamonds
• Lines
Relational
model
Relational
model use a collection of tables to represent both data and the
relationships
among those data. Each table has a multiple columns and each columns has
unique name
Other
data models
• Object
oriented data model
• Object
relational data model
• Network
data model
• Hierarchical
data model
5.
BRIEFLY DESCRIBE RELATIONAL CALCULUS?WITH SOME
EXAMPLES?
The
tuple relational calculus
A query in a
tuple relational calculus is expressed as
{t| P(t)}
• Example
Queries
• Formal
definition
• Safety
of expressions
• Expressive
power of languages
The
domain relational calculus
• Example
Queries
• Formal
definition
• Safety
of expressions
• Expressive
power of languages
UNIT-2
1.
DESCRIBE INTEGRITY AND SECURITY?
• Domain
constraint
Referential
integrity
A value that
appears in one relation for a given set of attributes also appear
for a certain
set of attributes in another relation. This condition is called referential
integrity.
• Referential
integrity and E-R models
• Database
modification
• Referential
integrity in SQL
2.
WHAT IS AGGREGATE FUNCTION?BRIEFLY DESCRIBE IT?
Aggregate
functions are functions that take a collection of values as input and
return a
single value. SQL offers 5 built-in aggregate functions:
• Average:
avg
• Minimum:min
• Maximum:
max
• Total:sum
• Count:count
Average: avg
Select
avg (balance)
From
account
Where
branch-name=’perryridge’
Count :count
select
branch-name,count(distinct
customer-name)
from
depositior,account
where
depositor.account-number=account.account-number
groupby
branch-name
3.
WHAT IS DATA DEFINITION LANGUAGE?EXPLAIN IT IN DETAIL?
The SQL DDL
allows specification of not only a set of relations, but also
information
after each relation, including
• The
schema for each relation
• The
domain of values associated with each attribute
• The
integrity constraints
• The
set of indices to be maintained for each relation
• The
security and authorization information for each relation
• The
physical storage structure of each relation on disk
Domain
Types in SQL
Char(n),
varchar(n),
int, small int, numeric(p,d), real, double, precision,
float(n),
date, time, timestamp.
Schema
Definition in SQL
• Primary
key
• Check
4.
EXPLAIN MECHANISM OF NESTED QUERIES?
SQL provides a
mechanism for nesting subqueries.A subquery is a select from
where
expression that is nested within another query. A common use of sub queries is
to
perform tests
for set membership, make set comparisons, and determine set cardinality.
• Set
membership
(select
customer-name
from
depositor)
• Set
comparison
select
distinct T.branch-name
from
branch as T,branch as S
where
T.assets > S.assets and S.branch-city=’Brooklyn’
• Test
for Empty Relations
Select
customer-name
from
borrower
where
exits (select *
from
depositor
where
depositor.customername=
borrower.customer-name)
• Test
for the Absence of Duplicate Tuples
5.
WRITE SHORT NOTES ON MODIFICTION OF THE DATA BASE?
• Definition
delete
from r
where
P
• Insertion
insert
into account
values
(‘A-9732’,’perryridge’,1200)
• Updates
update
account
set
balance=balance*1.05
• Update
of a view
• Transaction
UNIT-3
1.
DESCRIBE FILE ORGANISATION?
A file is
organized logically as a sequence of records. These records are mapped
onto disk blocks.
• Fixed-Length
Records
type
deposit=record
Accountnumber:char(10);
branch
name:char(22);
balance: real;
end
• Variable
length records
*storage
of multiple record types in a file
* Record types
that allow variable lengths for one or more fields
*Record types
that allow repeating fields
_ Byte
string Representation
_ Fixed
length representation
• Reserved
space
• List
representation
2.
DEFINE RAID? BRIEFLY EXPLAIN IT?
A variety of
disk organization techniques, collectively called redundant arrays
of independent
disks (RAID)
• Improvement
of reliability via redundancy.
• Improvement
in performance via parallelism
1. Bit level
striping
2. Block level
striping
_ RAID
levels
• RAID
level 0
• RAID
level 1
• RAID
level 2(memory style error correcting code)
• RAID
level 3 (Bit interleaved parity organization)
• RAID
level 4 (Block interleaved parity organization)
• RAID
level 5 (Block interleaved distributed parity)
• RAID
level 6 (P+Q redundancy)
3WRITE
SHORT NOTES ON INDEX STRUCTURE OF FILES?
There are two
basic kinds of indices
• Ordered
indices
• Hash
indices
Each technique
must be evaluated on the basis of these factors:
• Access
types
• Access
time
• Insertion
time
• Deletion
time
• Space
overhead
_ Ordered
indices
_ Primary
index
_ Dense
and sparse indices
_ Multilevel
index
_ Index
update
_ Secondary
indices
B+-Tree
index files
B+-Tree
index structure is the most widely used of several index structures
that maintain
there efficiency despite insertion and deletion of data.
_ Structure
of B+-Tree
_ Queries
on B+-Tree
_ Update
on B+-Tree
_ B+-Tree
file organization
_ B-Tree
index files
4.
EXPLAIN HASH FILE ORGANIZATION?
Hash
functions
• The
distribution is uniform
Hash functions
assign each bucket the same number of search –key
values from
the set of all possible search-key values
• The
distributed in random
In the average
case each bucket will have nearly same no of
values
assigned to it, regardless of the actual distribution of search-key
values
Handling
of bucket overflows
• Insufficient
buckets
• Skew
Open
hashing
Under an
alternative approach called open hashing
Close
hashing
The form of
hash structure that we have just described is something
referred to as
close hashing.
Hash
indices
5.
WHAT IS MAGNETIC DISKS?EXPLAIN IT?
Magnetic disk
provides the bulk of secondary storage of modern computer
system. The
disk capacity is growing at over 50% per year. But the storage
requirements
of large applications has also been growing very fast and in some case
every faster
than the growth rate of disk capacities. A
large data base may require 100
of disks.
• Physical
characteristics of disk
Physical disks
are relatively simple. Each disc platter has a flat circular shape
We
can call magnetic disk as
• hard
disk
• Floppy
disk
The read write
head store information on a sector magnetically as reversals of
the direction
of magnetization of the magnetic material. There may be hundreds of
concentric
tracks on a disc surface, containing thousands of sectors.
Unit
4
1.
DESCRIBE LOG BASED RECOVERY
The most
usably structure for recording data base modification is the LOG
the log is a
sequence of log records recording all the update activities in the data base.
There are
several types of log records. An update log records describes a single data base
write it has
these fields
• Transaction
identifier
• Data
item identifier
• Old
value
• New
value
The various
types log records as.
• <
Ti start >. Transaction Ti
has started
• <
Ti , Tx v1,v2
> .Transaction Ti has performed
a right on data item
• <
Ti commit > Transaction Ti
has committed
• <
Ti about > Transaction Ti
has aborted
_ Deferred
data base modification
_ Immediate
data base modification
_ Check
point
_ Shadow
paging
2.
WHAT IS SERIALIZABILITY?EXPLAIN ITS TYPES?
The
data base system must control concurrent
execution
of transactions, to ensure that the data base state
remains
consistent. There are different forms of schedule
equivalence
they lead to the notions of
• Conflict
serializability
• View
serializability
Conflict
serializability
We
say that ii and I j
conflict if they are operations by different
transaction
on the same data item and at least one of these instruction is a write
operations
View
serializability
The
concept of view equivalence leads to the concept of View
serializability
we say that a schedules S is view serializable if it is view equivalent to
a
serial scheduler
3.WRITE
SHORT NOTES ON TRANSACTION STATE?
A
transaction may not always complete its execution successfully such a
transaction
is termed aborted
A
transaction must be in one of the following states
• Active
• Partially
committed
• Failed
• Aborted
• Committed
4.
BRIEFLY DESCRIBE CONCURRENCYEXECUTION?
• Lock
– based protocols
• Locks
There
are various modes in which a data item may be locked in
this
section we restrict our attention to two modes
• Shared
• Exclusive
T1
: lock – x(B );
read(B);
B:=B-50;
write(B);
unlock(B);
Lock-x(A);
read(A);
A:=A+50;
write(A);
unlock(A).
5.
EXPLAIN CONCURRENCY CONTROL?
Concurrency
control
Oracles
multiversion concurrency control differs from the
concurrency
mechanism used by some other data base vendors. Read only queries are
given a read
–consistent snapshot which is view if the data base as it existed at the
specific point
in time, containing all update that we were committed by that point in time
and not
containing any updates that were not committed at any point in time thus read
clock are not
used in read only queries don’t interfere with other data base activity in
term of
locking.
Managed
stand by data base
To ensure high
availability oracle provide a managed stand by data base
future A stand
by data base is a copy of the regular data base ie in solved on the separate
system. If a
catastrophic failure occur on the primary system, the stand by system is
activate and
take over there by minimizing effect on failure on a availability. Oracle
keeps the
stand by data base up to date by constantly applying archived redo logs that
are
shipped from
the primary data base the back up data base can be brought online in readonly
mode and used
for reporting and decision support queries
UNIT
5
1.
WRITE SHORT NOTES ON DATA WARE HOUSING?
Data ware
housing applications requires the transformation of data from many
sources into a
cohesive consistent step set of data configured appropriately for use in data
ware house
operation.
• Distributed
Transformation services
Data ware
housing is an approach to manage data in which
heterogeneous
data sources are migrated to a separate homogeneous
data base
• Online
Analytical processing services
OLAP services
provide server and client capabilities to create
and manage
multidimensional OLAP data .
2. EXPLAIN
NESTED RELATIONS?
Nested
relations
The assumption
of INF is a natural one in the bank examples we
have
considered. However, not all applications are best modeled by INF relations.
The nested
relational model is an extension of the relational model in which
domains may be
either atomic or relation valued.
We illustrate
nested relations by an example from a library. Suppose we store for
each book the
following in formations
• Book
title
• Set
of authors
• Publishers
• Set
of keywords
We can see
that if we define a relation for the preceding information, several
domains will
be monatomic
• Authors
• Keywords
• Publishers
Complex
types
Collection
and large object types
Create
table books(
…
Keyword-set setoff(varchar(20))
…
)
Structure
types
Creation
of values of complex types
3.
WHAT IS INHERITANCE? DESCRIBE IT IN DETAIL?
Inheritance
Inheritance
can be at the levels of types, or at the level of tables We first
consider
inheritance of types, then inheritance at the level of labels.
Type
inheritance
Suppose that
we have the following type definition for people
create
type person
(name varchar(20)
address varchar(20))
Table
inheritance
Create
table people of person
The
consistency requirements for sub tables are
1. Each tuple
of the sub table can correspond to at most one tuple in each of its
immediate sub
tables.
2. SQL:1999
has an additional constraint that all the tuples corresponding to each
other must be
derived from one tuple .
Overlapping
sub tables
4
WHAT ARE THE TYPES OF REFERENCE?EXPLAIN IT WITH SUITABLE
EXAMPLES?
Object
oriented language provided the ability to refer the object attribute of
the type can
be referred to the specified type. We can define the type dept with a field
name and a
field head which is reference to the type person and a table dept of the type
dept as
followed
Create
type dept(
Name varchar(20),
Head ref(person)scope
people
)
Create
table dept of dept
The table
definition must specify that the reverence is derived and must still
specify a self
referential attribute name. When interesting a tuple for dept we can then use
Insert
into dept
Values(‘CS’,’john’)
5. DESCRIBE
QUERIES WITH COMPLEX TYPES?
The present
extension of the SQL query language deal with the complex type
Let us start
with the simple example:
Find the title
and the name of the publisher of each book this query carries out the
task:
Select
title, publisher.name
From
books
• path
expression
The reference
are dereference in 1999 by the –> simple
Select
head-> name, head->address
From
dept
An expression
such as” head->name” is called the path expression.
• Collection
valued attributes
• Nesting
and unnesting
The
transformation of the nested relation in to a form with fewer
(or
no) the relation –valued attribute value is called unnesting
The
reverse process of transformation a INF relation into a
nested relation is
called nesting.
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