Database management system DBMS

• Define database management system?

            Database management system (DBMS) is a collection of interrelated data  and a  set of  
programs to access those data.

• 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

• 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

• 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

• Give the levels of data abstraction?

                        a) Physical level
b) logical level
c) view level

• 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.

• 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.

• What is conceptual schema?

            The schemas at the view level are called subschemas that describe different views          
of the database.

• Define data model?

            A data model is a collection of conceptual tools for describing data, data relationships,
data semantics and consistency constraints.

• 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.

• 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

• 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

• 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

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.
• 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.
• What are composite attributes?

            Composite attributes can be divided in to sub parts.

• 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.

• 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.
• What is meant by the degree of relationship set?

            The degree of relationship type is the number of participating entity types.

• 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.

• 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.

• 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

• 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.

• 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.

• 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.

• Define tuple and attribute

            Attributes: column headers
Tuple: Row

• Define the term relation.

            Relation is a subset of a Cartesian product of list domains.

• Define tuple variable

            Tuple variable is a variable whose domain is the set of all tuples.

• Define the term Domain.

            For each attribute there is a set of permitted values called the domain of that attribute.

• What is a candidate key?

            Minimal super keys are called candidate keys.

• 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.

• 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.

• 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.

• What is a SELECT operation?

            The select operation selects tuples that satisfy a given predicate. We use the lowercase letter 𝞂 to denote selection.

• 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 pi (π).

• Define functional depedency.

            A functional dependency is a constraint between two sets of attributes from the data base. A functional dependency , denoted by
                                                           X       Y
Between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuples that can form a relation instance r of R.R={ A1,A2,…,An}.

• Define normalization.

            Normalization of data is a process during which unsatisfactory relation schemas are decomposed by breaking up their attributes into smaller relation shemas that possess desirable properties.

• Define 1NF.

            1NF states that the domains of attributes must include only atomic values and that the value of any attribute in a tuple must be a single value from the domain of that attribute. It disallows multivalued attributes, composite attributes and their combinations.

• Define 2NF.

            A relation shema R is in 2NF if every nonprime attribute A in R is fully functionally dependent on the primary key. A functional dependency Xà Y is a full functional dependency if removal of any attribute A from X means that the dependency does not hold any more; that is, for any attribute AÎX, (X-{A})   X     Y.

• Define 3NF.

            A relation shema R is in 3NF if it is in 2NF and no nonprime attribute of R is transitively dependent on the primary key. A funtional dependency X à Y in arelation shema R is a transitive dependency if ther is a set of attributes Z that is not a subset of any key of R, and both XàY and ZàY hold.

• What is need for normalization.
• To ensure that the update anomalies do not occur.
• Normal forms provide a formal frame work for analyzing relation shemas based on their keys and on the functional dependencies among their attributes.
• A series of tests that can be carried out on individual relation schemas so that the relation database can be normalized to any degree. When a test fails , the relation violating that test must be decomposed into relations that individually meet the normalization tests.
• In what way BCNF is different from 3NF?

          A relation schema R is in BCNF if whenever a functional dependency XàY holds in R,then X is a superkey of R.The only difference between BCNF and 3NF : the 3NF allows A to be a prime if X is not a superkey, is absent from BCNF.

• Define multivalued dependency.

            Multivalued dependencies are a result of  1NF which disallowed an attribute in a tuple to have a set of values. A multivalued dependency X->->Y specified on relation schema R where X and Y are subsets of R specifies the following constraint on any relation r of R:
If two tuples t1 and t2 exist in r such that t1[x]=t2[x] then two tuples t3 and t4 should also exist in r with the following properties:

• t3[X]=t4[X]=t1[X]=t2[X]
• t3[Y]=t1[Y]=t4[Y]=t2[Y]
• t3[R-(XY)]=t2[R-(XY)]=t4[R-(XY)]=t1[R-(XY)]

• Define lossless joins (or) What is nonadditive property.

            Lossless join property or nonadditive property ensures that no spurious tuples(tuples containing wrong information) are generated when a natural join operation is applied to the relations in the decomposition.

• Explain BCNF with example(or) How to convert a relation into BCNF.

          Boyce-Codd Normal form: It is stricter than 3NF, meaning that every relation in BCNF is also in 3NF; however a relation in 3NF is not necessarily in BCNF. A relation is in BCNF if and only if every determinant is a candidate key (i.e) a relatioln schema R is in BCNF if whenever a functional dependency X->A holds in R, then X is a superkey of R

• Why are certain functional dependencies called trivial functional dependencies?

            A multivaluedd functional dependency x->>Y in R is called a trivial MVD if

• Y is subset of X or
• XUY=R

       e.g., the FD enameà> pname is trivial

Ename

Pname

 

• Why are certain functional dependencies called non-trivial functional dependencies?

            A multivalued functional dependency xà> Y in R is called a no-trivial MVD if it does not satisfy the following:

• Y is subset of X
• XUY=R

Ename

Eno

Dob

Dno

Dname

dmgrno

• What are pitfalls in relational database design?
• Repetition of informaition
• Inability to represent certain information
• Loss of information
• Explain the desirable properties of decomposition.
•  Lossless-join decomposition
•  Dependency preservation
•  Repetition of information
• 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.
• Explain trivial dependency?

            Functional dependency of the form α ->β. is trivial if α C β. Trivial functional dependencies are satisfied by all the relations.
UNIT II
SQL & QUERY OPTIMIZATION

• 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
• 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

• What are the three classes of SQL expression?

SQL expression consists of three clauses:

•  Select
•  From
•  Where
• Give the general form of SQL query?

Select  A1, A2…………., An
From  R1, R2……………, Rm
Where  P

• 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

• 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.

• List the set operations of SQL?

1) Union
2) Intersect operation
3) The except operation

• 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 andr2.

• 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
• 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.

• 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 set comparisions, and determine set cardinality.

• 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>

• 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.

• List the table modification commands in SQL?
• Deletion
• Insertion
• Updates
• Update of a view
• List out the statements associated with a database transaction?
• Commit work
• Rollback work
• What is transaction?

          Transaction is a unit of program execution that accesses and possibly updated various data items.

• 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.

• 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.

• Mention the 2 forms of integrity constraints in ER model?
• Key declarations
• Form of a relationship
• What is trigger?

          Triggers are statements that are executed automatically by the system as the side effect of a modification to the database.

• 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.

• 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.

• What is assertion? Mention the forms available.

            An assertion is a predicate expressing a condition that we wish the database always to satisfy.

• Give the syntax of assertion?

Create assertion <assertion name>check<predicate>

• What is the need for triggers?

            Triggers are useful mechanisms for alerting humans or for starting certain tasks automatically when certain conditions are met.

• 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.
• 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.
• What does database security refer to?

            Database security refers to the protection from unauthorized access and malicious destruction or alteration.

• List some security violations (or) name any forms of malicious access.
• Unauthorized reading of data
• Unauthorized modification of data
• Unauthorized destruction of data.
• List the types of authorization.
• Read authorization
• Write authorization
• Update authorization
• Drop authorization
• What is authorization graph?

          Passing of authorization from one user to another can be represented by an authorization graph.

• List out various user authorization to modify the database schema.
• Index authorization
• Resource authorization
• Alteration authorization
• Drop authorization
• 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.

• Mention the various levels in security measures.
• Database system
• Operating system
• Network
• Physical
• Human
• Name the various privileges in SQL?

• Delete
• Select
• Insert
• Update

• 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.
• 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.

• List the disadvantages of relational database system
• Repetition of data
• Inability to represent certain information.
• What do you mean by “Query Optimization”?

            Improving of the strategy for processing a query is called “Query Optimization”. It is the responsibility of the system to transform the query as entered by the user into an equivalent query which can be computed more efficiently.

• What is called query processing?

          Query processing refers to the range of activities involved in extracting data froma database.

• What are the steps involved in query processing?

The basic steps are:

• parsing and translation
• optimization
• Evaluation
• What is called an evaluation primitive?

            A relational algebra operation annotated with instructions on how to evaluate is called an evaluation primitive.

• What is called a query evaluation plan?

            A sequence of primitive operations that can be used to evaluate a query is a query evaluation plan or a query execution plan.

• 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.
UNIT III
TRANSACTION PROCESSING AND CONCURRENCY CONTROL

• What is transaction?

            Collections of operations that form a single logical unit of work are called transactions.

• What are the two statements regarding transaction?

The two statements regarding transaction of the form:

•  Begin transaction
•  End transaction
• What are the properties of transaction?

The properties of transactions are:

•  Atomicity
•  Consistency
•  Isolation
•  Durability
• What is recovery management component?

            Ensuring durability is the responsibility of a software component of the base system called the recovery management component.

• 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.

• What are the states of transaction?

The states of transaction are

• Active
• Partially committed
• Failed
• Aborted
• Committed
• Terminated
• 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.

• 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.

• 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.

 

• What are the two types of serializability?

The two types of serializability is

•  Conflict serializability
•  View serializability
• 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.

• What are the different modes of lock?

The modes of lock are:

•  Shared
•  Exclusive
• Define deadlock?

            Neither of the transaction can ever proceed with its normal execution. This situation is called deadlock.

• 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.

• 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.

• 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.

• What are the two methods for dealing deadlock problem?

            The two methods for dealing deadlock problem is deadlock detection and deadlock recovery.

• 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.

• What are the two types of errors?

The two types of errors are:

•  Logical error
•  System error
• 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.

• 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.

• 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.

• Define page.

            The database is partitioned into some number of fixed-length blocks, which are referred to as pages.

• What are the drawbacks of shadow-paging technique?
• Commit Overhead
• Data fragmentation
• Garbage collection
• Differentiate strict two phase locking protocol and rigorous two phase locking

protocol.

• 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.

• 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.
• 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 IV
TRENDS IN DATABASE TECHNOLOGY

• What are the storage types?

The storage types are:

•  Volatile storage
•  Nonvolatile storage
• Define blocks?

            The database system resides permanently on nonvolatile storage, and is  into fixed-length storage units called blocks.

• 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.

• What is meant by buffer blocks?

            The blocks residing temporarily in main memory are referred to as buffer blocks.

• What is meant by disk buffer?

            The area of memory where blocks reside temporarily is called the disk buffer.

• 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.

• What is an index?

            An index is a structure that helps to locate desired records of a relation quickly,without examining all records.

• Define query optimization.

            Query optimization refers to the process of finding the lowest –cost method of evaluating a given query.

• What are the types of storage devices?
•  Primary storage
•  Secondary storage
•  Tertiary storage
•  Volatile storage
•  Nonvolatile storage
• 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.

• Define access time.

            Access time is the time from when a read or write request is issued to when data transfer begins.

• 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.

• Define average seek time.

            The average seek time is the average of the seek times, measured over a sequence of random requests.

• 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.

• Define average latency time.

            The average latency time of the disk is one-half the time for a full rotation of the disk.

• 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.

• 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.

• 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.

• What are called journaling file systems?

            File systems that support log disks are called journaling file systems.

• 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.

• What is called mirroring?

         The simplest approach to introducing redundancy is to duplicate every disk. This technique is called mirroring or shadowing.

• 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.

• 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.

• 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

• 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.
• What are the factors to be taken into account when choosing a RAID level?
• Monetary cost of extra disk storage requirements.
• Performance requirements in terms of number of I/O operations
• Performance when a disk has failed.
• Performances during rebuild.
• 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.

• 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.

• 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.
• 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.
• 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.

• 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.

• 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.

• 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.

• What is known as clustering file organization?

            In the clustering file organization, records of several different relations are stored in the same file.

• What are the types of indices?
• Ordered indices
• Hash indices
• What are the techniques to be evaluated for both ordered indexing and hashing?
• Access types
• Access time
• Insertion time
• Deletion time
• Space overhead
• 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.

• What is a primary index?

            A primary index is an index whose search key also defines the sequential order of the file.

• 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.

• What are the two types of indices?
• Dense index
• Sparse index
• What are called multilevel indices?

          Indices with two or more levels are called multilevel indices.

• What is B-Tree?

A B-tree eliminates the redundant storage of search-key values .It allows search key values to appear only once.

• 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.

• What is a hash index?

          A hash index organizes the search keys, with their associated pointers, into a hash file structure.

• What are called as index scans?

          Search algorithms that use an index are referred to as index scans.

• What is called as external sorting?

            Sorting of relations that do not fit into memory is called as external sorting.

• 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.

• 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.

• 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  V
ADVANCED TOPICS

• What are the classifications of threats?
• Physical Threats
• Accidental error
• Unauthorized access
• Malicious misuse
• Define data mining

            Data mining is a process of extracting or mining knowledge from huge amount of data.

• What are the steps in the data mining process?

• Data cleaning
• Data integration
• Data selection
• Data transformation
• Data mining
• Pattern evaluation
• Knowledge representation

• What are the uses of statistics in data mining?

            Statistics is used to

• To estimate the complexity of a data mining problem;
• suggest which data mining techniques are most likely to be successful; and
• identify data fields that contain the most “surface information”.
• Define Data Classification.

            It is a two-step process. In the first step, a model is built describing a pre-determined set of data classes or concepts. The model is constructed by analyzing database tuples described by attributes. In the second step the model is used for classification.

• What is Association rule?

            Association rule finds interesting association or correlation relationships among a large set of data items, which is used for decision-making processes. Association rules analyzes buying patterns that are frequently associated or purchased together.

• How are association rules mined from large databases?

            Association rule mining is a two-step process.

• Find all frequent itemsets.
• Generate strong association rules from the frequent itemsets.
• Why do you need data warehouse life cycle process?

            Data warehouse life cycle approach is essential because it ensures that the project pieces are brought together in the right order and at the right time.

• What are the merits of Data Warehouse?
• Ability to make effective decisions from database
• Better analysis of data and decision support
• Discover trends and correlations that benefits business
• Handle huge amount of data.
• List some of the Data Warehouse tools?
• OLAP (Online Analytic Processing)
• ROLAP (Relational OLAP)
• End User Data Access tool
• Ad Hoc Query tool
• Data Transformation services
• Replication

 

ANAND INSTITUTE OF HIGHER TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
CS6302/DATABASE MANAGEMENT SYSTEMS
PART-B
UNIT I

• Explain in detail about file Systems Organization with example.
• Explain in detail about purpose of Database System
• What are the characteristics of database? Explain
• Explain in detail about DBMS components.
• Discuss the various disadvantages in the file system  and explain how it can be overcome by the database system.
• Explain the database system structure with a neat diagram.
• Construct an ER diagram for an employee payroll system.
• Explain the basic Relational Algebra operations with the symbol used and an example for each.
• Explain Codd's Rule .
• Explain 1NF, 2NF and 3NF and BCNF with an example.
• Explain the Boyce/Codd normal form with an example. Also state how it differs from that of 3NF.
• What are the pitfalls in relational database design?  With a suitable example, explain the role of functional dependency in the process of normalization.
• Consider the universal relation r(A,B,C,D,E,F,G,H,I,J) and the set of   FD’s. G=({A,B}à {C}à {B,D}à {E,F}, {A,D}à {G,H},  {A}à{I}, {H}à{J}) What is the key of R? Decompose R into 2NF, then 3NF relations.
• Define data model. Explain the different types of data models with relevant examples.
• Construct an ER diagram for a car insurance company that has a set of customers, each of whom owns one/more cars. Each car has associated with it zero to any number of recorded accidents. Construct appropriate tables for the above ER diagram. 
• Construct the ER diagram for hospital with a set of patients and a set of medical doctors. Associate with each patient a log of the various tests and examinations conducted.

UNIT II

• Explain in detail about database Objects.
• Write short note on the following:
  [i]Data manipulation language
  [ii]Data definition language
  [iii] Data control language
• Differentiate Static SQL and  Dynamic SQL
• Give the diagrammatic representation to indicate the basic steps in query processing.
• How to choose the best evaluation plan for query?
• How does pipelining improve query evaluation efficiency?
•  Explain in detail about Heuristics and Cost Estimates in Query Optimization.
• Let relations r1[A,B,C] and r2[C,D,E] have the following properties:

r1 has 20,000 tuple, r2 has 45,000 tuples, 25 tuples of r1 fit on one block and 30 tuples of r2 fit on the block. Estimate the number of block transfers and seeks required, using each of the following join stratesies for r1 * r2 :

• Nested loop join
• Block nested loop join   
• Merge Join                          
• Explain embedded SQL with suitable example.
• Consider the employee  database , where the primary keys are underlined.

              employee(empname,street,city)
works(empname,companyname,salary)
company(companyname,city)
manages(empname,management)
Give an expression in the relational algebra for each request.
1) Find the names of all employees who work for First Bank  Corporation.
2) Find the names, street addresses and cities of residence of all  employees who work for          First  Bank Corporation and earn more than 200000 per annum.
3) Find the names of all employees in this database who live in the same city as the        company for   which they work.
4) Find the names of all employees who earn more than every employees of small Bank             Corporation.
UNIT III

• Explain testing for Serializability with respect to concurrency control schemes. How will you  determine whether a schedule is serializable or not.
• Explain the following protocols for concurrency control:
• Lock-based protocols.
• Time stamp based protocols.
• What is concurrency Control? How is it implemented in DBMS?
• Explain the properties of transactions. Illustrate the states of  transactions.
• Briefly explain ACID property with an example.
• When do you say that the system is in deadlock? Explain
• Explain the two approaches of deadlock prevention.
• Define a transaction. Then discuss the following with relevant examples:
• A read only transaction
• A read write transaction
• An aborted transaction

UNIT IV

• Explain how the RAID system improves performance and   reliability.
• Describe the structure of B+ tree and list the characteristics  of a B+ tree.
• What are the different types of storage media?
• Discuss briefly static and dynamic hashing.
  Explain the use of index structure and explain the concept of ordered indices.
• Describe a hash file organization.
• Write a detailed note on hashing techniques.
• Describe the different types of file organization? Explain using a sketch of each of them with their advantages and disadvantages. Mention the purpose of indexing. How this can be done by B+ tree? Explain.
• Describe  the  different  methods  of  implementing variable length record.
• Explain in detail about  Distributed Databases.
• Explain in detail about Multidimensional and Parallel databases.
•  Describe in detail about spatial and multimedia databases.

UNIT V

• Describe the classification of data? Explain about Threats and Risks?
• Explain in detail about database control and types of privileges?
• Explain in detail about Cryptography?
• Describe about Statistical Databases and Distributed Databases?
• Describe the architecture Data Warehousing and Mining?
• Explain in detail about the transaction processing?
• Describe about the Association rule?
• Explain about Clustering, Information Retrieval, Relevance ranking?
• Describe about the Crawling and Indexing the Web?
• Explain about Object Oriented Databases  and XML Databases with suitable example?