DBMS
CASE: Computer aided s/w engineering, automated tools used to design database and
application programs.
Database: An organized collection of logically related data.
DBMS: A commercial software system used to define, create, maintain and provide controlled
access to database.
SDLC: s/w design life cycle (OR system design life cycle, it will be system when its an
enterprise wide solution else will be software only)
Logical Design: identifying flow of data and entities required eg. ER diagram
Physical Design: designing of database in a specific DBMS eg. Creating table.
ER Model: A logical representation of the data for an organization or for a business area.
Entity: An object or concept in the user environment about which the the organization wishes
to maintain data.
RDBMS: it is a type of DBMS in which information is stored in the form of two-dimensional
structure and the relation is maintained based on common values.
Hierarchal DBMS: when data is in tree structure. Relation is maintained by links between
common entities.
Network DBMS: when data in tree structure and there is relation (link) between siblings as
well.
Relation: It is a table with corresponding attributes (values)
Integrity Constraints:
1) Domain Constraints: set of allowed values for an attribute
2) Entity Integrity: No primary key attribute can be NULL
3) Referential Integrity: It maintains consistency among the rows of two relations. IT
states that each foreign key value must match a corresponding primary key value.
Types of anomalies:
1) Insertion
2) deletion
3) Modification
Normalization: It’s the process of decomposing relation(s) with anomalies to produce smaller,
well structured relation.
Normal Form: a state of a relation that results from applying simple rules regarding functional
dependency.
First: Removes Multivalued attributes
Second: Removes partial functional dependency
Third: Removes transitive dependency
BCNF: when key attributes depends on non-key attribute
Fourth: removes multi valued dependency.
Partial functional dependency: functional dependency in which one or more non key attributes
are functionally dependent on part of (not completely) primary key.
Transitive Dependency: It’s a functional dependency b/w two or more non key attributes.
Demoralization: Process of transforming normalized relations into unnormalized from so as to
reduce complexity of queries and increase execution time.
OPERATING SYSTEMS
Defn: It is a system program that manages the computer hardware, provides a basis for
application programming and acts as an intermediary between a user and computer hardware.
Differences OR comparison: (please try to prepare yourself esp. if OS is your AOI)
• Application program/ system program
• Cache/ buffer/ spooling
• Process/ thread
• Short term/ mid-term/ long term scheduler
• Big endian(high memory address is most significant)/ little endian (low mem = most..)
• Fork() / exec()
• Preemptive/ non-preemptive scheduling
• Turnaround time/ waiting time/ response time
Deadlock: when every process in the given set is waiting for an event that can be caused only
by another process in the set.
Necessary conditions for Deadlock:
1. Mutual Exclusion
2. Hold and wait
3. No preemption
4. circular wait
Banker’s Algorithm: It provides an algorithm for deadlock avoidance and is used in case of
resource allocation graph with multiple resource instances.
Scheduling algorithms: FCFS, SJF, Round robin
Solutions to external fragmentation:
• Compaction
• Non contiguous logical address
• Paging
Paging: it is a memory management scheme that permits the physical address space of a
process to be non-contiguous and the data is accessed using the respective page table.
Represents hardware view of memory. All pages are of same size.
Segmentation: It represents user’s view of memory. It has segments of variable size.
Virtual memory: Allowing execution of process tat may not be completely transferred into
main memory.
Page Replacement algorithm:
• FIFO: It’s the ONLY algorithm having Balady’d anomaly in it.
Balady’s anomaly: the page fault rate increases as the number of allocated frames are
increased which ideally should be otherwise (that is page fault should decrease).
• Optimal page replacement
• LRU
Thrashing: it’s a condition when CPU spends more time paging than executing processes
Buffer: memory area that stores data while it is transferred b/w two devices.
Spool: buffer that holds output for a device
Stream: a two-way connection between a device driver and a user process.
OOPs
OOP: its an implementation technique in which a program is a collection of objects, and each
object is an instance of a specific class.
Class: it’s a description of a collection of objects having common responsibility, scope, roles
and attributes.
Polymorphism: its the mechanism that helps in making a single interface for multiple
implementations.
Inheritance: a class derives some or all of the attributes and/or behavior of another class.
Encapsulation: it is the mechanism that binds together the code and the data that it manipulates
under one entity.
Abstraction: hides complex implementation details from the user and providing a iser-friendly
interface.
*For C++ refer “test your C++ skills” ONLY for theoretical questions, will try to provide the
imp page number later.
DATA STRUCTURES
Data structure: It is an organization of related pieces of information in memory to facilitates
easy access and modification. (please note difference in definition with DBMS)
Stack: it’s a dynamic collection of homogeneous or heterogeneous items arranged in LIFO
order
Queue:... FIFO
Linked List: its an linear organization of data in memory where we access values by using their
memory address.
NETWORKING
ISO/OSI (international standard organization/ open system interconnect) Layers:
• Application
• Presentation
• Session
• Transport
• Network
• Data link
• Physical
Protocol: it’s an agreement of request and services between two or more entities.
802.3 Ethernet
803.4 token bus
803.5 token ring
Congestion: when load is more than the resources can handle.
Topologies:
• Bus
• Star
• Ring
• Mesh
Kerberos: its an authentication service by MIT
Gateway: relay packet among networks that have different protocols
Router: relay packets between LAN’s of different topology.
Repeater: used to amplify signals.
Bridge: to divide large network into smaller segments.
TCP/IP (transfer control protocol/ internet protocol)
• Application
• Transport
• Internet
• Network
Profile of the Company
Patni Computer Systems (PCS) is international software and applications outsourcing
specialist, with over 28 years of experience. Founded in 1978, PCS now offers a wide range of
services, including application development / maintenance, ERP implementation & related
services, E-Commerce & Web enabling solutions, Euro conversion, staff augmentation and
offshore development.
PCS primary development facilities in Mumbai, Navi Mumbai, Pune, Gandhinagar, Chennai
and NOIDA (India).
PCS provides services to a varied field including Airlines, Automotive, Financial Services,
Electronics, Healthcare, Hospitality, Manufacturing, Products, and Utilities.
Few General questions you can think over
Quick way of multiplying a number by 7. n<<3 - n = 7n
Just In Time Concept :Elimination of waste by purchasing manufacturing exactly when needed
Semaphore: A method synchronization of multiple processes
idle thread: The special thread a dispatcher will execute when no ready thread is found.
(Try, only if you are 100% thorough with the above-mentioned material)
what is xml
importance of accounts in your curriculum
virtual functions
explain ip address
similarity between dbms and os
differentiate between c and c++
use of ::(scope resolution operator)
what is testing
types of testing
difference between black box and white box
what is a page fault
what is fragmentation
types of indexing
TIPS:
• For PCS the most important thing is your familiarity with technical terms and the
standard of the definition you provide. So, please try to learn above definitions as it is.
• It wont matter even if you are not able to answer any technical question but then don’t
loose your calm at any stage.
• Be prepared for HR questions as well like about yourself, strengths, weakness, hobby,
last movie you have seen, etc.
• Be very thorough with the profile of company.
• Excerpts (verbatim )from the response/feedback of students about technical interview
of PCS, try to think on these lines: its combination of both tech/personal , be prepare
with your final year project , prepare with basic question , hobby , unpredictable , c
prog to reverse a string , Profile , TECHNICAL JARGONS , Strengths/ weaknesses,
career goals , current affairs , brushing up of important topics.