Conduent interview questions and answers - Interview Questions

What is the error message that you would get if you try to assign “Null” to an integer variable ?

Editor — Thu, 22 Jul 2021 07:48:17 +0000

What is the error message that you would get if you try to assign “Null” to an integer variable ?

Error message : Cannot convert null to int because it is a non-nullable value type(or) INVALID use of NULL.

What is the difference between shell script and perl ?

Editor — Thu, 22 Jul 2021 04:09:14 +0000

What is the difference between shell script and perl ?

Shell Script	Perl
Shell script is a dependent platform only for Unix OS.	Perl is OS independent.
Shell script is a scripting language.	Perl is a programming language.
Scripting language need not be compliled.	Perl compiles the program before executing the script.
Shell Scripting using one or more built-in scripting languages.	Perl using only one scripting language.

Difference between Procedure and Function ?

Editor — Tue, 20 Jul 2021 09:28:09 +0000

Difference between Procedure and Function ?

Procedure

A procedure is a named PL/SQL block which performs one or more specific task.This is similar to a procedure in other programming languages.
A procedure has a header and a body.
The header consists of the name of the procedure and the parameters or variables passed to the procedure.
The body consists declaration section, execution section and exception section similar to a general PL/SQL Block. A procedure is similar to an anonymous PL/SQL Block but it is named for repeated usage.

We can pass parameters to procedures in three ways

Parameters	Description
IN type	These types of parameters are used to send values to stored procedures
OUT type	These types of parameters are used to get values from stored procedures. This is similar to a return type in functions.
IN OUT type	These types of parameters are used to send values and get values from stored procedures.

Syntax

[pastacode lang=”markdown” manual=”CREATE%20%5BOR%20REPLACE%5D%20PROCEDURE%20procedure_name%20(%3CArgument%3E%20%7BIN%2C%20OUT%2C%20IN%20OUT%7D%20%20%20%20%3CDatatype%3E%2C%E2%80%A6)%20%20%0AIS%20%0A%20%20Declaration%20section%3Cvariable%2C%20constant%3E%20%3B%20%0ABEGIN%20%0A%20%20Execution%20section%20%0AEXCEPTION%20%0A%20%20Exception%20section%20%20%0AEND” message=”” highlight=”” provider=”manual”/]

Functions

A function is a named PL/SQL Block which is similar to a procedure.
The major difference between a procedure and a function is, a function must always return a value, but a procedure may or may not return a value.

Syntax

[pastacode lang=”markdown” manual=”CREATE%20%5BOR%20REPLACE%5D%20FUNCTION%20function_name%20%5Bparameters%5D%20%20%0A%20RETURN%20return_datatype%3B%20%20%7BIS%2C%20AS%7D%20%0A%20Declaration_section%20%3Cvariable%2Cconstant%3E%20%3B%0A%20BEGIN%20%20%20%0A%20%20%20%20Execution_section%20%0A%20%20%20%20Return%20return_variable%3B%20%20%20%0A%20EXCEPTION%20%0A%20%20%20exception%20section%20%20%20%0A%20%20%20%20Return%20return_variable%3B%20%20%0A%20END%3B” message=”” highlight=”” provider=”manual”/]

Procedure vs function

Procedure	Function
Used mainly to a execute certain process.	Used mainly to perform some calculation.
Cannot call in SELECT statement.	A Function that contains no DML statements can be called in SELECT statement.
Use OUT parameter to return the value.	Use RETURN to return the value.
It is not mandatory to return the value.	It is mandatory to return the value.
RETURN will simply exit the control from subprogram.	RETURN will exit the control from subprogram and also returns the value.
Return datatype will not be specified at the time of creation.	Return datatype is mandatory at the time of creation.

What is the maximum size of a row in oracle 9i ?

Editor — Tue, 20 Jul 2021 09:27:14 +0000

What is the maximum size of a row in oracle 9i ?

The oracle is Unlimited of size.There is no limitations for row size in oracle 9i.

Lazy writer in Memory ?

Editor — Sun, 18 Jul 2021 20:31:13 +0000

Lazy write

Lazy write is an effect caused by the use of a write-back cache. In a write-back cache, data is first written to the cache and then is later (during a particular time such as an idle machine cycle) is written to the disk or memory.
This type of cache is more complex to implement, due to the need to track each locations that have been written over and what needs to be marked as dirty to fix later.

Lazy writer in Memory

Lazy writer is a thread which is present for each NUMA node (and every instance has at least one) that scans through the buffer cache associated with that node.
The lazy writer thread sleeps for a specific interval of time, and when it wakes up, it examines the size of the free buffer list.
If the list is below a certain threshold, which depends on the total size of the buffer pool, the lazy writer thread scans the buffer pool to repopulate the free list.
As buffers are added to the free list, they are also written to disk if they are dirty.
So if there is no memory pressure and memory notification is stable it sleeps
The sole purpose of Lazy Writer is to maintain some free buffers in the SQL Server Buffer Pool.
Lazy writer runs periodically and check which buffers can be flushed and returned to the free pool.
So even SQL Server is not under memory pressure, it will also work regularly.

What is the difference between the SubQuery and Corelated SubQuery ?

Editor — Sun, 18 Jul 2021 20:30:02 +0000

Subquery

The inner query is executed only once.
The inner query will get executed first and the output of the inner query used by the outer query.
The inner query is not dependent on outer query.

SELECT Employee_name, dept_no 
FROM Employee 
WHERE Employee_name IN (SELECT Employee_name FROM Customer);

Correlated SubQuery

The outer query will get executed first and for every row of outer query, inner query will get executed.
So the inner query will get executed as many times as number of rows in result of the outer query.
The outer query output can use the inner query output for comparison. This means inner query and outer query dependent on each other.

[pastacode lang=”sql” manual=”SELECT%20Employee_name%2Cdept_id%20%0AFROM%20Employee%0AWHERE%20Employee_name%20IN%20(SELECT%20Employee_name%20FROM%20dept%20WHERE%20Employee.dept_id%3Ddept.dept_id)%3B” message=”” highlight=”” provider=”manual”/]

What is the Difference between join and union ?

Editor — Sun, 18 Jul 2021 20:27:46 +0000

Union

- The union operator combines the results of two or more queries into a single result set. But no.of columns must match in both/all the queries (and also the order) which are used for union.
- We can union two tables irrespective of common field.
- The UNION set operator is used for combining data from two tables which have columns with the same datatype.
  - Union – Returns with no duplicate rows.
  - Union all – Retruns with duplicate rows (No. of rows returned = No. of rows in Query1 + No. of rows in Query 2).

We cannot use the union operator within a create view statement.
We cannot use the union operator on text and image columns.

Syntax

[pastacode lang=”sql” manual=”SELECT%20expression1%2C%20expression2%2C%20…%20expression_n%0AFROM%20tables%0A%5BWHERE%20conditions%5D%0AUNION%0ASELECT%20expression1%2C%20expression2%2C%20…%20expression_n%0AFROM%20tables%0A%5BWHERE%20conditions%5D%3B” message=”” highlight=”” provider=”manual”/]

Join

Joins are used to extract information from more than one table based on the related column/coloums (PK and RFK) any no. of rows can be retrived based on matching colums.
We can join two tables by ‘join’ if they have common field.
A Join is used for displaying columns with the same or different names from different tables.
Different types of joins are Inner join=equi join=join , outer join (Right outer join/right join, Left outer join / left join), Cross join , and full outer join/outer join.
We can use join operator within a create view statement.
We can use the join operator on text and image columns.

Syntax

[pastacode lang=”sql” manual=”SELECT%20column-names%0AFROM%20table-name1%20JOIN%20table-name2%20%0AON%20column-name1%20%3D%20column-name2%0AWHERE%20condition” message=”” highlight=”” provider=”manual”/]

What is the SQLCode -501 ?

Editor — Sun, 18 Jul 2021 20:24:32 +0000

What is the SQLcode -501 ?

SQLcode -501 pops up to show that , the Cursor identified in fetch or close statement is not opened.

SQL error code means it return codes that are preceded by a minus sign (-) indicate that the SQL statement execution was unsuccessful.
- If SQLCODE = 0, execution was successful.
- If SQLCODE > 0, execution was successful with a warning.
- If SQLCODE < 0, execution was not successful.
- SQLCODE = 100, “no data” was found.

What is the difference between a HAVING CLAUSE and a WHERE CLAUSE ?

Editor — Sun, 18 Jul 2021 20:21:49 +0000

Where Clause	Having Clause
WHERE clause can be used with – Select, Insert, and Update statements.	HAVING clause can only be used with the Select statement.
The WHERE search condition is applied before the grouping operation occurs.	The HAVING search condition is applied after the grouping operation occurs.
Aggregate functions cannot be used in the WHERE clause, unless it is in a sub query contained in a HAVING clause.	Aggregate functions can be used in Having clause.

Example of WHERE and HAVING clause

We have two tables Wikitechy_Employee and Department. Wikitechy_Employee contains details of employees e.g. id, name, age, salary and department id, while Department contains id and department name.
In order to show, which employee works for which department we need to join two tables on DEPT_ID to get the the department name.
Our requirement is to find how many employees are working in each department and average salary of department.
In order to use WHERE clause, we will only include employees who are earning more than 5000.
Before executing our query which contains WHERE, HAVING, and GROUP BY clause, let see data from Wikitechy_Employee and Department table:

SELECT * FROM Wikitechy_Employee;

EMP_ID	EMP_NAME	EMP_AGE	EMP_SALARY	DEPT_ID
1	George Orwell	23	10000	1
2	J.K. Rowling	24	7000	2
3	Kurt Vonnegut	25	8000	3
4	Virginia Woolf	27	6000	1
5	Ernest Hemingway	28	5000	2

SELECT * FROM Department;

DEPT_ID	DEPT_NAME
1	Accounting
2	Marketing
3	Sales

Sample Code

[pastacode lang=”sql” manual=”SELECT%20d.DEPT_NAME%2C%0Acount(e.EMP_NAME)%20as%20NUM_EMPLOYEE%2C%20%0Aavg(e.EMP_SALARY)%20as%20AVG_SALARY%20FROM%20Employee%20e%2C%0ADepartment%20d%20WHERE%20e.DEPT_ID%3Dd.DEPT_ID%20AND%20EMP_SALARY%20%3E%205000%20GROUP%20BY%20d.DEPT_NAME%3B” message=”” highlight=”” provider=”manual”/]

Output

DEPT_NAME	NUM_EMPLOYEE AVG_SALARY	AVG_SALARY
Accounting	1	8000
Marketing	1	7000
Sales	2	8000

From the number of employee (NUM_EMPLOYEE) column you can see that only Vijay who work for Marketing department is not included in result set because his earning 5000.
This example shows that, condition in WHERE clause is used to filter rows before you aggregate them and then HAVING clause comes in picture for final filtering, which is clear from following query, now Marketing department is excluded because it doesn’t pass condition in HAVING clause i..e AVG_SALARY > 7000

Sample Code

[pastacode lang=”sql” manual=”SELECT%20d.DEPT_NAME%2C%0Acount(e.EMP_NAME)%20as%20NUM_EMPLOYEE%2C%0Aavg(e.EMP_SALARY)%20as%20AVG_SALARY%20FROM%20Employee%20e%2C%0ADepartment%20d%20WHERE%20e.DEPT_ID%3Dd.DEPT_ID%20AND%20EMP_SALARY%20%3E%205000%20GROUP%20BY%20d.DEPT_NAMEHAVING%20AVG_SALARY%20%3E%207000%3B” message=”” highlight=”” provider=”manual”/]

Output

DEPT_NAME	NUM_EMPLOYEE	AVG_SALARY
Accounting	1	8000
Sales	2	8000

Difference between Clustered and Non-clustered index ?

Editor — Sun, 18 Jul 2021 20:18:58 +0000

Difference between Clustered and Non-clustered index ?

Clustered Index	Non-clustered Index
Clustered index will be created by default when you create primary key on a column. So we can create one clustered index per table.	Non clustered index will be created automatically when you create unique key on a column. A table can have no.of unique keys, so we can create no.of non-clustered indexes per table.
The Leaf Level of a clustered index is the actual data page.	The Leaf Level of a non-clustered index does not consist of the actual data page.
Only one clustered index can be created.	Many non clustered index(Numbers depends on the database software) can be created.

What is an Index ?

Editor — Sun, 18 Jul 2021 20:16:01 +0000

What is an Index ?

Index is a database object which improves the efficiency of the query. When queries are run against a database, an index on that database basically helps in the way the data is sorted to process the query for faster and data retrievals are much faster when we have an index.

How to find the second highest salary from emp table ?

Editor — Sun, 18 Jul 2021 20:12:51 +0000

How to find the second highest salary from emp table ?

Select max(sal) from table_name where sal<(select max(sal)from table_name)

What is the difference between primary, partition and clustering key in Cassandra ?

Editor — Tue, 13 Jul 2021 05:53:14 +0000

Primary Key:

In Cassandra, a table contain a number of rows.
Each row is represent by a primary key, also called the row key.
There are a number of columns in a row but the number of columns can vary in different rows.
For example, a table contain a one row that have three columns whereas another row in the same table can have 10 columns.
It is also important to note that in Cassandra, both column names and values have binary types.
That means column names can have binary values, such as strings, timestamps, or an integer, etc.
This is different from SQL databases, where each row in a SQL table has a fixed number of columns, and column names can only be text.

Create table person (student_id int primary key, fname text, lname text, 
                     dateofbirth timestamp, email text, phone text);

Partition Key:

The use of a partition key is to determine the partition in the cluster that stores that row.
When data is read or written from the cluster, a function called Partitioned.It is used to calculate the hash value of the partition key.
This hash value is used to calculate the partition in the row.
For example, rows whose partition key values range from 1000 to 1234 may reside in node A, and rows with partition key values range from 1235 to 2000 may reside in node B.
If a row having a partition key that contain hash value is 1233 then it will be stored in node A.

Clustering Key

The use of the clustering key is to store row data in a categorize order.
The arrangement of data is based on columns, which are involved in the clustering key.
This arrangement makes it well ordered to recover data using the clustering key.

Example: school system

To make these concepts clear, we will consider to Create a key space with replication strategy ‘SimpleStrategy’ and replication_factor 1.

[pastacode lang=”markdown” manual=”reate%20keyspace%20Students_Details%20with%20replication%20%3D%20%7B%E2%80%98class%E2%80%99%20%3A%20%E2%80%98SimpleStrategy%E2%80%99%2C%20%E2%80%98replication_factor%E2%80%99%3A1%7D%3B” message=”” highlight=”” provider=”manual”/]

Now switch to the students_details keyspace:

[pastacode lang=”markdown” manual=”use%20students_details%3B” message=”” highlight=”” provider=”manual”/]

Check the number of tables present in the keyspace:

[pastacode lang=”markdown” manual=”students_details%3E%20desc%20TABLES%3B” message=”” highlight=”” provider=”manual”/]

We will create a table, student , that contains general information about any student.

[pastacode lang=”markdown” manual=”create%20table%20student%20(stuid%20int%2C%20avg_marks%20float%2C%20description%20text%2C%20%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20primary%20key%20(stuid))%3B” message=”” highlight=”” provider=”manual”/]

Type the following insert statements to enter some data into this table.

[pastacode lang=”markdown” manual=”insert%20into%20student%20(stuid%2C%20avg_marks%2C%20description)%20values%20(1%2C25.5%2C%E2%80%99student%201%E2%80%B2)%3B%0Ainsert%20into%20student%20(stuid%2C%20avg_marks%2C%20description)%20values%20(2%2C35.5%2C%E2%80%99student%202%E2%80%B2)%3B” message=”” highlight=”” provider=”manual”/]

To view the details just inserted.

[pastacode lang=”markdown” manual=”students_details%3E%20select%20*%20from%20student%3B” message=”” highlight=”” provider=”manual”/]

What is the difference between Cassandra and Hadoop ?

Editor — Tue, 13 Jul 2021 05:44:49 +0000

Difference between Cassandra and Hadoop:

Parameters	Cassandra	Hadoop
CAP theorem	AP	CP
Architecture	All nodes are same in Peer-to-Peer Distributed architecture.	Master/Slave. Name Node act as Master and data node act as worker node.
Read and Write Design	Read and write anywhere model.	Write once read many access models.
Area of utilization	Real time online transactional processing	Batch-oriented analytical solutions.
Mode of accessing data	Cassandra query language and Command line interface tools.	Map/Reduce for read/write operations.
Data storage model	Keys space column family to store the data and introduces primary and secondary indexes for high availability of data	File system. Large files are destroyed into small piece and copy on many data node
Fault tolerance	High availability- NO SPOF cluster all nodes are same and experienced to handle the access	when master node is down if the Single point of failure Vulnerable to be failed.
Storage schema	Combines schema from Google big table and Amazon Dynamo	Physical file system schema.
Communication	Gossip protocol	RPC/TCP and UDP

What is the virtual node in Cassandra ?

Editor — Tue, 13 Jul 2021 05:40:31 +0000

Virtual node in Cassandra:

Prior to Cassandra 1.2, every node was allocate to a particular token range.
Instead of a node being responsible for one large range of tokens, it is responsible for many smaller ranges.
In this way, one physical node is essentially hosting many smaller “virtual” nodes.
One of the new features slated for Cassandra 1.2’s release later this year is virtual nodes (vnodes.)
Vnodes:
- If you recall how token selection works currently, there’s one token per node, and a node owns exactly one contiguous range in the ring space.
Vnodes modify this paradigm from one token per node to many token per node.
Within a cluster these can be randomly selected and be non-contiguous, giving us many smaller ranges that belong to each node.

Advantages of virtual nodes

Tokens are automatically measured and allocate to every node.
when adding or removing nodes Re-balancing a cluster is automatically accomplished.
When a node merge the cluster, it assumes responsibility for an even portion of data from the other nodes in the cluster.
If a node fails, the load is develop evenly across other nodes in the cluster.
Number of vNodes can be set as node level.

What is the use of Cassandra database ?

Editor — Tue, 13 Jul 2021 05:36:30 +0000

Cassandra database:

Apache Cassandra is a high-performance provides database to manage large number of data among many commodity servers and then it is highly scalable.
It is a type of NoSQL database.
Apache Cassandra can be used for different applications.

In activity-tracking and monitoring applications:

Numerous entertainment and media organisations use Cassandra to observe user activity based on movies, music, albums, artists or other parameters.

In heavy write systems or in time-series-based applications:

Cassandra is best for heavy write systems .For example, data is logged for each request based on hits in web analytics, by type of browser, traffic sources, position, character, technology, tools, etc.

In social media analytics:

Cassandra is used by many social media providers to recognize the data and gives recommendations to their users.

In product catalogues and retail applications:

A very popular use case of Cassandra is to show fast product catalog inputs and lookup, and in retail applications.

Messaging:

Cassandra serves as the database backbone for countless mobile phone and message providers applications.

What is the use of Cassandra?

Apache Cassandra is a high-performance provides database to manage large number of data among many commodity servers and then it is highly scalable.

What is the replica placement strategy in Cassandra ?

Editor — Tue, 13 Jul 2021 05:30:15 +0000

Data replication:

Once you’ve absorbed that the strategy should fit the kind of environment you are placing your cluster in.
If you want to stay in one region of Amazon web services? You can either set yourself up as one dc per availability zone (AZ), or you can set up your cluster to use one dc and treat the AZs as racks.
Then you can replicate so that if an AZ goes down you won’t have a system problem, just some downed and unavailable servers.
If an AZ goes down (or a rack goes down) that all the copies of an important piece of data will be available.
You also are stuck with latency issues if you want to cross into a different region.
Your data has to replicate into the new region and if you went ‘simplestrategy’ you are going to have massive traffic trying to keep the database in sync.

What is the relationship between Apache Hadoop, HBase, Hive and Cassandra ?

Editor — Tue, 13 Jul 2021 05:25:21 +0000

Apache Hadoop:

It is a Big Data framework which uses Hadoop Distributed File System to Store the data and MapReduce framework to process that data. Java is used as native language to write MapReduce programs.
Apache Hbase and Cassandra are both NoSQL databases.
It does not maintain the strict ACID transactions and require better data modelling to be used effectual.
Their presentation can be calculated by benchmarking the database using a tool called YCSB(Yahoo Cloud Serving Benchmark).
Factors examine in benchmarking can be read, write ,read-modify-write latency in executing queries.

Hbase:

It is a Master -Slave NoSQL database dependent upon Hadoop cluster .
It is good for Heavy reads and less Write applications

Apache Cassandra:

It is a master less and shared-nothing, ring based architecture which does not depend upon Hadoop framework.
It is good for Write heavy and less read applications.

Apache Hive:

It is a collective processing framework to process the data using a language called Hive Query Language(HQL).
HQL is a sql wrapper on top of HDFS which protect writing Mapreduce programs in Java.
Instead one can use SQL like language to do their daily tasks.
Apache Hive is mainly used for ETL and data warehousing feature in Hadoop.
The process of hive is to create tables, joins, unions, aggregates etc. It develop visualization reports can be done by Tableau.

What is the most widely used API to write data to Cassandra ?

Editor — Tue, 13 Jul 2021 05:21:20 +0000

API to write data to Cassandra:

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In contrast, using the REST API allows the Java piece to be changed or replaced without having to re-create your input process.
Another advantage to using an API for writing is that you can queue input requests if there is a surge in usage or incoming requests to handle them as quickly as possible without message loss due to maximum connection limits or other networking issues.
NoSQL stores are now an mandatory part of any framework, the SMACK stack (Spark, Mesos, Akka, Cassandra and Kafka) is becoming well popular.
Its demonstrated scalability and its high write throughput create it the perfect partner to manage the flood of time series, IOT and industrial scale streams or financial data.
This made Apache Cassandra an clear choice as a Connect API in Kafka sink.

What is the internal architecture of the Cassandra database ?

Editor — Tue, 13 Jul 2021 05:17:52 +0000

Internal Architecture For Cassandra database:

Cassandra is build to manage big data workloads among multiple nodes with no single point of failure.
Its architecture is depend on the understanding of system and hardware failures can and do exist.
Cassandra is a row-oriented database.
Cassandra is build to manage big data.
Cassandra’s main characteristic is to store data on multiple nodes with no single point of failure.
The reason for this kind of Cassandra’s architecture was that the hardware failure can happened at any time. Any node can be down.

Cassandra is build in distributed architecture.In case of failure data stored in another node can be used.
Cassandra saves data in various nodes with a peer to peer distributed fashion framework.
All the nodes exchange information with each other using Gossip protocol.
Gossip is a protocol in Cassandra by which nodes can transfer with each other.

Conduent interview questions and answers - Interview Questions

What is the error message that you would get if you try to assign “Null” to an integer variable ?

What is the error message that you would get if you try to assign “Null” to an integer variable ?

What is the difference between shell script and perl ?

What is the difference between shell script and perl ?

Difference between Procedure and Function ?

Difference between Procedure and Function ?

Procedure

We can pass parameters to procedures in three ways

Syntax

Functions

Syntax

Procedure vs function

What is the maximum size of a row in oracle 9i ?

What is the maximum size of a row in oracle 9i ?

Lazy writer in Memory ?

Lazy write

Lazy writer in Memory

What is the difference between the SubQuery and Corelated SubQuery ?

Subquery

Correlated SubQuery

What is the Difference between join and union ?

Union

Syntax

Join

Syntax

What is the SQLCode -501 ?

What is the SQLcode -501 ?

What is the difference between a HAVING CLAUSE and a WHERE CLAUSE ?

Example of WHERE and HAVING clause

SELECT * FROM Wikitechy_Employee;

SELECT * FROM Department;

Sample Code

Output

Sample Code

Output

Difference between Clustered and Non-clustered index ?

Difference between Clustered and Non-clustered index ?

What is an Index ?

What is an Index ?

How to find the second highest salary from emp table ?

How to find the second highest salary from emp table ?

What is the difference between primary, partition and clustering key in Cassandra ?

Primary Key:

Partition Key:

Clustering Key

Example: school system

What is the difference between Cassandra and Hadoop ?

Difference between Cassandra and Hadoop:

What is the virtual node in Cassandra ?

Virtual node in Cassandra:

Advantages of virtual nodes

What is the use of Cassandra database ?

Cassandra database:

What is the use of Cassandra?

What is the replica placement strategy in Cassandra ?

Data replication:

What is the relationship between Apache Hadoop, HBase, Hive and Cassandra ?

Apache Hadoop:

Apache Cassandra:

Apache Hive:

What is the most widely used API to write data to Cassandra ?

API to write data to Cassandra:

What is the internal architecture of the Cassandra database ?

Internal Architecture For Cassandra database:

Components of Cassandra: