Synechron Technologies Pvt Ltd interview questions and answers https://www.wikitechy.com/interview-questions/tag/synechron-technologies-pvt-ltd-interview-questions-and-answers/ Interview Questions Fri, 17 Sep 2021 10:27:05 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 https://www.wikitechy.com/interview-questions/wp-content/uploads/2025/10/cropped-wikitechy-icon-32x32.png Synechron Technologies Pvt Ltd interview questions and answers https://www.wikitechy.com/interview-questions/tag/synechron-technologies-pvt-ltd-interview-questions-and-answers/ 32 32 What is the error message that you would get if you try to assign “Null” to an integer variable ? https://www.wikitechy.com/interview-questions/visual-basic/what-is-the-error-message-that-you-would-get-if-you-try-to-assign-null-to-an-integer-variable/ https://www.wikitechy.com/interview-questions/visual-basic/what-is-the-error-message-that-you-would-get-if-you-try-to-assign-null-to-an-integer-variable/#respond Thu, 22 Jul 2021 07:48:17 +0000 https://www.wikitechy.com/interview-questions/?p=1216

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.
]]> https://www.wikitechy.com/interview-questions/visual-basic/what-is-the-error-message-that-you-would-get-if-you-try-to-assign-null-to-an-integer-variable/feed/ 0 What is the difference between Power BI Pro and free Power BI Service ? https://www.wikitechy.com/interview-questions/power-bi/what-is-the-difference-between-power-bi-pro-and-free-power-bi-service/ https://www.wikitechy.com/interview-questions/power-bi/what-is-the-difference-between-power-bi-pro-and-free-power-bi-service/#respond Wed, 21 Jul 2021 14:22:43 +0000 https://www.wikitechy.com/interview-questions/?p=1162

Difference between Power BI Pro and free Power BI Service

Power BI Pro
Free Power BI Service
Power BI Pro allows you to use live data sources,
on premise data and allows to join with group
using Office 365 groups.		 BY free Power BI Service and the Power BI Desktop, you can only analyze and visualize data but does not share or assist with our team.
Power BI Free vs Pro
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-the-difference-between-power-bi-pro-and-free-power-bi-service/feed/ 0 What is the Foundational elements of Power BI ? https://www.wikitechy.com/interview-questions/power-bi/what-is-the-foundational-elements-of-power-bi/ https://www.wikitechy.com/interview-questions/power-bi/what-is-the-foundational-elements-of-power-bi/#respond Wed, 21 Jul 2021 14:21:53 +0000 https://www.wikitechy.com/interview-questions/?p=1161

Foundational elements of Power BI

  • Strong project management skills.
  • Good Communication.
  • SQL is easy to learn a most of analytics skills.
  • Decent grasp Python-Pandas or R to do data crunching and manipulation.
  • Based on Good visualization skills (start by checking out CSS color palettes).
  • The Tableau or Power BI come at the very end of the analytics pipeline, it’s good you have an overall grasp.
Foundatinal Element
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-the-foundational-elements-of-power-bi/feed/ 0 What is the level of data security provided by Power BI ? https://www.wikitechy.com/interview-questions/power-bi/what-is-the-level-of-data-security-provided-by-power-bi/ https://www.wikitechy.com/interview-questions/power-bi/what-is-the-level-of-data-security-provided-by-power-bi/#respond Wed, 21 Jul 2021 14:19:39 +0000 https://www.wikitechy.com/interview-questions/?p=1160

Level of Data Security provided by Power BI

  • Power BI stores all the uploaded data into Azure BLOB and Azure SQL Database.
  • Both databases are only accessible by an Admin user, which means that end-users cannot access the database, eliminating user-level security.
  • Now this data is on the Microsoft cloud and when it comes to their security, there isn’t much to explain except to say that the data is 100% secured.
Data security provided by Power BI
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-the-level-of-data-security-provided-by-power-bi/feed/ 0 What is the way to use of Power BI ? https://www.wikitechy.com/interview-questions/power-bi/what-is-the-way-to-use-of-power-bi/ https://www.wikitechy.com/interview-questions/power-bi/what-is-the-way-to-use-of-power-bi/#respond Wed, 21 Jul 2021 14:17:43 +0000 https://www.wikitechy.com/interview-questions/?p=1159

Diffent way to use of Power BI

There are two way to use of Power BI,

    • Power BI Service
    • Power BI Desktop
power bi function

Power BI Service:

  • Cloud SaaS is called the Power BI service for accessing the cloud service.
power bi component

Power BI Desktop:

  • Power BI Desktop was an free application that works in joining together with the Power BI Service.
  • Power Bi Desktop allows you to do the following.
    • Get the data from collection of unlike sources.
    • Create relationships between your data and to end with fine or desirable qualities of your data model.
    • Then Create and save your reports.
    • And Upload or publish your reports.
  • The reports created using Power BI Desktop then published in Power BI Service right from the Power BI Desktop application.
  • Using both Power BI Service and Power BI Desktop the cost is free.
what is powerbi
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-the-way-to-use-of-power-bi/feed/ 0 What is the disadvantages of Power BI ? https://www.wikitechy.com/interview-questions/power-bi/what-is-the-disadvantages-of-power-bi/ https://www.wikitechy.com/interview-questions/power-bi/what-is-the-disadvantages-of-power-bi/#respond Wed, 21 Jul 2021 14:15:47 +0000 https://www.wikitechy.com/interview-questions/?p=1158

Disadvantages of Power BI

  • Power BI will not accept files larger than 1GB.
  • Power BI reports and dashboards cannot accept or pass user, account or other entity parameters.
  • This makes it impossible to create entity specific dashboards such as a dashboard for an account, opportunity, case, or campaign.
  • Very few data sources that permit real-time connections to Power BI reports and dashboard.
  • Users have the same email domains listed with your office 365 tenant can only be shared dashboards and reports.
  • The integration to Dynamics CRM is limited.
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-the-disadvantages-of-power-bi/feed/ 0 What is the advantages of Power BI ? https://www.wikitechy.com/interview-questions/power-bi/what-is-the-advantages-of-power-bi/ https://www.wikitechy.com/interview-questions/power-bi/what-is-the-advantages-of-power-bi/#respond Wed, 21 Jul 2021 14:14:55 +0000 https://www.wikitechy.com/interview-questions/?p=1157

Advantages of Power BI

  • Minimal upfront costs.
  • View Power BI reports across multiple platforms and devices.
  • Consolidate multiple data sources through Power BI.
  • Instantly share dashboards.Like
    • Spark
    • Hadoop
    • Google Analytics
    • SAP
    • Salesforce
    • MailChimp
  • Drag-and-drop functionality.
  • Drill-down functionality.
  • Schedule Data Refresh.
  • Write simple sentences to run report queries.
Advantages of Power Bi
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-the-advantages-of-power-bi/feed/ 0 What is the Key features of Power BI ? https://www.wikitechy.com/interview-questions/power-bi/what-is-the-key-features-of-power-bi/ https://www.wikitechy.com/interview-questions/power-bi/what-is-the-key-features-of-power-bi/#respond Wed, 21 Jul 2021 14:12:44 +0000 https://www.wikitechy.com/interview-questions/?p=1156

Key features of PowerBi

  • Hybrid deployment support
  • Quick Insights
  • Cortana integration
  • Customization
  • APIs for integration

Hybrid deployment support:

  • It has implements built-in connectors that allow Power BI tools to connect with a many different data sources from Microsoft, Salesforce and other vendors.

Quick Insights:

  • It allows us to create subsets of data and it automatically apply analytics for data.
Key features of power bi

Learn Power BI – Power BI tutorial – Key features of Power BI – Power BI examples – Power BI programs

Cortana integration:

  • It is especially popular on mobile devices, allows us to verbally query data and access results.

Customization:

  • It allows developers to change the appearance of default visualization and reporting tools and import new tools into the platform.

APIs for integration:

  • It gives developers with Application programming interface(APIs) and sample code for integrating the Power BI dashboard into various software outcome.
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-the-key-features-of-power-bi/feed/ 0 What is Power BI ? https://www.wikitechy.com/interview-questions/power-bi/what-is-power-bi/ https://www.wikitechy.com/interview-questions/power-bi/what-is-power-bi/#respond Wed, 21 Jul 2021 14:10:52 +0000 https://www.wikitechy.com/interview-questions/?p=1155

Power BI

what is power bi

Learn Power BI – Power BI tutorial – Power BI – Power BI examples – Power BI programs

  • Power BI is a group of software applications, services and connectors.
  • It combined work to change separate fields of data into visually absorp, logical and interconnected intuition.
  • Whatever your data was a simple Excel spreadsheet or a group of cloud-based and on-premises combined data warehouses.
powerbi tutorial

Learn Power BI – Power BI tutorial – Power BI – Power BI examples – Power BI programs

  • It permits to easily connect your data sources, visualize and share what you want to anyone or everyone.
  • By using Power BI as it automatically extracts data from all sources and brings that to a unified viewing pane and can analyze and visualize data, cooperate with our team to build reports and share the reports with people have plan.
power bi
]]> https://www.wikitechy.com/interview-questions/power-bi/what-is-power-bi/feed/ 0 Difference between Procedure and Function ? https://www.wikitechy.com/interview-questions/oracle/difference-between-procedure-and-function/ https://www.wikitechy.com/interview-questions/oracle/difference-between-procedure-and-function/#respond Tue, 20 Jul 2021 09:28:09 +0000 https://www.wikitechy.com/interview-questions/?p=1135

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

CREATE [OR REPLACE] PROCEDURE procedure_name (<Argument> {IN, OUT, IN OUT}    <Datatype>,…)  
IS 
  Declaration section<variable, constant> ; 
BEGIN 
  Execution section 
EXCEPTION 
  Exception section  
END

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

CREATE [OR REPLACE] FUNCTION function_name [parameters]  
 RETURN return_datatype;  {IS, AS} 
 Declaration_section <variable,constant> ;
 BEGIN   
    Execution_section 
    Return return_variable;   
 EXCEPTION 
   exception section   
    Return return_variable;  
 END;

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.
]]> https://www.wikitechy.com/interview-questions/oracle/difference-between-procedure-and-function/feed/ 0 What is the maximum size of a row in oracle 9i ? https://www.wikitechy.com/interview-questions/oracle/what-is-the-maximum-size-of-a-row-in-oracle-9i/ https://www.wikitechy.com/interview-questions/oracle/what-is-the-maximum-size-of-a-row-in-oracle-9i/#respond Tue, 20 Jul 2021 09:27:14 +0000 https://www.wikitechy.com/interview-questions/?p=1134

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.
]]> https://www.wikitechy.com/interview-questions/oracle/what-is-the-maximum-size-of-a-row-in-oracle-9i/feed/ 0 What is Joomla ? https://www.wikitechy.com/interview-questions/joomla/what-is-joomla/ https://www.wikitechy.com/interview-questions/joomla/what-is-joomla/#respond Mon, 19 Jul 2021 14:55:01 +0000 https://www.wikitechy.com/interview-questions/?p=1057

What is Joomla ?

  • Joomla is a free and open-source Content Management System (CMS) for distributing web content.
  • It is built on a Model-View-Controller (MVC) web application framework that can be used individually, and the CMS that allows to build powerful online applications.
  • Joomla is one of the most popular website software’s.
  • Joomla is an independent platform, user friendly, extendable, multilingual, accessible, responsive, search engine optimized and so much more.

What is Content Management System (CMS) ?

  • CMS is an application (web-based), that provides capabilities for multiple users with different permission levels to manage (all or a section of) content, data or information of a website project, or intranet application.
  • Managing content refers to creating, editing, archiving, publishing, collaborating on, reporting, distributing website content, data and information.

Uses of Joomla

  • Joomla is used to whole world and millions of websites of all shapes and sizes. Joomla can be used for,
    • Corporate websites or portals, intranets and extranets.
    • Small business websites.
    • Online magazines, newspapers, and publications.
    • E-commerce and online reservations.
    • Government, non-profit and organizational websites.
    • Community-based, school and church websites or portals.
    • Personal or family homepages.
What is Joomla
]]> https://www.wikitechy.com/interview-questions/joomla/what-is-joomla/feed/ 0 What are the differences between Impala and Apache Drill ? https://www.wikitechy.com/interview-questions/cloudera-impala/what-are-the-differences-between-impala-and-apache-drill/ https://www.wikitechy.com/interview-questions/cloudera-impala/what-are-the-differences-between-impala-and-apache-drill/#respond Mon, 19 Jul 2021 06:41:05 +0000 https://www.wikitechy.com/interview-questions/?p=1025

Difference between Impala and Apache Drill

Index Cloudera impala Apache Drill
Description Analytic DBMS for Hadoop Schema-free SQL Query Engine for Hadoop,
NoSQL and Cloud Storage
Primary database modele relational DBMS document store relational DBMS
Developer Cloudera Apache Software Foundation
License open source open source
Server operating systems Linux Linux,OSX, Windows
Data scheme yes schema-free
Secondary indexes yes no
SQL SQL-like DML and DDL statements SQL SELECT statement is SQL:2003 compliant
Supported programming languages All languages supporting JDBC/ODBC C++
cloudera-impala-tutorials
Query planner
ximpala arch
]]> https://www.wikitechy.com/interview-questions/cloudera-impala/what-are-the-differences-between-impala-and-apache-drill/feed/ 0 What is the difference between Impala and Apache Hive ? https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-difference-between-impala-and-apache-hive/ https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-difference-between-impala-and-apache-hive/#respond Mon, 19 Jul 2021 06:40:04 +0000 https://www.wikitechy.com/interview-questions/?p=1024

Difference between Impala and Apache Hive

Impala Apache hive
Impala does runtime code generations
for “big loops ” using llvm.		 Apache hive generates query
expressions at compile time.
Hadoop 2.6.0 Hadoop 2.7.3
Runtime Filtering Optimization Enabled All queries run through LLAP
Parquet format with snappy compression ORCFile format with zlib compression
Impala avoids startup overhead
as daemon processes are started at boot
time itself, always being ready to processes a query.		 Every hive query has this problem
of “cold start”.
Impala is meant for interactive computing. Apache Hive might not be ideal
for interactive computing .
Impala is more like MPP database. Hive is batch based Hadoop MapReduce .
Impala does not support complex types. Hive supports complex types .
Impala does not support fault tolerance Apache Hive is fault tolerant
hive-architecture

rimpala
]]> https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-difference-between-impala-and-apache-hive/feed/ 0 What is the difference between Apache Hadoop and Cloudera in big data ? https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-difference-between-apache-hadoop-and-cloudera-in-big-data/ https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-difference-between-apache-hadoop-and-cloudera-in-big-data/#respond Mon, 19 Jul 2021 06:38:24 +0000 https://www.wikitechy.com/interview-questions/?p=1023

Difference between Apache Hadoop and Cloudera in big data

  • Apache Hadoop is the Hadoop distribution from Apache group.
  • Cloudera Hadoop has its own supply of Hadoop which is designed on top of Apache Hadoop. so it does not have latest release of Hadoop.
  • Cloudera Hadoop contains extra tools. while Hadoop distributions like Cloudera Search, Impala, Cloudera Navigator and Cloudera Manager these are not involved in Cloudera Hadoop.
  • These additional tools turns out Cloudera Hadoop to be slightly open source and proprietary.
Distribution hadoop
  • Apache Hadoop is very important to use to cope up with any data, no matter how large or what type or complex it is. It works like a fluid way or can say it is very faster, cheaper and reliable analytic tool than others.
  • Even, it can easily work on unstructured, and schemaless data and people can easily ground their data into a format without reformating or putting any other efforts.
  • Apart from this, via Apache Hadoop various programming model has been simplified to allow you to quickly write and test the software in distributed systems.
  • This is an open-source Apache Hadoop distribution usually, focus on enterprise-class deployments.
  • Cloudera Inc is a very popular American software company, known for providing Apache Hadoop-based software, services, and full support for the same.
  • With Cloudera, it is said that Hadoop is just a starting to create your data management strategy, and you can easily use the same to add the security and other various functions to create an enterprise-grade foundation for your data.
]]> https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-difference-between-apache-hadoop-and-cloudera-in-big-data/feed/ 0 What is the architectural design and features of Cloudera Impala ? https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-architectural-design-and-features-of-cloudera-impala/ https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-architectural-design-and-features-of-cloudera-impala/#respond Mon, 19 Jul 2021 06:35:32 +0000 https://www.wikitechy.com/interview-questions/?p=1022

Components of the Impala Server

cloudera-impala-tutorials
  • The impala server consist of distributed and massively parallel processing info engine.
  • It run on particular hosts among your CDH cluster with a various daemon processes.
The Impala Daemon
  • The core impala element may be a daemon method that runs on every node of the cluster, and its physically described by the impalad method.
  • Then read and write a informative files; which accepts questions transmitted from the impala-shell command, Hue, JDBC, or ODBC; parallelizes the questions can seperate work to alternative nodes within the impala cluster; and transmits intermediate question results back to the central organizer node.
  • The impala daemon running on any node, and that node is the organizer node for that question when You can submit a question.
  • The other nodes transmit partial results back to the organizer, that constructs the ultimate result set for a question.
  • You may continuously connect with a similar impala daemon for convenience.When running experiments with possibility through the impala-shell command.
  • For clusters running production workloads, you would possibly load-balance between the nodes by submitting every question to a distinct impala daemon in round-robin vogue, exploitation the JDBC or ODBC interfaces.
  • Its verify that nodes and may settle for new work. Through the impala daemons are in constant communication with the statestore.

The Impala Statestore

  • The impala element called the statestore checks on the health of impala daemons on all the nodes during a cluster, and unendingly relays its findings to every of these daemons.
  • It is physically described by a daemon method named statestored; you simply would like such a method on one node within the cluster.
  • If an impala node goes offline because of hardware failure, network error, software package issue, or alternative reason, the statestore informs all the opposite nodes so future queries will avoid creating requests to the unreached node.
architectural design

New options in Impala:

  • Performance and quantifiability enhancements.
  • Integration with Apache koodoo.
  • Security.
  • The REFRESH statement currently updates data regarding HDFS block locations.
  • [IMPALA-1654] many varieties of DDL operations will currently work on a spread of partitions.
]]> https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-the-architectural-design-and-features-of-cloudera-impala/feed/ 0 What is Cloudera’s technology stack ? https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-clouderas-technology-stack/ https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-clouderas-technology-stack/#respond Mon, 19 Jul 2021 06:33:22 +0000 https://www.wikitechy.com/interview-questions/?p=1021

Cloudera’s technology stack

  • Here are some products that make up Cloudera’s tech stack:
    • Adobe Experience Manager,
    • Amazon EC2,
    • Apache (Ant, HBase, Kafka, Maven, Mesos, Solr, Spark, Web Server),
    • Atlassian JIRA,
    • Bugsnag,
    • C++,
    • Cask Data Applicaiton Platform,
    • Dyn DNS,
    • Fastly,
    • Git,
    • GitHub,
    • Google Fonts,
    • Impala,
    • Java,
    • Jenkins,
    • Mirantis,
    • Piston,
    • Python,
    • RBCommons,
    • Red Hat Enterprise Linux,
    • Scala, and
    • VMware vSphere.

Additionally, here’s a list of other software products that Cloudera is using internally,

  • Marketing: AdRoll, AppNexus, BrightFunnel, Demandbase
  • Sales and Support: Infer, MindTickle, Outreach, Salesforce Sales Cloud
  • Analytics: Adobe Analytics, Amplitude, Chartbeat, Tableau Software
  • HR: AngelList Jobs, Codility, RolePoint, The Muse
  • Finance: Concur, Ombud, SteelBrick
  • Productivity: Box, Google Apps for Work, LibreOffice, Microsoft Office 365
Cloudera enterprise
]]> https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-clouderas-technology-stack/feed/ 0 What is cloudera impala ? https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-cloudera-impala/ https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-cloudera-impala/#respond Mon, 19 Jul 2021 06:30:25 +0000 https://www.wikitechy.com/interview-questions/?p=1015

Cloudera’s Impala

cloudera-impala-tutorial
Impala was the first to bring SQL querying to the public in April 2013. Impala comes with a bunch of interesting features:
  • Impala can query many file format such as Parquet, Avro, Text, RCFile, SequenceFile
  • Impala supports data stored in HDFS, Apache HBase and Amazon S3
  • Impala supports multiple compression codecs:
    • Snappy (Recommended for its effective balance between compression ratio and decompression speed),
    • Gzip (Recommended when achieving the highest level of compression),
    • Deflate (not supported for text files), Bzip2, LZO (for text files only);
  • Impala provides security through authorization based on Sentry (OS user ID)
    • Defining which users are allowed to access which resources,
    • What operations are they allowed to perform authentication based on Kerberos + ability to specify Active Directory username/password,
    • How does Impala verify the identity of the users to confirm that they are allowed exercise their privileges assigned to that user auditing,
    • What operations were attempted,
    • Did they succeed or not, allowing to track down suspicious activity; audit data are collected by Cloudera Manager;
  • Impala supports SSL network encryption between Impala and client programs, and between the Impala-related daemons running on different nodes in the cluster;
  • Impala allows to use UDFs and UDAFs;
  • Impala orders the joins automatically to be the most efficient;
  • Impala allows admission control – prioritization and queueing of queries within impala;
  • Impala allows multi-user concurrent queries;
  • Impala caches frequently accessed data in memory;
  • Impala computes statistics (with COMPUTE STATS);
  • Impala provides window functions (aggregation OVER PARTITION, RANK, LEAD, LAG, NTILE, and so on) – to provide more advanced SQL analytic capabilities (since version 2.0);
  • Impala allows external joins and aggregation using disk (since version 2.0) – enables operations to spill to disk if their internal state exceeds the aggregate memory size;
  • Impala allows subqueries inside WHERE clauses;
  • Impala allows incremental statistics – only run statistics on the new or changed data for even faster statistics computations;
  • Impala enables queries on complex nested structures including maps, structs and arrays;
  • Impala enables merging (MERGE) in updates into existing tables;
  • Impala enables some OLAP functions (ROLLUP, CUBE, GROUPING SET);
  • Impala allows use of impala for inserts and updates into HBase.
]]> https://www.wikitechy.com/interview-questions/cloudera-impala/what-is-cloudera-impala/feed/ 0 What is the difference between primary, partition and clustering key in Cassandra ? https://www.wikitechy.com/interview-questions/cassandra/what-is-the-difference-between-primary-partition-and-clustering-key-in-cassandra/ https://www.wikitechy.com/interview-questions/cassandra/what-is-the-difference-between-primary-partition-and-clustering-key-in-cassandra/#respond Tue, 13 Jul 2021 05:53:14 +0000 https://www.wikitechy.com/interview-questions/?p=446

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.
cassandra cluster

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.
reate keyspace Students_Details with replication = {‘class’ : ‘SimpleStrategy’, ‘replication_factor’:1};
  • Now switch to the students_details keyspace:
use students_details;
  • Check the number of tables present in the keyspace:
students_details> desc TABLES;
  • We will create a table, student , that contains general information about any student.
create table student (stuid int, avg_marks float, description text, 
                      primary key (stuid));
  • Type the following insert statements to enter some data into this table.
insert into student (stuid, avg_marks, description) values (1,25.5,’student 1′);
insert into student (stuid, avg_marks, description) values (2,35.5,’student 2′);
  • To view the details just inserted.
students_details> select * from student;
]]> https://www.wikitechy.com/interview-questions/cassandra/what-is-the-difference-between-primary-partition-and-clustering-key-in-cassandra/feed/ 0 What is the difference between Cassandra and Hadoop ? https://www.wikitechy.com/interview-questions/cassandra/what-is-the-difference-between-cassandra-and-hadoop/ https://www.wikitechy.com/interview-questions/cassandra/what-is-the-difference-between-cassandra-and-hadoop/#respond Tue, 13 Jul 2021 05:44:49 +0000 https://www.wikitechy.com/interview-questions/?p=444
difference between cassandra and hadoop

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
]]> https://www.wikitechy.com/interview-questions/cassandra/what-is-the-difference-between-cassandra-and-hadoop/feed/ 0