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SQL Interview Success: Unlocking the Top 5 Frequently Asked Queries

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 Here are the five top commonly asked SQL queries in the interviews. These you can expect in Data Analyst, or, Data Engineer interviews. Top SQL Queries for Interviews 01. Joins The commonly asked question pertains to providing two tables, determining the number of rows that will return on various join types, and the resultant. Table1 -------- id ---- 1 1 2 3 Table2 -------- id ---- 1 3 1 NULL Output ------- Inner join --------------- 5 rows will return The result will be: =============== 1  1 1   1 1   1 1    1 3    3 02. Substring and Concat Here, we need to write an SQL query to make the upper case of the first letter and the small case of the remaining letter. Table1 ------ ename ===== raJu venKat kRIshna Solution: ========== SELECT CONCAT(UPPER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, 2))) AS capitalized_name FROM Table1; 03. Case statement SQL Query ========= SELECT Code1, Code2,      CASE         WHEN Code1 = 'A' AND Code2 = 'AA' THEN "A" | "A
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Oozie - Concepts And Architecture

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Oozie is a workflow/coordination system that you can use to manage Apache Hadoop jobs. It is one of the main components of Oozie is the Oozie server — a web application that runs in a Java servlet container (the standard Oozie distribution is using Tomcat).

Oozie is a workflow management-server that works on the Oozie server.

Role of Oozie in Workflow Management in Hadoop Jobs

  1. This server supports reading and executing Workflows, Coordinators, Bundles, and SLA definitions. It implements a set of remote Web Services APIs that can be invoked from Oozie client components and third-party applications.
  2. Add a note where the execution of the server leverages a customizable database.
  3. This database contains Workflow, Coordinator, Bundle, and SLA definitions, as well as execution states and process variables.
  4. The list of currently supported databases includes MySQL, Oracle, and Apache Derby. The Oozie shared library component is located in the Oozie HOME directory and contains code used by the Oozie execution.

Oozie Architecture

oozie architecture


How to work with Oozie in Hadoop Framework

Oozie provides a command-line interface (CLI) that is based on a client component, which is a thin Java wrapper around Oozie Web Services APIs.

These APIs can also be used from third-party applications that have sufficient permissions.
A single Oozie server implements all four functional Oozie components:
  • Oozie Workflow 
  • Oozie Coordinator 
  • Oozie Bundle 
  • Oozie SLA 
  • Oozie server is described in this chapter, starting with what Oozie Workflow is and how you can use it.

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