Impala Select Statement – How to Fetch Records using Hue

1. Impala Select Statement – Objective

It is possible to fetch the data from one or more tables in a database in Impala. For that, we use Impala Select Statement. So, in this article, we will discuss, how we can fetch data with Impala Select Statement. Also, we will cover its syntax, usage as well as Example to understand it well.
So, let’s start How Impala Select Statement.

Impala Select Statement - How to Fetch Records using Hue

Impala Select Statement – How to Fetch Records using Hue

2. How to use Impala Select Statement?

Basically, to performs queries, retrieving data from one or more tables and producing result sets consisting of rows and columns, we use Impala  Select Statement. In addition, it also typically ends with a SELECT statement, to define data to copy from one table to another.
Let’s Have a look at Impala DROP DATABASE Statement
To be more specific, to fetch the data from one or more tables in a database, we use  Impala  Select Statement. Also, returns data in the form of tables.

i. Impala SELECT queries support

  • SQL data types: BOOLEAN, TINYINT, SMALLINT, INT, BIGINT, FLOAT, DOUBLE, TIMESTAMP, STRING.
  • Before the SELECT keyword, there is an optional WITH clause. By using this we can define a subquery whose name or column names can be referenced from later in the main query. 
  • DISTINCT clause per query. 
  • Subqueries in a FROM clause.
  • WHERE, GROUP BY, HAVING clauses.
  • ORDER BY

ii. Cancellation

It is possible to cancel it. That implies it Can be canceled. Basically, we use Ctrl-C from the impala-shell interpreter, in order to cancel this statement. Hence the Cancel button from the Watch page in Hue, Actions > Cancel from the Queries list in Cloudera Manager. Also, Cancel from the list of in-flight queries (for a particular node) on the Queries tab in the Impala web UI (port 25000).
Read about How Impala CREATE TABLE Statement

iii. Syntax of Impala Select Statements

Here, is the syntax of Impala – Select Statement, below;

SELECT column1, column2, columnN from table_name;

So, column1, column2…are the fields of a table whose values we want to fetch. So, we can use the following syntax if we want to fetch all the fields available in the field −

SELECT * FROM table_name;

iv. Example of Impala Select Statement

Let’s take one example of Impala Select statement suppose we have a table named Employees in Impala. Here,  is the data −

idnameageaddresssalary
1shubham32delhi20000
2monika25mumbai15000
3kajal27alirajpur40000
4revti25indore35000
5shreyash23pune30000
6mehul22heydrabad32000

So, using select statement, we can fetch the id, name, and age of all the records of the Employees table.

[quickstart.cloudera:21000] > select id, name, age from Employees

Do you Know – Impala Describe Statement
Also, Impala fetches id, name, the age of all the records from the specified table and displays them, on executing the above query.

Query: select id,name,age from Employees
idnameage
1shubham32
2monika25
3kajal27
4revti25
5shreyash23
6mehul22

Fetched 6 row(s) in 0.66s
Moreover, using the select query, we can also fetch all the records from the Employees table.

[quickstart.cloudera:21000] > select name, age from Employees;
Query: select * from Employees

Let’s Understand Impala CREATE VIEW Statement
Basically, Impala fetches and displays all the records from the specified table, on executing the above query.

idnameageaddresssalary
1shubham32delhi20000
2monika25mumbai15000
3kajal27alirajpur40000
4revti25indore35000
5shreyash23pune30000
6mehul22heydrabad32000

Fetched 6 row(s) in 0.66s

Hadoop Quiz

Get the most demanding skills of IT Industry - Learn Hadoop

3. Fetching the Records using Hue

There are several steps you have to follow while fetching the records using Hue. Such as:

  • At first,  type the select Statement in Impala Query editor. Further, click on the execute button.
  • Afterward,  we can see the list of the records of the specified table, just after executing the query, once you scroll down and select the Results tab.

Read More about Impala Select a Database using Hue Browser

So, this was all about Impala Select Statements. Hope you like our explanation.

4. Conclusion – Impala Select Statement

As a result, we have seen the whole concept of Impala – Select Statement. Still, if any doubt occurs in how to create impala database, feel free to ask in the comment section.
See also –  Impala SHOW Statement
For reference

Leave a Reply

Your email address will not be published. Required fields are marked *