Impala - Alter View


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The Alter View statement of Impala is used to change a view. Using this statement, you can change the name of a view, change the database, and the query associated with it.

Since a view is a logical construct, no physical data will be affected by the alter view query.

Syntax

Following is the syntax of the Alter View statement

ALTER VIEW database_name.view_name as Select statement

Example

For example, assume we have a view named customers_view in the my_db database in Impala with the following contents.

+----------+-----+ 
| name     | age | 
+----------+-----+ 
| Komal    | 22  | 
| Khilan   | 25  | 
| Ramesh   | 32  | 
| Hardik   | 27  | 
| Chaitali | 25  | 
| kaushik  | 23  | 
+----------+-----+

Following is an example of Alter View Statement. In this example, we are including the columns id, name, and salary instead of name and age to the customers_view.

[quickstart.cloudera:21000] > Alter view customers_view as select id, name, 
salary from customers;

On executing the above query, Impala does the specified changes to the customers_view, displaying the following message.

Query: alter view customers_view as select id, name, salary from customers

Verification

You can verify the contents of the view named customers_view, using the select statement as shown below.

[quickstart.cloudera:21000] > select * from customers_view;
Query: select * from customers_view

This will produce the following result.

+----+----------+--------+ 
| id | name     | salary | 
+----+----------+--------+
| 3  | kaushik  | 30000  | 
| 2  | Khilan   | 15000  | 
| 5  | Hardik   | 40000  | 
| 6  | Komal    | 32000  | 
| 1  | Ramesh   | 20000  | 
| 4  | Chaitali | 35000  | 
+----+----------+--------+ 
Fetched 6 row(s) in 0.69s

Altering a View using Hue

Open Impala Query editor, select the context as my_db, and type the Alter View statement in it and click on the execute button as shown in the following screenshot.

Altering a View

After executing the query, the view named sample will be altered accordingly.



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