Hive View

Hive :

Apache Hive is a data warehouse infrastructure built on top of hadoop for providing data summarization, query, and analysis.

View :

A view is a virtual table, that allows a query to be saved and treated like a table. It is a logical construct, as it does not store data like a table.

Example for view :

Create a table in hive and load the data into that table.

(eg)

Create table view_table(no int,name string,salary bigint,city string,country string)row format delimited fields terminated by ‘\t’ lines terminated by ‘\n’ stored  as textfile;

Load data into table :

Syntax:

load data local inpath ‘path/to/file’ into table tablename;

(eg)

load data local inpath ‘/home/geouser/view_table.txt’ into table view_table;

View the table :

select *from view_table;

 

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Create view :

Syntax :

CREATE VIEW [IF NOT EXISTS] view_name [(column_list)]
AS select_statement

(eg)

Create the query to retrieve the details of the employees living in the country usa and store the result in the view.

create view view1 as select * from view_table where country=’usa’;

View the created view table :

select no,name,city from view1;

Alter view :

Syntax : 

        alter view viewname as select_statements;
(eg)

    alter view view1 as select no,name from view_table where country=’usa’;

Drop the view :

Syntax :

drop view viewname;

(eg)

drop view view1;

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