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What is the difference between hive view and a hive external table When should it be used ?

Editor — Tue, 13 Jul 2021 22:18:46 +0000

Difference between hive view and a hive external table When should it be used

A view is a query which is defined as a table.

For example:

CREATE VIEW x AS SELECT * FROM y;

When the user queries table x the query planner combines the queries and executes a single one.

This is something like

SELECT * FROM x;

is translated to

SELECT * FROM y;
Then:

DROP TABLE abc;
If the table is defined as external:

CREATE EXTERNAL table abc (….);

An external table is something totally different. An external TABLE is a table that when DROPPED will NOT remove the physical data.
This is a alternative that affects how data is loaded, controlled, and managed.

Use EXTERNAL tables:

The data is also used outside of Hive.
For example, the data files are browse and processed by an existing program that doesn’t lock the files.
Data needs to stay within the underlying location even after a DROP TABLE.
Pointing multiple patterns at a single data it sets repeats via possible patterns.User can use custom location like ASV.
Hive does not contain own data and control settings, dirs, etc.In Hive existing table (i.e) not modify.

Use INTERNAL tables:

Temporary data needs Hive to manage the table and data.