External vs managed tables in Hadoop - Quick Revision & Key Differences

Recall & Review

beginner

What is a managed table in Hadoop?

A managed table is a table where Hadoop manages both the metadata and the data files. When you drop the table, both the metadata and the data are deleted.

beginner

What is an external table in Hadoop?

An external table stores metadata in Hadoop but the data files are stored outside Hadoop's control. Dropping the table deletes only the metadata, not the data files.

intermediate

When should you use an external table instead of a managed table?

Use an external table when you want to keep the data files even if the table is dropped, or when data is shared across multiple systems.

beginner

What happens to data files when you drop a managed table?

The data files are deleted along with the table metadata because Hadoop manages both.

beginner

How does Hadoop treat data files of an external table when the table is dropped?

Hadoop deletes only the metadata but leaves the data files untouched in their original location.

What happens to data files when you drop an external table in Hadoop?

A Only metadata is deleted

B Data files are deleted

C Both data and metadata are deleted

D Nothing happens

Dropping an external table deletes only the metadata, not the data files.

Which type of table does Hadoop fully manage, including data files?

A Managed table

B External table

C Temporary table

D Partitioned table

Managed tables have both metadata and data files managed by Hadoop.

When is it best to use an external table?

A When you want Hadoop to delete data automatically

B When you want to store data inside Hadoop only

C When you want faster queries

D When data is shared or needs to persist beyond table deletion

External tables keep data files even if the table is dropped, useful for shared or persistent data.

If you want Hadoop to delete data files when dropping a table, which table type should you choose?

A External table

B Managed table

C Temporary table

D View

Managed tables delete both metadata and data files when dropped.

Which statement is true about external tables?

A They store data inside Hadoop's warehouse directory

B They manage both data and metadata

C They only manage metadata, data is external

D They cannot be dropped

External tables manage only metadata; data files remain outside Hadoop's control.

Explain the key differences between external and managed tables in Hadoop.

Think about what happens to data files when you drop each table type.

Describe a real-life scenario where using an external table is better than a managed table.

Consider when you want to keep data safe even if the table is removed.