Question: What Is Difference Between External Table And Managed Table In Hive?

What are external tables?

An external table is a table whose data come from flat files stored outside of the database.

Oracle can parse any file format supported by the SQL*Loader..

How do you make an external snowflake table?

Steps to Create Snowflake External TableCreate File Format.Create External Stage for External Storage (S3, GCP bucket, Azure Blob)Define or Create External Table using external stage location.

What are the different types of tables available in hive?

Fundamentally, Hive knows two different types of tables: Internal table and the External table. The Internal table is also known as the managed table.

How do I rename an external table in hive?

ALTER TABLE table_name RENAME TO new_table_name; This statement lets you change the name of a table to a different name. As of version 0.6, a rename on a managed table moves its HDFS location as well. (Older Hive versions just renamed the table in the metastore without moving the HDFS location.)

Can we convert external table to managed table in hive?

2 Answers. You can copy your data files from the Hive data location to the location you planned to store your external table, drop the table and re-create it as external.

How do I truncate an external table?

You cannot delete or truncate an external table. However, you can alter and drop the table definition. Dropping an external table drops the table definition, but it does not delete the data file that is associated with the table. To drop an external table, use the DROP statement.

How do I create a managed table in hive?

When we create a table in Hive without specifying it as external, by default we will get a Managed table. If we create a table as a managed table, the table will be created in a specific location in HDFS. By default, the table data will be created in /usr/hive/warehouse directory of HDFS.

How can you tell if a table is external in hive?

For external tables Hive assumes that it does not manage the data. Managed or external tables can be identified using the DESCRIBE FORMATTED table_name command, which will display either MANAGED_TABLE or EXTERNAL_TABLE depending on table type.

When would you choose to create an external Hive table?

Use EXTERNAL tables when:The data is also used outside of Hive. … Data needs to remain in the underlying location even after a DROP TABLE. … You want to use a custom location such as ASV.Hive should not own data and control settings, dirs, etc., you have another program or process that will do those things.More items…•

Can we truncate external table in hive?

Truncate Hive target tables to delete the table contents. You can truncate internal and external Hive tables in the Hadoop environment. To truncate the entire Hive table, choose the option to truncate the target table.

Can we insert data into Hive external table?

Hive apparently supports INSERT…VALUES starting in Hive 0.14. It’s a limitation of hive. You can use following lines of code to insert values into an already existing table. … Although, you can load your CSV file into HDFS and tell Hive to treat it as an external table.

How do you describe a table in hive?

There are three ways to describe a table in Hive. To see table primary info of Hive table, use describe table_name; command. To see more detailed information about the table, use describe extended table_name; command. To see code in a clean manner use describe formatted table_name; command to see all information.

How can we convert external table to internal in hive?

Apache HiveUse case: There is lot of data in the locally managed table and we want to convert those table into external table because we are working on a use case where our spark and home grown application has trouble reading locally managed tables.Solution: alter table table_name SET TBLPROPERTIES(‘EXTERNAL’=’TRUE’);More items…•

What is the difference between internal table and external table in hive?

So, internal tables are used when we want Hive to completely manage table and the data. While the external tables are used when the data is also used outside of Hive.

What is external table in Snowflake?

External tables store file-level metadata about the data files, such as the filename, a version identifier and related properties. … This enables querying data stored in files in an external stage as if it were inside a database.

Can we create external table without location?

When you create external table with out location , the data will be stored in the hive default location. … If you don’t specify location for the external table, it will be stored under default hive warehouse location.

Can we delete data from Hive table?

Hive doesn’t support updates (or deletes), but it does support INSERT INTO, so it is possible to add new rows to an existing table. Delete has been recently added in Hive version 0.14 Deletes can only be performed on tables that support ACID Below is the link from Apache .

How do I drop an external table in hive?

Do alter table on all tables and change the external table to internal table then drop the table. hive> drop table; //now the table is internal if you drop the table data will be dropped automatically.