How do I query an external table in Hive?

How do I view an external table 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.

What is the location for external table in Hive?

As you can see, the warehouse is located at the NYSE_daily directory in your home directory in HDFS. Also, the table type is EXTERNAL. When we drop an external table, underlying data does not get deleted.

How do I find a specific table in Hive?

When programming on Hive by Spark SQL, you can use following method to check whether Hive table exists….1.1) start the **hiveserver** before running the query 1.2) you have to run two queries 1.2.

  1. USE <database_name> 1.2.
  2. SHOW TABLES LIKE 'table_name' 1.2.
  3. Then you check your result using Result set.

Jan 19, 2014

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

We can identify the internal or External tables using the DESCRIBE FORMATTED table_name statement in the Hive, which will display either MANAGED_TABLE or EXTERNAL_TABLE depending on the table type.

What is an external table in hive?

You use an external table, which is a table that Hive does not manage, to import data from a file on a file system, into Hive. In contrast to the Hive managed table, an external table keeps its data outside the Hive metastore. … Hive does not manage, or restrict access, to the actual external data.

How do I drop an external table in Hive?

Drop an external table along with data

  1. Create a CSV file of data you want to query in Hive.
  2. Start Hive.
  3. Run DROP TABLE on the external table. DROP TABLE names_text;
  4. Prevent data in external table from being deleted by a DROP TABLE statement. ALTER TABLE addresses_text SET TBLPROPERTIES ('external.table.purge'='false');

How do you describe an external table in Hive?

An external table is a table for which Hive does not manage storage. If you delete an external table, only the definition in Hive is deleted. The data remains. An internal table is a table that Hive manages.

How do I get all columns of a table in Hive?

use desc tablename from Hive CLI or beeline to get all the column names.

Where the table data resides in the file system?

/usr/hive/warehouse is the default location for all managed tables. External tables may be stored at a different location. describe formatted <table_name> is the hive shell command which can be use more generally to find the location of data pertaining to a hive table.

What is an external table?

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.

What happens when an external table is dropped in hive?

When you drop a table from Hive Metastore, it removes the table/column data and their metadata. It can be a normal table (stored in Metastore) or an external table (stored in local file system); Hive treats both in the same manner, irrespective of their types.

What are managed and external tables in Hive?

Managed tables are Hive owned tables where the entire lifecycle of the tables' data are managed and controlled by Hive. External tables are tables where Hive has loose coupling with the data. … If a Managed table or partition is dropped, the data and metadata associated with that table or partition are deleted.

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