External tables are stored outside the warehouse directory.
They can access data stored in sources such as remote HDFS locations or Azure Storage Volumes.
Whenever we drop the external table, then only the metadata associated with the table will get deleted, the table data remains untouched by Hive..
Where is Hive table located?
use DESCRIBE FORMATTED
to show table information. ps: database. tablename is not supported here. If you use Hue, you can browse the table in the Metastore App and then click on ‘View file location’: that will open the HDFS File Browser in its directory.
How do I find my hive schema?
Viewing Hive Schema and Table MetadataHCATALOG_SCHEMATA lists all of the schemas that have been defined using the HCatalog Connector.HCATALOG_TABLE_LIST contains an overview of all of the tables available from all schemas defined using the HCatalog Connector. … HCATALOG_TABLES contains more in-depth information than HCATALOG_TABLE_LIST.More items…
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…•
How can you tell if a table is internal or 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.
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 can I view Hive table in HDFS?
To list out the databases in Hive warehouse, enter the command ‘show databases’. The database creates in a default location of the Hive warehouse. In Cloudera, Hive database store in a /user/hive/warehouse. Copy the input data to HDFS from local by using the copy From Local command.
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.
Can we update data in Hive?
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 .
Can we truncate external table in hive?
If we want to remove particular row from Hive meta store Table we use DELETE but if we want to delete all the rows from HIVE table we can use TRUNCATE. if you had created a TABLE with EXTERNAL keyword then you can NOT remove all the rows because all data resides outside of Hive Meta store. …
Which property can help deleting the external table with data in Hive?
When you run DROP TABLE on an external table, by default Hive drops only the metadata (schema). If you want the DROP TABLE command to also remove the actual data in the external table, as DROP TABLE does on a managed table, you need to configure the table properties accordingly.
How do you load data into a hive table?
You can load the text file into a textfile Hive table and then insert the data from this table into your sequencefile….You must do this:Create a table stored as text.Insert the text file into the text table.Do a CTAS to create the table stored as a sequence file.Drop the text table if desired.
How do I insert multiple rows in hive?
You may place all new records that you want to insert in a file and load that file into a temp table in Hive. Then using insert overwrite..select command insert those rows into a new partition of your main Hive table. The constraint here is your main table will have to be pre partitioned.
What is 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.
What are external and internal tables in hive?
External table is created for external use as when the data is used outside Hive. Whenever we want to delete the table’s metadata and we want to keep the table’s data as it is, we use an External table. External table only deletes the schema of the table. A managed table is also called an Internal table.
How can I see tables in hive?
Issue the SHOW TABLES command to see the views or tables that exist within workspace. Switch to the Hive schema and issue the SHOW TABLES command to see the Hive tables that exist. Switch to the HBase schema and issue the SHOW TABLES command to see the HBase tables that exist within the schema.
Does Hive store data?
Hive stores data inside /hive/warehouse folder on HDFS if not specified any other folder using LOCATION tag while creation. It is stored in various formats (text,rc,csv,orc etc). Accessing Hive files (data inside tables) through PIG: This can be done even without using HCatalog.
What is difference between external table and managed table 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.