What is ORC table in Hive?
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What is ORC table in Hive?
The Optimized Row Columnar (ORC) file format provides a highly efficient way to store Hive data. It was designed to overcome limitations of the other Hive file formats. Using ORC files improves performance when Hive is reading, writing, and processing data. ORC file can contain lightweight indexes and bloom filters.
What are the two types of tables 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.
What is the difference between Hive managed table and External table?
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. All the write operations to the Managed tables are performed using Hive SQL commands.
How are Hive tables stored?
Hive stores tables files by default at /user/hive/warehouse location on HDFS file system. You need to create these directories on HDFS before you use Hive. On this location, you can find the directories for all databases you create and subdirectories with the table name you use.
How do I save an ORC table in Hive?
- Create one normal table using textFile format.
- Load the data normally into this table.
- Create one table with the schema of the expected results of your normal hive table using stored as orcfile.
- Insert overwrite query to copy the data from textFile table to orcfile table.
How do I store ORC files in Hive?
ORC is well integrated into Hive, so storing your istari table as ORC is done by adding “STORED AS ORC”.
- CREATE TABLE istari ( name STRING, color STRING ) STORED AS ORC;
- ALTER TABLE istari SET FILEFORMAT ORC;
- ALTER TABLE istari [PARTITION partition_spec] CONCATENATE;
- \% hive –orcfiledump
What is Hive table and difference?
Difference Between Internal vs External Tables
| Internal or Managed Table | External Table |
|---|---|
| Hive owns the metadata, table data by managing the lifecycle of the table | Hive manages the table metadata but not the underlying file. |
How Hive tables are different from pig relation?
Pig is a Procedural Data Flow Language. Hive is a Declarative SQLish Language. It is used to handle structured and semi-structured data. It is mainly used to handle structured data.