What is Hive input format?
INPUTFORMAT allows you to specify your own Java class should you want Hive to read from a different file format. STORED AS TEXTFILE is easier than writing INPUTFORMAT org.
What is input format and output format in Hive?
InputFormat and OutputFormat – allows you to describe you the original data structure so that Hive could properly map it to the table view. SerDe – represents the class which performs actual translation of data from table view to the low level input-output format structures and opposite.
Which is the default Serde in Hive?
user (uid int,name string); this ddl statement without any format and delimiters then hive creates user table with default serde (serialize,deserializer ). This serde instructs hive on how to process a record (Row) and serde library is inbuilt to Hadoop API.
What is default file format for Hive?
hive use Text as default format, a extra “store as parquet/ORC” clause have to be added if parquet/ORC file format is needed.
Why ORC file is used 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.
What is input format class?
The InputFormat class is one of the fundamental classes in the Hadoop MapReduce framework which provides the following functionality: The files or other objects that should be used for input is selected by the InputFormat.
What is the default input format in Hadoop?
TextInputFormat is the default input format of MapReduce in Hadoop. TextInputFormat considers each line of each input file as another record and performs no parsing. This is mainly used for unformatted data or line-based records like log files.
What is SerDe in hive?
SerDe is short for Serializer/Deserializer. Hive uses the SerDe interface for IO. A SerDe allows Hive to read in data from a table, and write it back out to HDFS in any custom format. Anyone can write their own SerDe for their own data formats.
What is a record in Hadoop?
I want to understand the definition of Record in MapReduce Hadoop, for data types other than Text. Typically, for Text data a record is full line terminated by new line.
What is serializer and deserializer in Hive?
SerDe is short for Serializer/Deserializer. The interface handles both serialization and deserialization and also interpreting the results of serialization as individual fields for processing. A SerDe allows Hive to read in data from a table, and write it back out to HDFS in any custom format.
What are different file formats in Hive?
Hive Data Formats
| File Format | Description | Profile |
|---|---|---|
| TextFile | Flat file with data in comma-, tab-, or space-separated value format or JSON notation. | Hive, HiveText |
| SequenceFile | Flat file consisting of binary key/value pairs. | Hive |
| RCFile | Record columnar data consisting of binary key/value pairs; high row compression rate. | Hive, HiveRC |
Which is the default input format in hive?
TextInputFormat is the default input format used in a hive table. But if the data arrives in a different format or if certain records have to be rejected, we have to write a custom InputFormat and RecordReader.
How to create a hiveoutputdescription in Hadoop?
Create a HiveOutputDescription object. Fill it with information about the table to write to (with database and partition). Initialize HiveApiOutputFormat with the information. Go to town using HiveApiOutputFormat with your Hadoop-compatible writing system.
How does the hiveapiinputformat read from multiple tables?
HiveApiInputFormat supports reading from multiple tables by having a concept of profiles. Each profile stores its input description in a separate section, and the HiveApiInputFormat has a member which tells it which profile to read from. When initializing the input data in HiveApiInputFormat you can pair it with a profile.