In Apache Hive, the STORED AS clause is used to specify the file format for data storage when creating tables. The choice of file format can have an impact on the performance, storage, and compatibility of the data in Hive. Here’s an overview of some of the file formats that can be specified using the STORED AS clause in Hive:
- Text file format (STORED AS TEXTFILE): Text file format is the default file format in Hive, which stores data in plain text files with each line representing a row of data. Text file format is suitable for storing and processing unstructured or semi-structured data, but it can be inefficient for large datasets or complex queries.
- Sequence file format (STORED AS SEQUENCEFILE): Sequence file format is a binary file format in Hive that is optimized for storing large datasets with complex data types. Sequence file format stores data as binary key-value pairs, which can be compressed for storage efficiency.
- ORC file format (STORED AS ORC): ORC (Optimized Row Columnar) file format is a highly efficient columnar storage format in Hive that reduces data storage and improves query performance. ORC format compresses data at different levels and supports advanced features like predicate pushdown and indexing, making it a preferred file format for big data processing.
- Parquet file format (STORED AS PARQUET): Parquet file format is another columnar storage format in Hive that is optimized for processing large datasets. Parquet format stores data in a highly compressed and efficient columnar structure, enabling faster queries and reduced storage costs.
- Avro file format (STORED AS AVRO): Avro file format is a data serialization system in Hive that stores data in a compact binary format. Avro format supports schema evolution and is designed to work well with Hadoop ecosystems like Hive.
In summary, the choice of file format in Hive using STORED AS clause depends on the nature of the data being stored and the performance requirements of the queries. Hive provides a range of file formats to choose from, each with its advantages and disadvantages.