Types

1: Logical Types

The types supported by the file format are intended to be as minimal as possible, with a focus on how the types effect on disk storage. For example, 16-bit ints are not explicitly supported in the storage format since they are covered by 32-bit ints with an efficient encoding. This reduces the complexity of implementing readers and writers for the format. The types are:

  - BOOLEAN: 1 bit boolean
  - INT32: 32 bit signed ints
  - INT64: 64 bit signed ints
  - INT96: 96 bit signed ints
  - FLOAT: IEEE 32-bit floating point values
  - DOUBLE: IEEE 64-bit floating point values
  - BYTE_ARRAY: arbitrarily long byte arrays
  - FIXED_LEN_BYTE_ARRAY: fixed length byte arrays

1 - Logical Types

Logical types are used to extend the types that parquet can be used to store, by specifying how the primitive types should be interpreted. This keeps the set of primitive types to a minimum and reuses parquet’s efficient encodings. For example, strings are stored as byte arrays (binary) with a UTF8 annotation. These annotations define how to further decode and interpret the data. Annotations are stored as LogicalType fields in the file metadata and are documented in LogicalTypes.md.