Module read

APIs to read from ORC

Reading from ORC is essentially composed by:

1. Identify the column type based on the file’s schema
2. Read the stripe (or part of it in projection pushdown)
3. For each column, select the relevant region of the stripe
4. Attach an Iterator to the region

Modules

decode

Contains different iterators that receive a reader (std::io::Read) and return values for each of ORC’s physical types (e.g. boolean).

decompress

Contains Decompressor

Structs

Column

Helper struct used to access the streams associated to an ORC column. Its main use Column::get_stream, to get a stream.

FileMetadata

The file’s metadata.

Functions

read_metadata

read_stripe_column

Reads column from the stripe into a Column. scratch becomes owned by Column, which you can recover via into_inner.

read_stripe_footer

Reads, decompresses and deserializes the stripe’s footer as StripeFooter using scratch as an intermediary memory region.