parquet_column_width_needs_data Interface

interface
public module function parquet_column_width_needs_data(reader, name) result(needs_data)

Arguments

Type IntentOptional Attributes Name
type(parquet_reader), intent(in) :: reader

open reader.
character(len=*), intent(in) :: name

column name.

Return Value logical

.true. only for a plain LIST/LARGE_LIST column.

Description

Whether name's vector width can only be determined by reading its data.

.true. for exactly one case: a plain Parquet LIST/LARGE_LIST column, whose rows may each hold a different number of elements, so no width exists in the schema to read. .false. for a scalar column (width 1 by construction) and for a FIXED_SIZE_LIST -- the layout this library always writes, and the one any Arrow-based writer preserves -- whose width is a schema constant. Answered from the schema; reads nothing.