Function decode_column

nodedb/src/engine/timeseries/columnar_segment/codec.rs:94–127

Decode a column file using the codec pipeline.

(
    data: &[u8],
    col_type: ColumnType,
    codec: ResolvedColumnCodec,
)

/// Decode a column file using the codec pipeline.
pub(super) fn decode_column(
    data: &[u8],
    col_type: ColumnType,
    codec: ResolvedColumnCodec,
) -> Result<ColumnData, SegmentError> {
    let map_err = |e: nodedb_codec::CodecError| SegmentError::Corrupt(format!("{codec}: {e}"));

    match col_type {
        ColumnType::Timestamp => {
            let values = nodedb_codec::decode_i64_pipeline(data, codec.into_column_codec())
                .map_err(map_err)?;
            Ok(ColumnData::Timestamp(values))
        }
        ColumnType::Float64 => {
            let values = nodedb_codec::decode_f64_pipeline(data, codec.into_column_codec())
                .map_err(map_err)?;
            Ok(ColumnData::Float64(values))
        }
        ColumnType::Int64 => {
            let values = nodedb_codec::decode_i64_pipeline(data, codec.into_column_codec())
                .map_err(map_err)?;
            Ok(ColumnData::Int64(values))
        }
        ColumnType::Symbol => {
            let raw = nodedb_codec::decode_bytes_pipeline(data, codec.into_column_codec())
                .map_err(map_err)?;
            let ids: Vec<u32> = raw
                .chunks_exact(4)
                .map(|c| u32::from_le_bytes([c[0], c[1], c[2], c[3]]))
                .collect();
            Ok(ColumnData::Symbol(ids))
        }
    }
}