BlakeOrth commented on code in PR #8943: URL: https://github.com/apache/arrow-rs/pull/8943#discussion_r2590898300
########## parquet-geospatial/src/types.rs: ########## @@ -0,0 +1,394 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use arrow_schema::{ArrowError, DataType, extension::ExtensionType}; +use serde::{Deserialize, Serialize}; + +/// Hints at the likely Parquet geospatial logical type represented by a [`Metadata`]. +/// +/// Based on the `algorithm` field: +/// - [`Hint::Geometry`]: WKB format with linear/planar edge interpolation +/// - [`Hint::Geography`]: WKB format with explicit non-linear/non-planar edge interpolation +/// +/// See the [Parquet Geospatial specification](https://github.com/apache/parquet-format/blob/master/Geospatial.md) +/// for more details. +#[derive(Copy, Clone, Debug, Serialize, Deserialize)] +pub enum Hint { + /// Geospatial features in WKB format with linear/planar edge interpolation + Geometry, + /// Geospatial features in WKB format with explicit non-linear/non-planar edge interpolation + Geography, +} + +/// The metadata associated with a [`WkbType`]. +#[derive(Clone, Debug, Default, Serialize, Deserialize)] +pub struct Metadata { + /// The Coordinate Reference System (CRS) of the [`WkbType`], if present. + /// + /// This may be a raw string value (e.g., "EPSG:3857") or a JSON object (e.g., PROJJSON). + /// Note: Common lon/lat CRS representations (EPSG:4326, OGC:CRS84) are canonicalized + /// to `None` during serialization to match Parquet conventions. + #[serde(skip_serializing_if = "Option::is_none")] + pub crs: Option<serde_json::Value>, + /// The edge interpolation algorithm of the [`WkbType`], if present. + #[serde(skip_serializing_if = "Option::is_none")] + pub algorithm: Option<String>, Review Comment: Yes, due to the dependency graph we would have to effectively duplicate this enum within the `parquet-geospatial` crate: https://github.com/apache/arrow-rs/pull/8943/files#diff-77b1a58271f532bba48f784fc34eefd52639735547f9e32187dbfbf485ae179dL998 I agree that we already validate the value on each leg of the round-trip, so I don't think we're likely to get unexpected values from the raw string interpretation. It seems like it's mostly a matter of how we'd like to interact with this downstream. An enum results in some duplicated code, but it's probably a bit more idiomatic from a user's perspective. @kylebarron I suspect `geoarrow-rs` is likely to be the primary consumer of this metadata, so I'd probably generally defer to you on what you think the best way to interact with this metadata is. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
