alamb commented on code in PR #7921: URL: https://github.com/apache/arrow-rs/pull/7921#discussion_r2213847359
########## parquet-variant-compute/src/shredding.rs: ########## @@ -0,0 +1,349 @@ +// 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, Fields}; + +// Keywords defined by the shredding spec +pub const METADATA: &str = "metadata"; +pub const VALUE: &str = "value"; +pub const TYPED_VALUE: &str = "typed_value"; + +pub fn validate_value_and_typed_value( + fields: &Fields, + allow_both_null: bool, +) -> Result<(), ArrowError> { + let value_field_res = fields.iter().find(|f| f.name() == VALUE); + let typed_value_field_res = fields.iter().find(|f| f.name() == TYPED_VALUE); + + if !allow_both_null { + if let (None, None) = (value_field_res, typed_value_field_res) { + return Err(ArrowError::InvalidArgumentError( + "Invalid VariantArray: StructArray must contain either `value` or `typed_value` fields or both.".to_string() + )); + } + } + + if let Some(value_field) = value_field_res { + // if !value_field.is_nullable() { + // return Err(ArrowError::InvalidArgumentError( + // "Expected value field to be nullable".to_string(), + // )); + // } + + if value_field.data_type() != &DataType::BinaryView { + return Err(ArrowError::NotYetImplemented(format!( + "VariantArray 'value' field must be BinaryView, got {}", + value_field.data_type() + ))); + } + } + + if let Some(typed_value_field) = fields.iter().find(|f| f.name() == TYPED_VALUE) { + // if !typed_value_field.is_nullable() { + // return Err(ArrowError::InvalidArgumentError( + // "Expected value field to be nullable".to_string(), + // )); + // } + + // this is directly mapped from the spec's parquet physical types + // note, there are more data types we can support + // but for the sake of simplicity, I chose the smallest subset + match typed_value_field.data_type() { + DataType::Boolean + | DataType::Int32 + | DataType::Int64 + | DataType::Float32 + | DataType::Float64 + | DataType::BinaryView => {} + DataType::Union(union_fields, _) => { + union_fields + .iter() + .map(|(_, f)| f.clone()) + .try_for_each(|f| { + let DataType::Struct(fields) = f.data_type().clone() else { + return Err(ArrowError::InvalidArgumentError( + "Expected struct".to_string(), + )); + }; + + validate_value_and_typed_value(&fields, false) + })?; + } + + foreign => { + return Err(ArrowError::NotYetImplemented(format!( + "Unsupported VariantArray 'typed_value' field, got {foreign}" + ))) + } + } + } + + Ok(()) +} + +/// Validates that the provided [`Fields`] conform to the Variant shredding specification. Review Comment: One thing I thought of while reviewing this PR was maybe we could potentially wrap this into its own Structure, like ```rust struct VariantSchema { inner: Fields } ``` And then all this validation logic could be part of the constructor ```rust impl VariantSchema { fn try_new(fields: Fields) -> Result<Self> {... } ... } ``` The benefits of this would be 1. Now we could be sure that a validated schema was always passed to `shred_variant` 2. We would then have a place to put methods on -- such as `VariantSchema::type(path: VariantPath)` for retrieving the type of a particular path, perhaps -- 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: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
