Samyak2 commented on code in PR #7919: URL: https://github.com/apache/arrow-rs/pull/7919#discussion_r2208067247
########## parquet-variant-compute/src/variant_get.rs: ########## @@ -0,0 +1,202 @@ +// 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 std::sync::Arc; + +use arrow::{ + array::{Array, ArrayRef}, + compute::CastOptions, + error::Result, +}; +use arrow_schema::{ArrowError, Field}; +use parquet_variant::path::VariantPath; + +use crate::{VariantArray, VariantArrayBuilder}; + +/// Returns an array with the specified path extracted from the variant values. +/// +/// The return array type depends on the `as_type` field of the options parameter +/// 1. `as_type: None`: a VariantArray is returned. The values in this new VariantArray will point +/// to the specified path. +/// 2. `as_type: Some(<specific field>)`: an array of the specified type is returned. +pub fn variant_get(input: &ArrayRef, options: GetOptions) -> Result<ArrayRef> { + let variant_array: &VariantArray = input.as_any().downcast_ref().ok_or_else(|| { + ArrowError::InvalidArgumentError( + "expected a VariantArray as the input for variant_get".to_owned(), + ) + })?; + + if let Some(as_type) = options.as_type { + return Err(ArrowError::NotYetImplemented(format!( + "getting a {} from a VariantArray is not implemented yet", + as_type + ))); + } + + let mut builder = VariantArrayBuilder::new(variant_array.len()); + for i in 0..variant_array.len() { + let new_variant = variant_array.value(i); Review Comment: Just to understand this -- is this what you're suggesting? - We add a new `get_path` method in `VariantArray` that does this: - For each row, look up the type of the variant and perform the pathing without decoding. So, for example, if it's a `VariantObject` and there's a `VariantPathElement::Field` path, it would get the offset for the given field (not sure how yet) and advance the `value` slice by that much. - We would then create a new `VariantArray` with the metadata directly copied over and the value copied starting from the advanced slice. - For shredded variants, if the path ends up on a shredded value, what would be the expected behavior? I'm guessing that the shredded fields will be represented as an Array of the concrete type (an `Int32Array` for example) and not a `VariantArray`. Will we wrap these in a `VariantArray` and send it back? This is one case where having the path + cast in the same operation would help. - This `variant_get` would then simply re-use `VariantArray::get_path` and perform the appropriate cast. -- 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
