alamb commented on code in PR #8021:
URL: https://github.com/apache/arrow-rs/pull/8021#discussion_r2260892295
##########
parquet-variant-compute/src/variant_array.rs:
##########
@@ -186,13 +340,11 @@ impl Array for VariantArray {
}
fn slice(&self, offset: usize, length: usize) -> ArrayRef {
- let slice = self.inner.slice(offset, length);
- let met = self.metadata_ref.slice(offset, length);
- let val = self.value_ref.slice(offset, length);
+ let inner = self.inner.slice(offset, length);
+ let shredding_state = self.shredding_state.slice(offset, length);
Arc::new(Self {
Review Comment:
I agree I don't expect any measurable performance improvement
##########
parquet-variant-compute/src/variant_get/output/primitive.rs:
##########
@@ -0,0 +1,166 @@
+// 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 crate::variant_get::output::OutputBuilder;
+use crate::VariantArray;
+use arrow::error::Result;
+
+use arrow::array::{
+ Array, ArrayRef, ArrowPrimitiveType, AsArray, BinaryViewArray,
NullBufferBuilder,
+ PrimitiveArray,
+};
+use arrow::compute::{cast_with_options, CastOptions};
+use arrow::datatypes::Int32Type;
+use arrow_schema::{ArrowError, FieldRef};
+use parquet_variant::{Variant, VariantPath};
+use std::marker::PhantomData;
+use std::sync::Arc;
+
+/// Trait for Arrow primitive types that can be used in the output builder
+///
+/// This just exists to add a generic way to convert from Variant to the
primitive type
+pub(super) trait ArrowPrimitiveVariant: ArrowPrimitiveType {
+ /// Try to extract the primitive value from a Variant, returning None if it
+ /// cannot be converted
+ ///
+ /// TODO: figure out how to handle coercion/casting
+ fn from_variant(variant: &Variant) -> Option<Self::Native>;
+}
+
+/// Outputs Primitive arrays
+pub(super) struct PrimitiveOutputBuilder<'a, T: ArrowPrimitiveVariant> {
+ /// What path to extract
+ path: VariantPath<'a>,
+ /// Returned output type
+ as_type: FieldRef,
+ /// Controls the casting behavior (e.g. error vs substituting null on cast
error).
+ cast_options: CastOptions<'a>,
+ /// Phantom data for the primitive type
+ _phantom: PhantomData<T>,
+}
+
+impl<'a, T: ArrowPrimitiveVariant> PrimitiveOutputBuilder<'a, T> {
+ pub(super) fn new(
+ path: VariantPath<'a>,
+ as_type: FieldRef,
+ cast_options: CastOptions<'a>,
+ ) -> Self {
+ Self {
+ path,
+ as_type,
+ cast_options,
+ _phantom: PhantomData,
+ }
+ }
+}
+
+impl<'a, T: ArrowPrimitiveVariant> OutputBuilder for
PrimitiveOutputBuilder<'a, T> {
+ fn partially_shredded(
+ &self,
+ variant_array: &VariantArray,
+ _metadata: &BinaryViewArray,
+ _value_field: &BinaryViewArray,
+ typed_value: &ArrayRef,
+ ) -> arrow::error::Result<ArrayRef> {
+ // build up the output array element by element
+ let mut nulls = NullBufferBuilder::new(variant_array.len());
+ let mut values = Vec::with_capacity(variant_array.len());
+ let typed_value =
+ cast_with_options(typed_value, self.as_type.data_type(),
&self.cast_options)?;
+ // downcast to the primitive array (e.g. Int32Array, Float64Array, etc)
+ let typed_value = typed_value.as_primitive::<T>();
+
+ for i in 0..variant_array.len() {
+ if variant_array.is_null(i) {
+ nulls.append_null();
+ values.push(T::default_value()); // not used, placeholder
+ continue;
+ }
+
+ // if the typed value is null, decode the variant and extract the
value
+ if typed_value.is_null(i) {
+ // todo follow path
+ let variant = variant_array.value(i);
+ let Some(value) = T::from_variant(&variant) else {
+ if self.cast_options.safe {
+ // safe mode: append null if we can't convert
+ nulls.append_null();
+ values.push(T::default_value()); // not used,
placeholder
+ continue;
+ } else {
+ return Err(ArrowError::CastError(format!(
+ "Failed to extract primitive of type {} from
variant {:?} at path {:?}",
+ self.as_type.data_type(),
+ variant,
+ self.path
+ )));
+ }
+ };
+
+ nulls.append_non_null();
+ values.push(value)
+ } else {
+ // otherwise we have a typed value, so we can use it directly
+ nulls.append_non_null();
+ values.push(typed_value.value(i));
+ }
+ }
+
+ let nulls = nulls.finish();
+ let array = PrimitiveArray::<T>::new(values.into(), nulls)
+ .with_data_type(self.as_type.data_type().clone());
+ Ok(Arc::new(array))
+ }
+
+ fn fully_shredded(
+ &self,
+ _variant_array: &VariantArray,
+ _metadata: &BinaryViewArray,
+ typed_value: &ArrayRef,
+ ) -> arrow::error::Result<ArrayRef> {
+ // if the types match exactly, we can just return the typed_value
+ if typed_value.data_type() == self.as_type.data_type() {
+ Ok(typed_value.clone())
+ } else {
+ // TODO: try to cast the typed_value to the desired type?
+ Err(ArrowError::NotYetImplemented(format!(
Review Comment:
Yeah, I am not sure what to do with this casting -- I will file a follow on
ticket for us to sort it out
##########
parquet-variant-compute/src/variant_get/mod.rs:
##########
@@ -0,0 +1,430 @@
+// 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::{
+ array::{Array, ArrayRef},
+ compute::CastOptions,
+ error::Result,
+};
+use arrow_schema::{ArrowError, FieldRef};
+use parquet_variant::VariantPath;
+
+use crate::variant_array::ShreddingState;
+use crate::variant_get::output::instantiate_output_builder;
+use crate::VariantArray;
+
+mod output;
+
+/// 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(),
+ )
+ })?;
+
+ // Create the output writer based on the specified output options
+ let output_builder = instantiate_output_builder(options.clone())?;
+
+ // Dispatch based on the shredding state of the input variant array
+ match variant_array.shredding_state() {
Review Comment:
Yeah, exactly, this I think is the key challenge of this code -- each
different type of output needs to handle all the possible input shredding types
as well.
##########
parquet-variant-compute/src/variant_get/output/mod.rs:
##########
Review Comment:
I think this aligns with my thinking and is nicely described -- I will use
it as the base for the next set of tickets perhaps
##########
parquet-variant-compute/src/variant_get/output/primitive.rs:
##########
@@ -0,0 +1,166 @@
+// 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 crate::variant_get::output::OutputBuilder;
+use crate::VariantArray;
+use arrow::error::Result;
+
+use arrow::array::{
+ Array, ArrayRef, ArrowPrimitiveType, AsArray, BinaryViewArray,
NullBufferBuilder,
+ PrimitiveArray,
+};
+use arrow::compute::{cast_with_options, CastOptions};
+use arrow::datatypes::Int32Type;
+use arrow_schema::{ArrowError, FieldRef};
+use parquet_variant::{Variant, VariantPath};
+use std::marker::PhantomData;
+use std::sync::Arc;
+
+/// Trait for Arrow primitive types that can be used in the output builder
+///
+/// This just exists to add a generic way to convert from Variant to the
primitive type
+pub(super) trait ArrowPrimitiveVariant: ArrowPrimitiveType {
+ /// Try to extract the primitive value from a Variant, returning None if it
+ /// cannot be converted
+ ///
+ /// TODO: figure out how to handle coercion/casting
+ fn from_variant(variant: &Variant) -> Option<Self::Native>;
+}
+
+/// Outputs Primitive arrays
+pub(super) struct PrimitiveOutputBuilder<'a, T: ArrowPrimitiveVariant> {
+ /// What path to extract
+ path: VariantPath<'a>,
+ /// Returned output type
+ as_type: FieldRef,
+ /// Controls the casting behavior (e.g. error vs substituting null on cast
error).
+ cast_options: CastOptions<'a>,
+ /// Phantom data for the primitive type
+ _phantom: PhantomData<T>,
+}
+
+impl<'a, T: ArrowPrimitiveVariant> PrimitiveOutputBuilder<'a, T> {
+ pub(super) fn new(
+ path: VariantPath<'a>,
+ as_type: FieldRef,
+ cast_options: CastOptions<'a>,
+ ) -> Self {
+ Self {
+ path,
+ as_type,
+ cast_options,
+ _phantom: PhantomData,
+ }
+ }
+}
+
+impl<'a, T: ArrowPrimitiveVariant> OutputBuilder for
PrimitiveOutputBuilder<'a, T> {
+ fn partially_shredded(
+ &self,
+ variant_array: &VariantArray,
+ _metadata: &BinaryViewArray,
+ _value_field: &BinaryViewArray,
+ typed_value: &ArrayRef,
+ ) -> arrow::error::Result<ArrayRef> {
+ // build up the output array element by element
+ let mut nulls = NullBufferBuilder::new(variant_array.len());
+ let mut values = Vec::with_capacity(variant_array.len());
+ let typed_value =
+ cast_with_options(typed_value, self.as_type.data_type(),
&self.cast_options)?;
+ // downcast to the primitive array (e.g. Int32Array, Float64Array, etc)
+ let typed_value = typed_value.as_primitive::<T>();
+
+ for i in 0..variant_array.len() {
+ if variant_array.is_null(i) {
+ nulls.append_null();
+ values.push(T::default_value()); // not used, placeholder
+ continue;
+ }
+
+ // if the typed value is null, decode the variant and extract the
value
+ if typed_value.is_null(i) {
+ // todo follow path
Review Comment:
> We'd either have to do all the pathing here (recursively), or caller would
have to to extract the struct/array once and recurse on its fields.
Yes, I was imagining that this would do the pathing here on each row -- I am
not sure what you mean by extract the struct array (as I don't think we can
extract variants as structs in general, as the structures vary row by row)
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