Jefffrey commented on code in PR #9379:
URL: https://github.com/apache/arrow-rs/pull/9379#discussion_r2787539036
##########
arrow-json/src/reader/mod.rs:
##########
@@ -2857,4 +2860,187 @@ mod tests {
"Json error: whilst decoding field 'a': failed to parse \"a\" as
Int32".to_owned()
);
}
+
+ #[test]
+ fn test_read_run_end_encoded() {
+ let buf = r#"
+ {"a": "x"}
+ {"a": "x"}
+ {"a": "y"}
+ {"a": "y"}
+ {"a": "y"}
+ "#;
+
+ let ree_type = DataType::RunEndEncoded(
+ Arc::new(Field::new("run_ends", DataType::Int32, false)),
+ Arc::new(Field::new("values", DataType::Utf8, true)),
+ );
+ let schema = Arc::new(Schema::new(vec![Field::new("a", ree_type,
true)]));
+ let batches = do_read(buf, 1024, false, false, schema);
+ assert_eq!(batches.len(), 1);
+
+ let col = batches[0].column(0);
+ let run_array = col
+ .as_any()
+
.downcast_ref::<arrow_array::RunArray<arrow_array::types::Int32Type>>()
+ .unwrap();
+
+ // 5 logical values compressed into 2 runs
+ assert_eq!(run_array.len(), 5);
+ assert_eq!(run_array.run_ends().values(), &[2, 5]);
+
+ let values = run_array
Review Comment:
and `as_string` here
##########
arrow-json/src/reader/mod.rs:
##########
@@ -2857,4 +2860,187 @@ mod tests {
"Json error: whilst decoding field 'a': failed to parse \"a\" as
Int32".to_owned()
);
}
+
+ #[test]
+ fn test_read_run_end_encoded() {
+ let buf = r#"
+ {"a": "x"}
+ {"a": "x"}
+ {"a": "y"}
+ {"a": "y"}
+ {"a": "y"}
+ "#;
+
+ let ree_type = DataType::RunEndEncoded(
+ Arc::new(Field::new("run_ends", DataType::Int32, false)),
+ Arc::new(Field::new("values", DataType::Utf8, true)),
+ );
+ let schema = Arc::new(Schema::new(vec![Field::new("a", ree_type,
true)]));
+ let batches = do_read(buf, 1024, false, false, schema);
+ assert_eq!(batches.len(), 1);
+
+ let col = batches[0].column(0);
+ let run_array = col
+ .as_any()
+
.downcast_ref::<arrow_array::RunArray<arrow_array::types::Int32Type>>()
+ .unwrap();
+
+ // 5 logical values compressed into 2 runs
+ assert_eq!(run_array.len(), 5);
+ assert_eq!(run_array.run_ends().values(), &[2, 5]);
+
+ let values = run_array
+ .values()
+ .as_any()
+ .downcast_ref::<StringArray>()
+ .unwrap();
+ assert_eq!(values.len(), 2);
+ assert_eq!(values.value(0), "x");
+ assert_eq!(values.value(1), "y");
+ }
+
+ #[test]
+ fn test_run_end_encoded_roundtrip() {
+ let run_ends = arrow_array::Int32Array::from(vec![3, 5, 7]);
+ let values = StringArray::from(vec![Some("a"), None, Some("b")]);
+ let ree =
+
arrow_array::RunArray::<arrow_array::types::Int32Type>::try_new(&run_ends,
&values)
+ .unwrap();
+
+ let schema = Arc::new(Schema::new(vec![Field::new(
+ "c",
+ ree.data_type().clone(),
+ true,
+ )]));
+ let batch = RecordBatch::try_new(schema.clone(),
vec![Arc::new(ree)]).unwrap();
+
+ // Write to JSON
+ let mut buf = Vec::new();
+ {
+ let mut writer = crate::writer::LineDelimitedWriter::new(&mut buf);
+ writer.write_batches(&[&batch]).unwrap();
Review Comment:
it feels like this test best belongs in the write module since it uses write
functionality 🤔
##########
arrow-json/src/reader/run_end_array.rs:
##########
@@ -0,0 +1,150 @@
+// 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::reader::tape::Tape;
+use crate::reader::{ArrayDecoder, DecoderContext};
+use arrow_array::Array;
+use arrow_data::transform::MutableArrayData;
+use arrow_data::{ArrayData, ArrayDataBuilder};
+use arrow_schema::{ArrowError, DataType};
+
+pub struct RunEndEncodedArrayDecoder {
+ data_type: DataType,
+ decoder: Box<dyn ArrayDecoder>,
+}
+
+impl RunEndEncodedArrayDecoder {
+ pub fn new(
+ ctx: &DecoderContext,
+ data_type: &DataType,
+ is_nullable: bool,
+ ) -> Result<Self, ArrowError> {
+ let values_field = match data_type {
+ DataType::RunEndEncoded(_, v) => v,
+ _ => unreachable!(),
+ };
+ let decoder = ctx.make_decoder(
+ values_field.data_type(),
+ values_field.is_nullable() || is_nullable,
+ )?;
+
+ Ok(Self {
+ data_type: data_type.clone(),
+ decoder,
+ })
+ }
+}
+
+impl ArrayDecoder for RunEndEncodedArrayDecoder {
+ fn decode(&mut self, tape: &Tape<'_>, pos: &[u32]) -> Result<ArrayData,
ArrowError> {
+ let run_ends_type = match &self.data_type {
+ DataType::RunEndEncoded(r, _) => r.data_type(),
+ _ => unreachable!(),
+ };
+
+ let len = pos.len();
+ if len == 0 {
+ let empty_run_ends = new_empty_run_ends(run_ends_type);
+ let empty_values = self.decoder.decode(tape, &[])?;
+ let data = ArrayDataBuilder::new(self.data_type.clone())
+ .len(0)
+ .add_child_data(empty_run_ends)
+ .add_child_data(empty_values);
+ // Safety:
+ // Valid by construction
+ return Ok(unsafe { data.build_unchecked() });
+ }
+
+ let flat_data = self.decoder.decode(tape, pos)?;
+
+ let mut run_ends: Vec<i64> = Vec::new();
+ let mut mutable = MutableArrayData::new(vec![&flat_data], false, len);
+
+ let mut run_start = 0;
+ for i in 1..len {
+ if !same_run(&flat_data, run_start, i) {
+ run_ends.push(i as i64);
+ mutable.extend(0, run_start, run_start + 1);
+ run_start = i;
+ }
+ }
+ run_ends.push(len as i64);
+ mutable.extend(0, run_start, run_start + 1);
+
+ let values_data = mutable.freeze();
+ let run_ends_data = build_run_ends_array(run_ends_type, run_ends)?;
+
+ let data = ArrayDataBuilder::new(self.data_type.clone())
+ .len(len)
+ .add_child_data(run_ends_data)
+ .add_child_data(values_data);
+
+ // Safety:
+ // Valid by construction
Review Comment:
What does valid by construction mean?
##########
arrow-json/src/reader/mod.rs:
##########
@@ -2857,4 +2860,187 @@ mod tests {
"Json error: whilst decoding field 'a': failed to parse \"a\" as
Int32".to_owned()
);
}
+
+ #[test]
+ fn test_read_run_end_encoded() {
+ let buf = r#"
+ {"a": "x"}
+ {"a": "x"}
+ {"a": "y"}
+ {"a": "y"}
+ {"a": "y"}
+ "#;
+
+ let ree_type = DataType::RunEndEncoded(
+ Arc::new(Field::new("run_ends", DataType::Int32, false)),
+ Arc::new(Field::new("values", DataType::Utf8, true)),
+ );
+ let schema = Arc::new(Schema::new(vec![Field::new("a", ree_type,
true)]));
+ let batches = do_read(buf, 1024, false, false, schema);
+ assert_eq!(batches.len(), 1);
+
+ let col = batches[0].column(0);
+ let run_array = col
Review Comment:
use `as_run` for more ergonomic downcasting
##########
arrow-json/src/reader/run_end_array.rs:
##########
@@ -0,0 +1,150 @@
+// 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::reader::tape::Tape;
+use crate::reader::{ArrayDecoder, DecoderContext};
+use arrow_array::Array;
+use arrow_data::transform::MutableArrayData;
+use arrow_data::{ArrayData, ArrayDataBuilder};
+use arrow_schema::{ArrowError, DataType};
+
+pub struct RunEndEncodedArrayDecoder {
+ data_type: DataType,
+ decoder: Box<dyn ArrayDecoder>,
+}
+
+impl RunEndEncodedArrayDecoder {
+ pub fn new(
+ ctx: &DecoderContext,
+ data_type: &DataType,
+ is_nullable: bool,
+ ) -> Result<Self, ArrowError> {
+ let values_field = match data_type {
+ DataType::RunEndEncoded(_, v) => v,
+ _ => unreachable!(),
+ };
+ let decoder = ctx.make_decoder(
+ values_field.data_type(),
+ values_field.is_nullable() || is_nullable,
+ )?;
+
+ Ok(Self {
+ data_type: data_type.clone(),
+ decoder,
+ })
+ }
+}
+
+impl ArrayDecoder for RunEndEncodedArrayDecoder {
+ fn decode(&mut self, tape: &Tape<'_>, pos: &[u32]) -> Result<ArrayData,
ArrowError> {
+ let run_ends_type = match &self.data_type {
+ DataType::RunEndEncoded(r, _) => r.data_type(),
+ _ => unreachable!(),
+ };
+
+ let len = pos.len();
+ if len == 0 {
+ let empty_run_ends = new_empty_run_ends(run_ends_type);
+ let empty_values = self.decoder.decode(tape, &[])?;
+ let data = ArrayDataBuilder::new(self.data_type.clone())
+ .len(0)
+ .add_child_data(empty_run_ends)
+ .add_child_data(empty_values);
+ // Safety:
+ // Valid by construction
+ return Ok(unsafe { data.build_unchecked() });
+ }
+
+ let flat_data = self.decoder.decode(tape, pos)?;
+
+ let mut run_ends: Vec<i64> = Vec::new();
+ let mut mutable = MutableArrayData::new(vec![&flat_data], false, len);
+
+ let mut run_start = 0;
+ for i in 1..len {
+ if !same_run(&flat_data, run_start, i) {
+ run_ends.push(i as i64);
+ mutable.extend(0, run_start, run_start + 1);
+ run_start = i;
+ }
+ }
+ run_ends.push(len as i64);
+ mutable.extend(0, run_start, run_start + 1);
+
+ let values_data = mutable.freeze();
+ let run_ends_data = build_run_ends_array(run_ends_type, run_ends)?;
+
+ let data = ArrayDataBuilder::new(self.data_type.clone())
+ .len(len)
+ .add_child_data(run_ends_data)
+ .add_child_data(values_data);
+
+ // Safety:
+ // Valid by construction
+ Ok(unsafe { data.build_unchecked() })
+ }
+}
+
+fn same_run(data: &ArrayData, i: usize, j: usize) -> bool {
+ let null_i = data.is_null(i);
+ let null_j = data.is_null(j);
+ if null_i != null_j {
+ return false;
+ }
+ if null_i {
+ return true;
+ }
+ data.slice(i, 1) == data.slice(j, 1)
+}
+
+fn build_run_ends_array(dt: &DataType, run_ends: Vec<i64>) ->
Result<ArrayData, ArrowError> {
Review Comment:
We could probably inline this if we make `RunEndEncodedArrayDecoder` generic
over its index type, instead of defaulting to `i64` and then trying to convert
after the fact
##########
arrow-json/src/reader/run_end_array.rs:
##########
@@ -0,0 +1,150 @@
+// 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::reader::tape::Tape;
+use crate::reader::{ArrayDecoder, DecoderContext};
+use arrow_array::Array;
+use arrow_data::transform::MutableArrayData;
+use arrow_data::{ArrayData, ArrayDataBuilder};
+use arrow_schema::{ArrowError, DataType};
+
+pub struct RunEndEncodedArrayDecoder {
+ data_type: DataType,
+ decoder: Box<dyn ArrayDecoder>,
+}
+
+impl RunEndEncodedArrayDecoder {
+ pub fn new(
+ ctx: &DecoderContext,
+ data_type: &DataType,
+ is_nullable: bool,
+ ) -> Result<Self, ArrowError> {
+ let values_field = match data_type {
+ DataType::RunEndEncoded(_, v) => v,
+ _ => unreachable!(),
+ };
+ let decoder = ctx.make_decoder(
+ values_field.data_type(),
+ values_field.is_nullable() || is_nullable,
+ )?;
+
+ Ok(Self {
+ data_type: data_type.clone(),
+ decoder,
+ })
+ }
+}
+
+impl ArrayDecoder for RunEndEncodedArrayDecoder {
+ fn decode(&mut self, tape: &Tape<'_>, pos: &[u32]) -> Result<ArrayData,
ArrowError> {
+ let run_ends_type = match &self.data_type {
+ DataType::RunEndEncoded(r, _) => r.data_type(),
+ _ => unreachable!(),
+ };
+
+ let len = pos.len();
+ if len == 0 {
+ let empty_run_ends = new_empty_run_ends(run_ends_type);
Review Comment:
We can use
[`new_empty_array`](https://docs.rs/arrow/latest/arrow/array/fn.new_empty_array.html)
Also not sure about calling decode here if len is zero; does that achieve
anything?
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