Omega359 commented on code in PR #14367: URL: https://github.com/apache/datafusion/pull/14367#discussion_r1940126117
########## datafusion/functions/src/hash/xxhash.rs: ########## @@ -0,0 +1,279 @@ +// 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, StringArray, Int32Array, Int64Array, UInt32Array, UInt64Array}; +use arrow::datatypes::DataType; +use datafusion_common::{Result, ScalarValue}; +use datafusion_expr::{ + ColumnarValue, Documentation, ScalarUDFImpl, Signature, Volatility, +}; +use twox_hash::{XxHash64, XxHash32}; +use datafusion_macros::user_doc; +use std::any::Any; +use std::hash::Hasher; +use datafusion_common::DataFusionError; +use std::sync::Arc; + +#[user_doc( + doc_section(label = "Hashing Functions"), + description = "Computes the XXHash64 hash of a binary string.", + syntax_example = "xxhash64(expression)", + sql_example = r#"```sql +> select xxhash64('foo'); ++-------------------------------------------+ +| xxhash64(Utf8("foo")) | ++-------------------------------------------+ +| <xxhash64_result> | ++-------------------------------------------+ +```"#, + standard_argument(name = "expression", prefix = "String") +)] +#[derive(Debug)] +pub struct XxHash64Func { + signature: Signature, +} + +impl Default for XxHash64Func { + fn default() -> Self { + Self::new() + } +} + +impl XxHash64Func { + pub fn new() -> Self { + use DataType::*; + Self { + signature: Signature::uniform( + 1, + vec![Utf8View, Utf8, LargeUtf8, Binary, LargeBinary], + Volatility::Immutable, + ), + } + } + + pub fn hash_scalar(&self, value: &ColumnarValue) -> Result<String> { + let value_str = to_string_from_scalar(value)?; + hash_value(&value_str, XxHash64::default(), HashType::U64) + } +} + +impl ScalarUDFImpl for XxHash64Func { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "xxhash64" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> { + Ok(DataType::Utf8) + } + + fn invoke_batch( + &self, + args: &[ColumnarValue], + _number_rows: usize, + ) -> Result<ColumnarValue> { + let input_data = &args[0]; + + let result = match input_data { + ColumnarValue::Array(array) => { + let hash_results = process_array(array, XxHash64::default(), HashType::U64)?; + let hash_array = StringArray::from(hash_results); + Arc::new(hash_array) as Arc<dyn Array> + }, + ColumnarValue::Scalar(scalar) => { + let hash_result = self.hash_scalar(&ColumnarValue::Scalar(scalar.clone()))?; + let hash_array = StringArray::from(vec![hash_result]); + Arc::new(hash_array) as Arc<dyn Array> + } + }; + + Ok(ColumnarValue::Array(result)) + } + + fn documentation(&self) -> Option<&Documentation> { + self.doc() + } +} + +#[user_doc( + doc_section(label = "Hashing Functions"), + description = "Computes the XXHash32 hash of a binary string.", + syntax_example = "xxhash32(expression)", + sql_example = r#"```sql +> select xxhash32('foo'); ++-------------------------------------------+ +| xxhash32(Utf8("foo")) | ++-------------------------------------------+ +| <xxhash32_result> | ++-------------------------------------------+ +```"#, + standard_argument(name = "expression", prefix = "String") +)] +#[derive(Debug)] +pub struct XxHash32Func { + signature: Signature, +} + +impl Default for XxHash32Func { + fn default() -> Self { + Self::new() + } +} + +impl XxHash32Func { + pub fn new() -> Self { + use DataType::*; + Self { + signature: Signature::uniform( + 1, + vec![Utf8View, Utf8, LargeUtf8, Binary, LargeBinary], + Volatility::Immutable, + ), + } + } + + pub fn hash_scalar(&self, value: &ColumnarValue) -> Result<String> { + let value_str = to_string_from_scalar(value)?; + hash_value(&value_str, XxHash32::default(), HashType::U32) + } +} + +impl ScalarUDFImpl for XxHash32Func { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "xxhash32" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> { + Ok(DataType::Utf8) + } + + fn invoke_batch( + &self, + args: &[ColumnarValue], + _number_rows: usize, + ) -> Result<ColumnarValue> { + let input_data = &args[0]; + + let result = match input_data { + ColumnarValue::Array(array) => { + let hash_results = process_array(array, XxHash32::default(), HashType::U32)?; + let hash_array = StringArray::from(hash_results); + Arc::new(hash_array) as Arc<dyn Array> + }, + ColumnarValue::Scalar(scalar) => { + let hash_result = self.hash_scalar(&ColumnarValue::Scalar(scalar.clone()))?; + let hash_array = StringArray::from(vec![hash_result]); + Arc::new(hash_array) as Arc<dyn Array> + } + }; + + Ok(ColumnarValue::Array(result)) + } + + fn documentation(&self) -> Option<&Documentation> { + self.doc() + } +} + +// Helper functions + +fn to_string_from_scalar(value: &ColumnarValue) -> Result<String> { + match value { + ColumnarValue::Scalar(scalar) => match scalar { + ScalarValue::Utf8(Some(v)) => Ok(v.clone()), + ScalarValue::Int32(Some(v)) => Ok(v.to_string()), + ScalarValue::Int64(Some(v)) => Ok(v.to_string()), + ScalarValue::UInt32(Some(v)) => Ok(v.to_string()), + ScalarValue::UInt64(Some(v)) => Ok(v.to_string()), + _ => Err(DataFusionError::Internal("Unsupported scalar type".to_string())), + }, + _ => Err(DataFusionError::Internal("Expected a scalar value".to_string())), + } +} + +#[derive(Clone)] +pub enum HashType { + U32, + U64, +} + +fn hash_value<T: Hasher>(value_str: &str, mut hasher: T, hash_type: HashType) -> Result<String, DataFusionError> { + hasher.write(value_str.as_bytes()); + let hash = hasher.finish(); + match hash_type { + HashType::U32 => { + let hash_u32 = hash as u32; + Ok(hex::encode(hash_u32.to_be_bytes())) + }, + HashType::U64 => { + let hash_u64 = hash as u64; + Ok(hex::encode(hash_u64.to_be_bytes())) + }, + } +} + +fn process_array<T: Hasher>(array: &dyn Array, mut hasher: T, hash_type: HashType) -> Result<Vec<String>> { + let mut hash_results: Vec<String> = Vec::with_capacity(array.len()); + for i in 0..array.len() { Review Comment: Instead of downcasting the array for every single element in it see if you can do it once up front. -- This is an automated message from the Apache Git Service. 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