datafusion_functions/crypto/
md5.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use arrow::{array::StringViewArray, datatypes::DataType};
19use datafusion_common::{
20    Result, ScalarValue,
21    cast::as_binary_array,
22    internal_err,
23    types::{logical_binary, logical_string},
24    utils::take_function_args,
25};
26use datafusion_expr::{
27    ColumnarValue, Documentation, ScalarFunctionArgs, ScalarUDFImpl, Signature,
28    TypeSignature, Volatility,
29};
30use datafusion_expr_common::signature::{Coercion, TypeSignatureClass};
31use datafusion_macros::user_doc;
32use std::sync::Arc;
33
34use crate::crypto::basic::{DigestAlgorithm, digest_process};
35
36#[user_doc(
37    doc_section(label = "Hashing Functions"),
38    description = "Computes an MD5 128-bit checksum for a string expression.",
39    syntax_example = "md5(expression)",
40    sql_example = r#"```sql
41> select md5('foo');
42+----------------------------------+
43| md5(Utf8("foo"))                 |
44+----------------------------------+
45| acbd18db4cc2f85cedef654fccc4a4d8 |
46+----------------------------------+
47```"#,
48    standard_argument(name = "expression", prefix = "String")
49)]
50#[derive(Debug, PartialEq, Eq, Hash)]
51pub struct Md5Func {
52    signature: Signature,
53}
54
55impl Default for Md5Func {
56    fn default() -> Self {
57        Self::new()
58    }
59}
60
61impl Md5Func {
62    pub fn new() -> Self {
63        Self {
64            signature: Signature::one_of(
65                vec![
66                    TypeSignature::Coercible(vec![Coercion::new_exact(
67                        TypeSignatureClass::Native(logical_string()),
68                    )]),
69                    TypeSignature::Coercible(vec![Coercion::new_exact(
70                        TypeSignatureClass::Native(logical_binary()),
71                    )]),
72                ],
73                Volatility::Immutable,
74            ),
75        }
76    }
77}
78
79impl ScalarUDFImpl for Md5Func {
80    fn name(&self) -> &str {
81        "md5"
82    }
83
84    fn signature(&self) -> &Signature {
85        &self.signature
86    }
87
88    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
89        Ok(DataType::Utf8View)
90    }
91
92    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
93        md5(&args.args)
94    }
95
96    fn documentation(&self) -> Option<&Documentation> {
97        self.doc()
98    }
99}
100
101/// Hex encoding lookup table for fast byte-to-hex conversion
102const HEX_CHARS_LOWER: &[u8; 16] = b"0123456789abcdef";
103
104/// Fast hex encoding using a lookup table instead of format strings.
105/// This is significantly faster than using `write!("{:02x}")` for each byte.
106#[inline]
107fn hex_encode(data: impl AsRef<[u8]>) -> String {
108    let bytes = data.as_ref();
109    let mut s = String::with_capacity(bytes.len() * 2);
110    for &b in bytes {
111        s.push(HEX_CHARS_LOWER[(b >> 4) as usize] as char);
112        s.push(HEX_CHARS_LOWER[(b & 0x0f) as usize] as char);
113    }
114    s
115}
116
117fn md5(args: &[ColumnarValue]) -> Result<ColumnarValue> {
118    let [data] = take_function_args("md5", args)?;
119    let value = digest_process(data, DigestAlgorithm::Md5)?;
120
121    // md5 requires special handling because of its unique utf8view return type
122    Ok(match value {
123        ColumnarValue::Array(array) => {
124            let binary_array = as_binary_array(&array)?;
125            let string_array: StringViewArray =
126                binary_array.iter().map(|opt| opt.map(hex_encode)).collect();
127            ColumnarValue::Array(Arc::new(string_array))
128        }
129        ColumnarValue::Scalar(ScalarValue::Binary(opt)) => {
130            ColumnarValue::Scalar(ScalarValue::Utf8View(opt.map(hex_encode)))
131        }
132        _ => return internal_err!("Impossibly got invalid results from digest"),
133    })
134}
datafusion_functions/crypto/md5.rs

datafusion_functions/crypto/
md5.rs
