datafusion_functions/string/
uuid.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 std::any::Any;
19use std::sync::Arc;
20
21use arrow::array::GenericStringBuilder;
22use arrow::datatypes::DataType;
23use arrow::datatypes::DataType::Utf8;
24use rand::Rng;
25use uuid::Uuid;
26
27use datafusion_common::{internal_err, Result};
28use datafusion_expr::{ColumnarValue, Documentation, Volatility};
29use datafusion_expr::{ScalarFunctionArgs, ScalarUDFImpl, Signature};
30use datafusion_macros::user_doc;
31
32#[user_doc(
33    doc_section(label = "String Functions"),
34    description = "Returns [`UUID v4`](https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random)) string value which is unique per row.",
35    syntax_example = "uuid()",
36    sql_example = r#"```sql
37> select uuid();
38+--------------------------------------+
39| uuid()                               |
40+--------------------------------------+
41| 6ec17ef8-1934-41cc-8d59-d0c8f9eea1f0 |
42+--------------------------------------+
43```"#
44)]
45#[derive(Debug)]
46pub struct UuidFunc {
47    signature: Signature,
48}
49
50impl Default for UuidFunc {
51    fn default() -> Self {
52        Self::new()
53    }
54}
55
56impl UuidFunc {
57    pub fn new() -> Self {
58        Self {
59            signature: Signature::exact(vec![], Volatility::Volatile),
60        }
61    }
62}
63
64impl ScalarUDFImpl for UuidFunc {
65    fn as_any(&self) -> &dyn Any {
66        self
67    }
68
69    fn name(&self) -> &str {
70        "uuid"
71    }
72
73    fn signature(&self) -> &Signature {
74        &self.signature
75    }
76
77    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
78        Ok(Utf8)
79    }
80
81    /// Prints random (v4) uuid values per row
82    /// uuid() = 'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'
83    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
84        if !args.args.is_empty() {
85            return internal_err!("{} function does not accept arguments", self.name());
86        }
87
88        // Generate random u128 values
89        let mut rng = rand::thread_rng();
90        let mut randoms = vec![0u128; args.number_rows];
91        rng.fill(&mut randoms[..]);
92
93        let mut builder = GenericStringBuilder::<i32>::with_capacity(
94            args.number_rows,
95            args.number_rows * 36,
96        );
97
98        let mut buffer = [0u8; 36];
99        for x in &mut randoms {
100            // From Uuid::new_v4(): Mask out the version and variant bits
101            *x = *x & 0xFFFFFFFFFFFF4FFFBFFFFFFFFFFFFFFF | 0x40008000000000000000;
102            let uuid = Uuid::from_u128(*x);
103            let fmt = uuid::fmt::Hyphenated::from_uuid(uuid);
104            builder.append_value(fmt.encode_lower(&mut buffer));
105        }
106
107        Ok(ColumnarValue::Array(Arc::new(builder.finish())))
108    }
109
110    fn documentation(&self) -> Option<&Documentation> {
111        self.doc()
112    }
113}
datafusion_functions/string/uuid.rs

datafusion_functions/string/
uuid.rs
