datafusion_spark/function/datetime/
trunc.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::sync::Arc;
19
20use arrow::datatypes::{DataType, Field, FieldRef, TimeUnit};
21use datafusion_common::types::{NativeType, logical_date, logical_string};
22use datafusion_common::utils::take_function_args;
23use datafusion_common::{Result, ScalarValue, internal_err, plan_err};
24use datafusion_expr::expr::ScalarFunction;
25use datafusion_expr::simplify::{ExprSimplifyResult, SimplifyContext};
26use datafusion_expr::{
27    Coercion, ColumnarValue, Expr, ExprSchemable, ReturnFieldArgs, ScalarFunctionArgs,
28    ScalarUDFImpl, Signature, TypeSignatureClass, Volatility,
29};
30
31/// Spark trunc supports date inputs only and extra format aliases.
32/// Also spark trunc's argument order is (date, format).
33/// <https://spark.apache.org/docs/latest/api/sql/index.html#trunc>
34#[derive(Debug, PartialEq, Eq, Hash)]
35pub struct SparkTrunc {
36    signature: Signature,
37}
38
39impl Default for SparkTrunc {
40    fn default() -> Self {
41        Self::new()
42    }
43}
44
45impl SparkTrunc {
46    pub fn new() -> Self {
47        Self {
48            signature: Signature::coercible(
49                vec![
50                    Coercion::new_implicit(
51                        TypeSignatureClass::Native(logical_date()),
52                        vec![TypeSignatureClass::Native(logical_string())],
53                        NativeType::Date,
54                    ),
55                    Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
56                ],
57                Volatility::Immutable,
58            ),
59        }
60    }
61}
62
63impl ScalarUDFImpl for SparkTrunc {
64    fn name(&self) -> &str {
65        "trunc"
66    }
67
68    fn signature(&self) -> &Signature {
69        &self.signature
70    }
71
72    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
73        internal_err!("return_field_from_args should be used instead")
74    }
75
76    fn return_field_from_args(&self, args: ReturnFieldArgs) -> Result<FieldRef> {
77        let nullable = args.arg_fields.iter().any(|f| f.is_nullable());
78
79        Ok(Arc::new(Field::new(
80            self.name(),
81            args.arg_fields[0].data_type().clone(),
82            nullable,
83        )))
84    }
85
86    fn invoke_with_args(&self, _args: ScalarFunctionArgs) -> Result<ColumnarValue> {
87        internal_err!("spark trunc should have been simplified to standard date_trunc")
88    }
89
90    fn simplify(
91        &self,
92        args: Vec<Expr>,
93        info: &SimplifyContext,
94    ) -> Result<ExprSimplifyResult> {
95        let [dt_expr, fmt_expr] = take_function_args(self.name(), args)?;
96
97        let fmt = match fmt_expr.as_literal() {
98            Some(ScalarValue::Utf8(Some(v)))
99            | Some(ScalarValue::Utf8View(Some(v)))
100            | Some(ScalarValue::LargeUtf8(Some(v))) => v.to_lowercase(),
101            _ => {
102                return plan_err!(
103                    "Second argument of `TRUNC` must be non-null scalar Utf8"
104                );
105            }
106        };
107
108        // Map Spark-specific fmt aliases to datafusion ones
109        let fmt = match fmt.as_str() {
110            "yy" | "yyyy" => "year",
111            "mm" | "mon" => "month",
112            "year" | "month" | "day" | "week" | "quarter" => fmt.as_str(),
113            _ => {
114                return plan_err!(
115                    "The format argument of `TRUNC` must be one of: year, yy, yyyy, month, mm, mon, day, week, quarter."
116                );
117            }
118        };
119        let return_type = dt_expr.get_type(info.schema())?;
120
121        let fmt_expr = Expr::Literal(ScalarValue::new_utf8(fmt), None);
122
123        // Spark uses Dates so we need to cast to timestamp and back to work with datafusion's date_trunc
124        Ok(ExprSimplifyResult::Simplified(
125            Expr::ScalarFunction(ScalarFunction::new_udf(
126                datafusion_functions::datetime::date_trunc(),
127                vec![
128                    fmt_expr,
129                    dt_expr.cast_to(
130                        &DataType::Timestamp(TimeUnit::Nanosecond, None),
131                        info.schema(),
132                    )?,
133                ],
134            ))
135            .cast_to(&return_type, info.schema())?,
136        ))
137    }
138}
datafusion_spark/function/datetime/trunc.rs

datafusion_spark/function/datetime/
trunc.rs
