datafusion_spark/function/datetime/
date_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_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 date_trunc supports extra format aliases.
32/// It also handles timestamps with timezones by converting to session timezone first.
33/// <https://spark.apache.org/docs/latest/api/sql/index.html#date_trunc>
34#[derive(Debug, PartialEq, Eq, Hash)]
35pub struct SparkDateTrunc {
36    signature: Signature,
37}
38
39impl Default for SparkDateTrunc {
40    fn default() -> Self {
41        Self::new()
42    }
43}
44
45impl SparkDateTrunc {
46    pub fn new() -> Self {
47        Self {
48            signature: Signature::coercible(
49                vec![
50                    Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
51                    Coercion::new_implicit(
52                        TypeSignatureClass::Timestamp,
53                        vec![TypeSignatureClass::Native(logical_string())],
54                        NativeType::Timestamp(TimeUnit::Microsecond, None),
55                    ),
56                ],
57                Volatility::Immutable,
58            ),
59        }
60    }
61}
62
63impl ScalarUDFImpl for SparkDateTrunc {
64    fn name(&self) -> &str {
65        "date_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[1].data_type().clone(),
82            nullable,
83        )))
84    }
85
86    fn invoke_with_args(&self, _args: ScalarFunctionArgs) -> Result<ColumnarValue> {
87        internal_err!(
88            "spark date_trunc should have been simplified to standard date_trunc"
89        )
90    }
91
92    fn simplify(
93        &self,
94        args: Vec<Expr>,
95        info: &SimplifyContext,
96    ) -> Result<ExprSimplifyResult> {
97        let [fmt_expr, ts_expr] = take_function_args(self.name(), args)?;
98
99        let fmt = match fmt_expr.as_literal() {
100            Some(ScalarValue::Utf8(Some(v)))
101            | Some(ScalarValue::Utf8View(Some(v)))
102            | Some(ScalarValue::LargeUtf8(Some(v))) => v.to_lowercase(),
103            _ => {
104                return plan_err!(
105                    "First argument of `DATE_TRUNC` must be non-null scalar Utf8"
106                );
107            }
108        };
109
110        // Map Spark-specific fmt aliases to datafusion ones
111        let fmt = match fmt.as_str() {
112            "yy" | "yyyy" => "year",
113            "mm" | "mon" => "month",
114            "dd" => "day",
115            other => other,
116        };
117
118        let session_tz = info.config_options().execution.time_zone.clone();
119        let ts_type = ts_expr.get_type(info.schema())?;
120
121        // Spark interprets timestamps in the session timezone before truncating,
122        // then returns a timestamp at microsecond precision.
123        // See: https://github.com/apache/spark/blob/f310f4fcc95580a6824bc7d22b76006f79b8804a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/DateTimeUtils.scala#L492
124        //
125        // For sub-second truncations (second, millisecond, microsecond), timezone
126        // adjustment is unnecessary since timezone offsets are whole seconds.
127        let ts_expr = match (&ts_type, fmt) {
128            // Sub-second truncations don't need timezone adjustment
129            (_, "second" | "millisecond" | "microsecond") => ts_expr,
130
131            // convert to session timezone, strip timezone and convert back to original timezone
132            (DataType::Timestamp(unit, tz), _) => {
133                let ts_expr = match &session_tz {
134                    Some(session_tz) => ts_expr.cast_to(
135                        &DataType::Timestamp(
136                            TimeUnit::Microsecond,
137                            Some(Arc::from(session_tz.as_str())),
138                        ),
139                        info.schema(),
140                    )?,
141                    None => ts_expr,
142                };
143                Expr::ScalarFunction(ScalarFunction::new_udf(
144                    datafusion_functions::datetime::to_local_time(),
145                    vec![ts_expr],
146                ))
147                .cast_to(&DataType::Timestamp(*unit, tz.clone()), info.schema())?
148            }
149
150            _ => {
151                return plan_err!(
152                    "Second argument of `DATE_TRUNC` must be Timestamp, got {}",
153                    ts_type
154                );
155            }
156        };
157
158        let fmt_expr = Expr::Literal(ScalarValue::new_utf8(fmt), None);
159
160        Ok(ExprSimplifyResult::Simplified(Expr::ScalarFunction(
161            ScalarFunction::new_udf(
162                datafusion_functions::datetime::date_trunc(),
163                vec![fmt_expr, ts_expr],
164            ),
165        )))
166    }
167}
datafusion_spark/function/datetime/date_trunc.rs

datafusion_spark/function/datetime/
date_trunc.rs
