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::any::Any;
19use std::sync::Arc;
20
21use arrow::datatypes::{DataType, Field, FieldRef, TimeUnit};
22use datafusion_common::types::{NativeType, logical_string};
23use datafusion_common::utils::take_function_args;
24use datafusion_common::{Result, ScalarValue, internal_err, plan_err};
25use datafusion_expr::expr::ScalarFunction;
26use datafusion_expr::simplify::{ExprSimplifyResult, SimplifyContext};
27use datafusion_expr::{
28    Coercion, ColumnarValue, Expr, ExprSchemable, ReturnFieldArgs, ScalarFunctionArgs,
29    ScalarUDFImpl, Signature, TypeSignatureClass, Volatility,
30};
31
32/// Spark date_trunc supports extra format aliases.
33/// It also handles timestamps with timezones by converting to session timezone first.
34/// <https://spark.apache.org/docs/latest/api/sql/index.html#date_trunc>
35#[derive(Debug, PartialEq, Eq, Hash)]
36pub struct SparkDateTrunc {
37    signature: Signature,
38}
39
40impl Default for SparkDateTrunc {
41    fn default() -> Self {
42        Self::new()
43    }
44}
45
46impl SparkDateTrunc {
47    pub fn new() -> Self {
48        Self {
49            signature: Signature::coercible(
50                vec![
51                    Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
52                    Coercion::new_implicit(
53                        TypeSignatureClass::Timestamp,
54                        vec![TypeSignatureClass::Native(logical_string())],
55                        NativeType::Timestamp(TimeUnit::Microsecond, None),
56                    ),
57                ],
58                Volatility::Immutable,
59            ),
60        }
61    }
62}
63
64impl ScalarUDFImpl for SparkDateTrunc {
65    fn as_any(&self) -> &dyn Any {
66        self
67    }
68
69    fn name(&self) -> &str {
70        "date_trunc"
71    }
72
73    fn signature(&self) -> &Signature {
74        &self.signature
75    }
76
77    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
78        internal_err!("return_field_from_args should be used instead")
79    }
80
81    fn return_field_from_args(&self, args: ReturnFieldArgs) -> Result<FieldRef> {
82        let nullable = args.arg_fields.iter().any(|f| f.is_nullable());
83
84        Ok(Arc::new(Field::new(
85            self.name(),
86            args.arg_fields[1].data_type().clone(),
87            nullable,
88        )))
89    }
90
91    fn invoke_with_args(&self, _args: ScalarFunctionArgs) -> Result<ColumnarValue> {
92        internal_err!(
93            "spark date_trunc should have been simplified to standard date_trunc"
94        )
95    }
96
97    fn simplify(
98        &self,
99        args: Vec<Expr>,
100        info: &SimplifyContext,
101    ) -> Result<ExprSimplifyResult> {
102        let [fmt_expr, ts_expr] = take_function_args(self.name(), args)?;
103
104        let fmt = match fmt_expr.as_literal() {
105            Some(ScalarValue::Utf8(Some(v)))
106            | Some(ScalarValue::Utf8View(Some(v)))
107            | Some(ScalarValue::LargeUtf8(Some(v))) => v.to_lowercase(),
108            _ => {
109                return plan_err!(
110                    "First argument of `DATE_TRUNC` must be non-null scalar Utf8"
111                );
112            }
113        };
114
115        // Map Spark-specific fmt aliases to datafusion ones
116        let fmt = match fmt.as_str() {
117            "yy" | "yyyy" => "year",
118            "mm" | "mon" => "month",
119            "dd" => "day",
120            other => other,
121        };
122
123        let session_tz = info.config_options().execution.time_zone.clone();
124        let ts_type = ts_expr.get_type(info.schema())?;
125
126        // Spark interprets timestamps in the session timezone before truncating,
127        // then returns a timestamp at microsecond precision.
128        // See: https://github.com/apache/spark/blob/f310f4fcc95580a6824bc7d22b76006f79b8804a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/DateTimeUtils.scala#L492
129        //
130        // For sub-second truncations (second, millisecond, microsecond), timezone
131        // adjustment is unnecessary since timezone offsets are whole seconds.
132        let ts_expr = match (&ts_type, fmt) {
133            // Sub-second truncations don't need timezone adjustment
134            (_, "second" | "millisecond" | "microsecond") => ts_expr,
135
136            // convert to session timezone, strip timezone and convert back to original timezone
137            (DataType::Timestamp(unit, tz), _) => {
138                let ts_expr = match &session_tz {
139                    Some(session_tz) => ts_expr.cast_to(
140                        &DataType::Timestamp(
141                            TimeUnit::Microsecond,
142                            Some(Arc::from(session_tz.as_str())),
143                        ),
144                        info.schema(),
145                    )?,
146                    None => ts_expr,
147                };
148                Expr::ScalarFunction(ScalarFunction::new_udf(
149                    datafusion_functions::datetime::to_local_time(),
150                    vec![ts_expr],
151                ))
152                .cast_to(&DataType::Timestamp(*unit, tz.clone()), info.schema())?
153            }
154
155            _ => {
156                return plan_err!(
157                    "Second argument of `DATE_TRUNC` must be Timestamp, got {}",
158                    ts_type
159                );
160            }
161        };
162
163        let fmt_expr = Expr::Literal(ScalarValue::new_utf8(fmt), None);
164
165        Ok(ExprSimplifyResult::Simplified(Expr::ScalarFunction(
166            ScalarFunction::new_udf(
167                datafusion_functions::datetime::date_trunc(),
168                vec![fmt_expr, ts_expr],
169            ),
170        )))
171    }
172}
datafusion_spark/function/datetime/date_trunc.rs

datafusion_spark/function/datetime/
date_trunc.rs
