Feat: Make current_date aware of execution timezone. (#18034)

* Feat: Make current_date aware of execution timezone.

* CI Fixes: Rectify assertion error of slt and update scalar_functions.md

* CI Fixes: Comment out flaky test involving now().

* CI Fixes: Resolve slt error.

* Feat: Add helper function to calculate current_date and fix tests.

* Chore: Refactor timezone conversion logic.

Author: codetyri0n

datafusion/functions/src/datetime/current_date.rs

@@ -17,9 +17,10 @@
 
 use std::any::Any;
 
+use arrow::array::timezone::Tz;
 use arrow::datatypes::DataType;
 use arrow::datatypes::DataType::Date32;
-use chrono::{Datelike, NaiveDate};
+use chrono::{Datelike, NaiveDate, TimeZone};
 
 use datafusion_common::{internal_err, Result, ScalarValue};
 use datafusion_expr::simplify::{ExprSimplifyResult, SimplifyInfo};
@@ -31,7 +32,7 @@ use datafusion_macros::user_doc;
 #[user_doc(
     doc_section(label = "Time and Date Functions"),
     description = r#"
-Returns the current UTC date.
+Returns the current date in the session time zone.
 
 The `current_date()` return value is determined at query time and will return the same date, no matter when in the query plan the function executes.
 "#,
@@ -100,14 +101,21 @@ impl ScalarUDFImpl for CurrentDateFunc {
         info: &dyn SimplifyInfo,
     ) -> Result<ExprSimplifyResult> {
         let now_ts = info.execution_props().query_execution_start_time;
-        let days = Some(
-            now_ts.num_days_from_ce()
-                - NaiveDate::from_ymd_opt(1970, 1, 1)
-                    .unwrap()
-                    .num_days_from_ce(),
-        );
+
+        // Get timezone from config and convert to local time
+        let days = info
+            .execution_props()
+            .config_options()
+            .and_then(|config| config.execution.time_zone.parse::<Tz>().ok())
+            .map_or_else(
+                || datetime_to_days(&now_ts),
+                |tz| {
+                    let local_now = tz.from_utc_datetime(&now_ts.naive_utc());
+                    datetime_to_days(&local_now)
+                },
+            );
         Ok(ExprSimplifyResult::Simplified(Expr::Literal(
-            ScalarValue::Date32(days),
+            ScalarValue::Date32(Some(days)),
             None,
         )))
     }
@@ -116,3 +124,11 @@ impl ScalarUDFImpl for CurrentDateFunc {
         self.doc()
     }
 }
+
+/// Converts a DateTime to the number of days since Unix epoch (1970-01-01)
+fn datetime_to_days<T: Datelike>(dt: &T) -> i32 {
+    dt.num_days_from_ce()
+        - NaiveDate::from_ymd_opt(1970, 1, 1)
+            .unwrap()
+            .num_days_from_ce()
+}

datafusion/sqllogictest/test_files/current_date_timezone.slt

@@ -0,0 +1,80 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+
+#   http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+##########
+## current_date with timezone tests
+##########
+
+# Test 1: Verify current_date is consistent within the same query (default UTC)
+query B
+SELECT current_date() = current_date();
+----
+true
+
+# Test 2: Verify alias 'today' works the same as current_date
+query B
+SELECT current_date() = today();
+----
+true
+
+# Test 3: Set timezone to +05:00 and verify current_date is still stable
+statement ok
+SET datafusion.execution.time_zone = '+05:00';
+
+query B
+SELECT current_date() = current_date();
+----
+true
+
+#Test 4: Verify current_date matches cast(now() as date) in the same timezone
+query B
+SELECT current_date() = cast(now() as date);
+----
+true
+
+# Test 5: Test with negative offset timezone
+statement ok
+SET datafusion.execution.time_zone = '-08:00';
+
+query B
+SELECT current_date() = today();
+----
+true
+
+# Test 6: Test with named timezone (America/New_York)
+statement ok
+SET datafusion.execution.time_zone = 'America/New_York';
+
+query B
+SELECT current_date() = current_date();
+----
+true
+
+# Test 7: Verify date type is preserved
+query T
+SELECT arrow_typeof(current_date());
+----
+Date32
+
+# Test 8: Reset to UTC
+statement ok
+SET datafusion.execution.time_zone = '+00:00';
+
+query B
+SELECT current_date() = today();
+----
+true

docs/source/user-guide/sql/scalar_functions.md

@@ -2403,7 +2403,7 @@ Additional examples can be found [here](https://github.com/apache/datafusion/blo
 
 ### `current_date`
 
-Returns the current UTC date.
+Returns the current date in the session time zone.
 
 The `current_date()` return value is determined at query time and will return the same date, no matter when in the query plan the function executes.