feat: support_cast_date_timestamp

native/spark-expr/src/conversion_funcs/cast.rs

@@ -21,7 +21,7 @@ use crate::{EvalMode, SparkError, SparkResult};
 use arrow::array::builder::StringBuilder;
 use arrow::array::{
     BooleanBuilder, Decimal128Builder, DictionaryArray, GenericByteArray, ListArray,
-    PrimitiveBuilder, StringArray, StructArray,
+    PrimitiveBuilder, StringArray, StructArray, TimestampMicrosecondBuilder,
 };
 use arrow::compute::can_cast_types;
 use arrow::datatypes::{
@@ -1100,6 +1100,7 @@ fn cast_array(
             Ok(cast_with_options(&array, to_type, &CAST_OPTIONS)?)
         }
         (Binary, Utf8) => Ok(cast_binary_to_string::<i32>(&array, cast_options)?),
+        (Date32, Timestamp(_, tz)) => Ok(cast_date_to_timestamp(&array, cast_options, tz)?),
         _ if cast_options.is_adapting_schema
             || is_datafusion_spark_compatible(from_type, to_type) =>
         {
@@ -1118,6 +1119,50 @@ fn cast_array(
     Ok(spark_cast_postprocess(cast_result?, from_type, to_type))
 }
 
+fn cast_date_to_timestamp(
+    array_ref: &ArrayRef,
+    cast_options: &SparkCastOptions,
+    target_tz: &Option<Arc<str>>,
+) -> SparkResult<ArrayRef> {
+    let tz_str = if cast_options.timezone.is_empty() {
+        "UTC"
+    } else {
+        cast_options.timezone.as_str()
+    };
+    // safe to unwrap since we are falling back to UTC above
+    let tz = timezone::Tz::from_str(tz_str)?;
+    let epoch = NaiveDate::from_ymd_opt(1970, 1, 1).unwrap();
+    let date_array = array_ref.as_primitive::<Date32Type>();
+
+    let mut builder = TimestampMicrosecondBuilder::with_capacity(date_array.len());
+
+    for date in date_array.iter() {
+        match date {
+            Some(date) => {
+                // safe to unwrap since chrono's range ( 262,143 yrs) is higher than
+                // number of years possible with days as i32 (~ 6 mil yrs)
+                // convert date in session timezone to timestamp in UTC
+                let naive_date = epoch + chrono::Duration::days(date as i64);
+                let local_midnight = naive_date.and_hms_opt(0, 0, 0).unwrap();
+                let local_midnight_in_microsec = tz
+                    .from_local_datetime(&local_midnight)
+                    // return earliest possible time (edge case with spring / fall DST changes)
+                    .earliest()
+                    .map(|dt| dt.timestamp_micros())
+                    // in case there is an issue with DST and returns None , we fall back to UTC
+                    .unwrap_or((date as i64) * 86_400 * 1_000_000);
+                builder.append_value(local_midnight_in_microsec);
+            }
+            None => {
+                builder.append_null();
+            }
+        }
+    }
+    Ok(Arc::new(
+        builder.finish().with_timezone_opt(target_tz.clone()),
+    ))
+}
+
 fn cast_string_to_float(
     array: &ArrayRef,
     to_type: &DataType,

spark/src/main/scala/org/apache/comet/expressions/CometCast.scala

@@ -168,6 +168,7 @@ object CometCast extends CometExpressionSerde[Cast] with CometExprShim {
           }
         }
         Compatible()
+      case (DataTypes.DateType, toType) => canCastFromDate(toType)
       case _ => unsupported(fromType, toType)
     }
   }
@@ -344,6 +345,12 @@ object CometCast extends CometExpressionSerde[Cast] with CometExprShim {
     case _ => Unsupported(Some(s"Cast from DecimalType to $toType is not supported"))
   }
 
+  private def canCastFromDate(toType: DataType): SupportLevel = toType match {
+    case DataTypes.TimestampType =>
+      Compatible()
+    case _ => Unsupported(Some(s"Cast from DateType to $toType is not supported"))
+  }
+
   private def unsupported(fromType: DataType, toType: DataType): Unsupported = {
     Unsupported(Some(s"Cast from $fromType to $toType is not supported"))
   }

spark/src/test/scala/org/apache/comet/CometCastSuite.scala

@@ -989,8 +989,7 @@ class CometCastSuite extends CometTestBase with AdaptiveSparkPlanHelper {
     castTest(generateDates(), DataTypes.StringType)
   }
 
-  ignore("cast DateType to TimestampType") {
-    // Arrow error: Cast error: Casting from Date32 to Timestamp(Microsecond, Some("UTC")) not supported
+  test("cast DateType to TimestampType") {
     castTest(generateDates(), DataTypes.TimestampType)
   }