fix: calculate total seconds from interval fields for extract(epoch)

lemorage · lemorage · commit 9cd676e44afa · 2026-01-14T18:19:47.000+08:00
diff --git a/datafusion/functions/src/datetime/date_part.rs b/datafusion/functions/src/datetime/date_part.rs
@@ -26,13 +26,16 @@ use arrow::datatypes::DataType::{
     Date32, Date64, Duration, Interval, Time32, Time64, Timestamp,
 };
 use arrow::datatypes::TimeUnit::{Microsecond, Millisecond, Nanosecond, Second};
-use arrow::datatypes::{DataType, Field, FieldRef, TimeUnit};
+use arrow::datatypes::{
+    DataType, Field, FieldRef, IntervalUnit as ArrowIntervalUnit, TimeUnit,
+};
 use datafusion_common::types::{NativeType, logical_date};
 
 use datafusion_common::{
     Result, ScalarValue,
     cast::{
-        as_date32_array, as_date64_array, as_int32_array, as_time32_millisecond_array,
+        as_date32_array, as_date64_array, as_int32_array, as_interval_dt_array,
+        as_interval_mdn_array, as_interval_ym_array, as_time32_millisecond_array,
         as_time32_second_array, as_time64_microsecond_array, as_time64_nanosecond_array,
         as_timestamp_microsecond_array, as_timestamp_millisecond_array,
         as_timestamp_nanosecond_array, as_timestamp_second_array,
@@ -56,7 +59,7 @@ use datafusion_macros::user_doc;
     argument(
         name = "part",
         description = r#"Part of the date to return. The following date parts are supported:
-        
+
     - year
     - quarter (emits value in inclusive range [1, 4] based on which quartile of the year the date is in)
     - month
@@ -349,6 +352,7 @@ fn seconds(array: &dyn Array, unit: TimeUnit) -> Result<ArrayRef> {
 
 fn epoch(array: &dyn Array) -> Result<ArrayRef> {
     const SECONDS_IN_A_DAY: f64 = 86400_f64;
+    const DAYS_PER_MONTH: f64 = 30_f64;
 
     let f: Float64Array = match array.data_type() {
         Timestamp(Second, _) => as_timestamp_second_array(array)?.unary(|x| x as f64),
@@ -373,7 +377,19 @@ fn epoch(array: &dyn Array) -> Result<ArrayRef> {
         Time64(Nanosecond) => {
             as_time64_nanosecond_array(array)?.unary(|x| x as f64 / 1_000_000_000_f64)
         }
-        Interval(_) | Duration(_) => return seconds(array, Second),
+        Interval(ArrowIntervalUnit::YearMonth) => as_interval_ym_array(array)?
+            .unary(|x| x as f64 * DAYS_PER_MONTH * SECONDS_IN_A_DAY),
+        Interval(ArrowIntervalUnit::DayTime) => as_interval_dt_array(array)?.unary(|x| {
+            x.days as f64 * SECONDS_IN_A_DAY + x.milliseconds as f64 / 1_000_f64
+        }),
+        Interval(ArrowIntervalUnit::MonthDayNano) => {
+            as_interval_mdn_array(array)?.unary(|x| {
+                x.months as f64 * DAYS_PER_MONTH * SECONDS_IN_A_DAY
+                    + x.days as f64 * SECONDS_IN_A_DAY
+                    + x.nanoseconds as f64 / 1_000_000_000_f64
+            })
+        }
+        Duration(_) => return seconds(array, Second),
         d => return exec_err!("Cannot convert {d:?} to epoch"),
     };
     Ok(Arc::new(f))
diff --git a/datafusion/sqllogictest/test_files/datetime/date_part.slt b/datafusion/sqllogictest/test_files/datetime/date_part.slt
@@ -936,6 +936,27 @@ SELECT extract(second from arrow_cast(NULL, 'Interval(MonthDayNano)'))
 ----
 NULL
 
+# extract epoch from intervals
+query R
+SELECT extract(epoch from interval '15 minutes')
+----
+900
+
+query R
+SELECT extract(epoch from interval '1 hour')
+----
+3600
+
+query R
+SELECT extract(epoch from interval '1 day')
+----
+86400
+
+query R
+SELECT extract(epoch from interval '1 month')
+----
+2592000
+
 statement ok
 create table t (id int, i interval) as values
   (0, interval '5 months 1 day 10 nanoseconds'),
