Support INTERVAL interpolation in MEDIAN aggregate

h2/src/docsrc/help/help.csv

@@ -3389,7 +3389,7 @@ MEDIAN( [ DISTINCT ] value ) [ FILTER ( WHERE expression ) ]
 ","
 The value separating the higher half of a values from the lower half.
 Returns the middle value or an interpolated value between two middle values if number of values is even.
-Interpolation is only supported for numeric, date, and time data types.
+Interpolation is only supported for numeric, date-time, and interval data types.
 NULL values are ignored in the calculation.
 If no rows are selected, the result is NULL.
 Aggregates are only allowed in select statements.

h2/src/main/org/h2/expression/AggregateDataMedian.java

@@ -9,6 +9,7 @@ import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.Arrays;
 
+import org.h2.api.IntervalQualifier;
 import org.h2.engine.Database;
 import org.h2.engine.Mode;
 import org.h2.engine.Session;
@@ -29,6 +30,7 @@ import org.h2.value.ValueDecimal;
 import org.h2.value.ValueDouble;
 import org.h2.value.ValueFloat;
 import org.h2.value.ValueInt;
+import org.h2.value.ValueInterval;
 import org.h2.value.ValueLong;
 import org.h2.value.ValueNull;
 import org.h2.value.ValueTime;
@@ -246,6 +248,22 @@ class AggregateDataMedian extends AggregateDataCollecting {
             return ValueTimestampTimeZone.fromDateValueAndNanos(DateTimeUtils.dateValueFromAbsoluteDay(dateSum / 2),
                     nanos, (short) (offset / 2));
         }
+        case Value.INTERVAL_YEAR:
+        case Value.INTERVAL_MONTH:
+        case Value.INTERVAL_DAY:
+        case Value.INTERVAL_HOUR:
+        case Value.INTERVAL_MINUTE:
+        case Value.INTERVAL_SECOND:
+        case Value.INTERVAL_YEAR_TO_MONTH:
+        case Value.INTERVAL_DAY_TO_HOUR:
+        case Value.INTERVAL_DAY_TO_MINUTE:
+        case Value.INTERVAL_DAY_TO_SECOND:
+        case Value.INTERVAL_HOUR_TO_MINUTE:
+        case Value.INTERVAL_HOUR_TO_SECOND:
+        case Value.INTERVAL_MINUTE_TO_SECOND:
+            return DateTimeUtils.intervalFromAbsolute(IntervalQualifier.valueOf(dataType - Value.INTERVAL_YEAR),
+                    DateTimeUtils.intervalToAbsolute((ValueInterval) v0)
+                    .add(DateTimeUtils.intervalToAbsolute((ValueInterval) v1)).shiftRight(1));
         default:
             // Just return first
             return v0.convertTo(dataType);

h2/src/test/org/h2/test/scripts/functions/aggregate/median.sql

@@ -504,6 +504,18 @@ select median(v) from test;
 drop table test;
 > ok
 
+create table test(v interval day to second);
+> ok
+
+insert into test values ('0 1'), ('0 2'), ('0 2'), ('0 2'), ('-0 1'), ('-0 1');
+> update count: 6
+
+select median (v) from test;
+>> INTERVAL '0 01:30:00' DAY TO SECOND
+
+drop table test;
+> ok
+
 -- with group by
 create table test(name varchar, value int);
 > ok