Remove call to Calendar for truncate the date to 'WEEK'

h2/src/main/org/h2/util/DateTimeFunctions.java

@@ -445,14 +445,11 @@ public final class DateTimeFunctions {
 
         case WEEK:
 
-            // Use Calendar to retrieve the first day of the week and convert
-            // the date to a dateValue
-            Date currentDate = DateTimeUtils.convertDateValueToDate(dateValue);
-            Calendar calendar = Calendar.getInstance();
-            calendar.setTime(currentDate);
-            calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
-            ValueTimestamp valueTimestamp = ValueTimestamp.fromMillis(calendar.getTimeInMillis());
-            dateValue = valueTimestamp.getDateValue();
+            long absoluteDay = DateTimeUtils.absoluteDayFromDateValue(dateValue);
+            int dayOfWeek = DateTimeUtils.getDayOfWeekFromAbsolute(absoluteDay, 1);
+            if (dayOfWeek != 1) {
+                dateValue = DateTimeUtils.dateValueFromAbsoluteDay(absoluteDay - dayOfWeek + 1);
+            }
             timeNanos = 0l;
             break;
 

h2/src/main/org/h2/util/DateTimeUtils.java

@@ -728,7 +728,7 @@ public class DateTimeUtils {
         return getDayOfWeekFromAbsolute(absoluteDayFromDateValue(dateValue), firstDayOfWeek);
     }
 
-    private static int getDayOfWeekFromAbsolute(long absoluteValue, int firstDayOfWeek) {
+    public static int getDayOfWeekFromAbsolute(long absoluteValue, int firstDayOfWeek) {
         return absoluteValue >= 0 ? (int) ((absoluteValue - firstDayOfWeek + 11) % 7) + 1
                 : (int) ((absoluteValue - firstDayOfWeek - 2) % 7) + 7;
     }