Add support of iso 8601 date string to date and time

- add an IT for date time comparison with iso 8601 formatted literal

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

core/src/main/java/org/opensearch/sql/data/model/ExprDateValue.java

@@ -8,6 +8,7 @@
 import com.google.common.base.Objects;
 import java.time.Instant;
 import java.time.LocalDate;
+import java.time.LocalDateTime;
 import java.time.LocalTime;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
@@ -32,7 +33,14 @@ public class ExprDateValue extends AbstractExprValue {
    */
   public ExprDateValue(String date) {
     try {
-      this.date = LocalDate.parse(date, DateTimeFormatters.DATE_TIMESTAMP_FORMATTER);
+      LocalDateTime ldt;
+      try {
+        ldt = LocalDateTime.parse(date, DateTimeFormatters.DATE_TIMESTAMP_FORMATTER);
+      } catch (DateTimeParseException ignored) {
+        ZonedDateTime zdt = ZonedDateTime.parse(date, DateTimeFormatter.ISO_DATE_TIME);
+        ldt = zdt.withZoneSameInstant(ZoneOffset.UTC).toLocalDateTime();
+      }
+      this.date = ldt.toLocalDate();
     } catch (DateTimeParseException e) {
       throw new ExpressionEvaluationException(
           String.format("date:%s in unsupported format, please use 'yyyy-MM-dd'", date));

core/src/main/java/org/opensearch/sql/data/model/ExprTimeValue.java

@@ -10,8 +10,10 @@
 import java.time.Instant;
 import java.time.LocalDate;
 import java.time.LocalTime;
+import java.time.OffsetTime;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
 import java.time.format.DateTimeParseException;
 import java.util.Objects;
 import lombok.RequiredArgsConstructor;
@@ -34,7 +36,23 @@ public class ExprTimeValue extends AbstractExprValue {
    */
   public ExprTimeValue(String time) {
     try {
-      this.time = LocalTime.parse(time, DateTimeFormatters.TIME_TIMESTAMP_FORMATTER);
+      LocalTime lt;
+      try {
+        lt = LocalTime.parse(time, DateTimeFormatters.TIME_TIMESTAMP_FORMATTER);
+      } catch (DateTimeParseException ignore) {
+        try {
+          lt =
+              ZonedDateTime.parse(time, DateTimeFormatter.ISO_DATE_TIME)
+                  .withZoneSameInstant(ZoneOffset.UTC)
+                  .toLocalTime();
+        } catch (DateTimeParseException ignore2) {
+          lt =
+              OffsetTime.parse(time, DateTimeFormatter.ISO_TIME)
+                  .withOffsetSameInstant(ZoneOffset.UTC)
+                  .toLocalTime();
+        }
+      }
+      this.time = lt;
     } catch (DateTimeParseException e) {
       throw new ExpressionEvaluationException(
           String.format("time:%s in unsupported format, please use 'HH:mm:ss[.SSSSSSSSS]'", time));

core/src/main/java/org/opensearch/sql/executor/QueryService.java

@@ -265,7 +265,11 @@ public RelNode optimize(RelNode plan, CalcitePlanContext context) {
 
   private boolean isCalciteFallbackAllowed() {
     if (settings != null) {
-      return settings.getSettingValue(Settings.Key.CALCITE_FALLBACK_ALLOWED);
+      Boolean fallback_allowed = settings.getSettingValue(Settings.Key.CALCITE_FALLBACK_ALLOWED);
+      if (fallback_allowed == null) {
+        return false;
+      }
+      return fallback_allowed;
     } else {
       return true;
     }

integ-test/src/test/java/org/opensearch/sql/calcite/standalone/CalcitePPLDateTimeBuiltinFunctionIT.java

@@ -707,6 +707,27 @@ public void testComparisonBetweenDateAndTimestamp() throws IOException {
     verifyDataRows(actual, rows(2));
   }
 
+  @Test
+  public void testComparisonWithIso8601DateLiteral() {
+    Object[][] tests = {
+      {"date_optional_time = '1984-04-12T09:07:42.000Z'", 2},
+      {"date_time = '1984-04-12T07:07:42-02:00'", 2},
+      {"date = '1984-04-12'", 2},
+      {"date = '1984-04-12T09:07:42.000Z'", 2},
+      {"basic_t_time = '1984-04-12T09:07:42.000Z'", 2},
+      {"basic_t_time = '10:07:42.000+01:00'", 2}
+    };
+    for (Object[] pair : tests) {
+      String query = (String) pair[0];
+      int result = (int) pair[1];
+      JSONObject actual =
+          executeQuery(
+              String.format(
+                  "source=%s | where %s | stats COUNT() AS cnt", TEST_INDEX_DATE_FORMATS, query));
+      verifyDataRows(actual, rows(result));
+    }
+  }
+
   @Test
   public void testAddSubTime() throws IOException {
     JSONObject actual =