fix(core): cluster A — span() output column type for date/time UDT

Recognize the new sandbox DateOnlyType / TimeOnlyType UDT markers in:
- OpenSearchTypeFactory.convertAnalyticsEngineRelDataTypeToExprType:
  DateOnlyType → ExprCoreType.DATE, TimeOnlyType → ExprCoreType.TIME so the
  user-visible response schema labels span() bucket columns as `date` /
  `time` instead of `timestamp`.
- AnalyticsExecutionEngine.toExprValue: when the column carries a
  DateOnlyType marker, strip the trailing ` HH:MM:SS` from the
  Timestamp(ms)-formatted wire value so dates render as `YYYY-MM-DD`.
  Symmetric handling for TimeOnlyType strips the `1970-01-01 ` prefix.

Pairs with the sandbox schema-builder change in
opensearch-project/OpenSearch@b69c5ff8888.

Author: vinaykpud

core/src/main/java/org/opensearch/sql/calcite/utils/OpenSearchTypeFactory.java

@@ -47,7 +47,9 @@
 import org.apache.calcite.sql.type.SqlTypeUtil;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.opensearch.analytics.schema.BinaryType;
+import org.opensearch.analytics.schema.DateOnlyType;
 import org.opensearch.analytics.schema.IpType;
+import org.opensearch.analytics.schema.TimeOnlyType;
 import org.opensearch.sql.calcite.type.AbstractExprRelDataType;
 import org.opensearch.sql.calcite.type.ExprBinaryType;
 import org.opensearch.sql.calcite.type.ExprDateType;
@@ -293,6 +295,14 @@ public static ExprType convertAnalyticsEngineRelDataTypeToExprType(RelDataType t
     if (type instanceof BinaryType) {
       return BINARY;
     }
+    // Sandbox UDT markers for format-classified date columns (Timestamp(ms)-backed wire,
+    // user-visible label downgraded to date / time).
+    if (type instanceof DateOnlyType) {
+      return DATE;
+    }
+    if (type instanceof TimeOnlyType) {
+      return TIME;
+    }
     return convertRelDataTypeToExprType(type);
   }
 

core/src/main/java/org/opensearch/sql/executor/analytics/AnalyticsExecutionEngine.java

@@ -20,7 +20,9 @@
 import org.opensearch.analytics.exec.QueryPlanExecutor;
 import org.opensearch.analytics.exec.profile.ProfiledResult;
 import org.opensearch.analytics.schema.BinaryType;
+import org.opensearch.analytics.schema.DateOnlyType;
 import org.opensearch.analytics.schema.IpType;
+import org.opensearch.analytics.schema.TimeOnlyType;
 import org.opensearch.common.network.InetAddresses;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.sql.ast.statement.ExplainMode;
@@ -54,6 +56,11 @@ public class AnalyticsExecutionEngine implements ExecutionEngine {
   private static final Pattern EPOCH_DATE_TIME_PREFIX =
       Pattern.compile("^1970-01-01[ T](\\d{2}:\\d{2}:\\d{2}(?:\\.\\d+)?)$");
 
+  // DATE-typed columns whose wire is Timestamp(ms) arrive as "YYYY-MM-DD HH:mm:ss";
+  // when the column carries a DateOnlyType marker we strip the time suffix.
+  private static final Pattern DATE_WITH_MIDNIGHT_TIME =
+      Pattern.compile("^(\\d{4}-\\d{2}-\\d{2})[ T]\\d{2}:\\d{2}:\\d{2}(?:\\.\\d+)?$");
+
   private final QueryPlanExecutor<RelNode, Iterable<Object[]>> planExecutor;
 
   public AnalyticsExecutionEngine(QueryPlanExecutor<RelNode, Iterable<Object[]>> planExecutor) {
@@ -241,6 +248,20 @@ private static ExprValue toExprValue(Object value, RelDataType type) {
         return ExprValueUtils.stringValue(Base64.getEncoder().encodeToString(bytes));
       }
     }
+    // span(date-typed) returns Timestamp(ms) wire with midnight time; render as YYYY-MM-DD only.
+    if (type instanceof DateOnlyType && value instanceof String s) {
+      var m = DATE_WITH_MIDNIGHT_TIME.matcher(s);
+      if (m.matches()) {
+        return ExprValueUtils.stringValue(m.group(1));
+      }
+    }
+    // span(time-typed) returns Timestamp(ms) wire with 1970-01-01 prefix; render as HH:mm:ss only.
+    if (type instanceof TimeOnlyType && value instanceof String s) {
+      var m = EPOCH_DATE_TIME_PREFIX.matcher(s);
+      if (m.matches()) {
+        return ExprValueUtils.stringValue(m.group(1));
+      }
+    }
     // List elements that look like a sentinel-epoch-prefixed time render as HH:mm:ss only.
     if (value instanceof List<?> list) {
       return ExprValueUtils.collectionValue(stripEpochDatePrefixInList(list));

core/src/test/java/org/opensearch/sql/executor/analytics/AnalyticsExecutionEngineTest.java

@@ -30,7 +30,9 @@
 import org.junit.jupiter.api.Test;
 import org.opensearch.analytics.exec.QueryPlanExecutor;
 import org.opensearch.analytics.schema.BinaryType;
+import org.opensearch.analytics.schema.DateOnlyType;
 import org.opensearch.analytics.schema.IpType;
+import org.opensearch.analytics.schema.TimeOnlyType;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.sql.calcite.CalcitePlanContext;
 import org.opensearch.sql.calcite.SysLimit;
@@ -237,6 +239,40 @@ void executeRelNode_binaryColumnRendersAsBase64() {
         "byte[] should base64-encode to match OpenSearch binary wire format. " + dump);
   }
 
+  /**
+   * DateOnlyType column value "YYYY-MM-DD HH:MM:SS" → schema "date" + value stripped to YYYY-MM-DD.
+   */
+  @Test
+  void executeRelNode_dateOnlyTypeStripsTimeSuffix() {
+    RelNode relNode = mockRelNodeWithType("d", new DateOnlyType(RelDataTypeSystem.DEFAULT, true));
+    Iterable<Object[]> rows = Collections.singletonList(new Object[] {"1984-04-12 00:00:00"});
+    stubExecutorWith(relNode, rows);
+
+    QueryResponse response = executeAndCapture(relNode);
+    String dump = dumpResponse(response);
+
+    assertEquals(ExprCoreType.DATE, response.getSchema().getColumns().get(0).getExprType(), dump);
+    assertEquals(
+        "1984-04-12", response.getResults().get(0).tupleValue().get("d").stringValue(), dump);
+  }
+
+  /**
+   * TimeOnlyType column value "1970-01-01 HH:MM:SS" → schema "time" + value stripped to HH:MM:SS.
+   */
+  @Test
+  void executeRelNode_timeOnlyTypeStripsEpochDatePrefix() {
+    RelNode relNode = mockRelNodeWithType("t", new TimeOnlyType(RelDataTypeSystem.DEFAULT, true));
+    Iterable<Object[]> rows = Collections.singletonList(new Object[] {"1970-01-01 09:00:00"});
+    stubExecutorWith(relNode, rows);
+
+    QueryResponse response = executeAndCapture(relNode);
+    String dump = dumpResponse(response);
+
+    assertEquals(ExprCoreType.TIME, response.getSchema().getColumns().get(0).getExprType(), dump);
+    assertEquals(
+        "09:00:00", response.getResults().get(0).tupleValue().get("t").stringValue(), dump);
+  }
+
   /** TIME-typed list elements arrive as "1970-01-01[ T]HH:mm:ss[.frac]" — strip the prefix. */
   @Test
   void executeRelNode_listOfStringStripsEpochDatePrefix() {