Preserve TIMESTAMP_NTZ type name in ResultSetMetaData (#1495)

NEXT_CHANGELOG.md

@@ -19,6 +19,7 @@
 - Fixed `getColumns()` flooding the `DriverManager` log writer with caught-and-recovered `Invalid column index` stack traces.
 - Fixed timezone-shifted TIMESTAMP values when retrieving nested complex types (STRUCT/ARRAY/MAP) with `EnableComplexDatatypeSupport=1`.
 - Fixed `DatabricksDatabaseMetaData.supportsBatchUpdates()` always returning `false`, which caused batch-aware JDBC clients (e.g. Apache Hop) to skip `executeBatch()` and fall back to one INSERT per row. It now returns `true` when `EnableBatchedInserts=1`, so those clients use the optimized multi-row INSERT path.
+- Fixed `ResultSetMetaData.getColumnTypeName()` returning `TIMESTAMP` for `TIMESTAMP_NTZ` columns (e.g. `SELECT MIN(ntz_col) ...`), a regression from 3.0.7. By default the driver now preserves the `TIMESTAMP_NTZ` type name across the SEA, Thrift, and describe-query metadata paths; `getColumnType()` continues to report `java.sql.Types.TIMESTAMP`. Set the new connection property `EnableTimestampNtzTypeName=0` to restore the previous behavior (report `TIMESTAMP`), which matches the legacy (v2.x.x) driver. ([#1495](https://github.com/databricks/databricks-jdbc/issues/1495))
 
 ---
 *Note: When making changes, please add your change under the appropriate section

src/main/java/com/databricks/jdbc/api/impl/DatabricksConnectionContext.java

@@ -1100,6 +1100,11 @@ public boolean isGeoSpatialSupportEnabled() {
     return getParameter(DatabricksJdbcUrlParams.ENABLE_GEOSPATIAL_SUPPORT).equals("1");
   }
 
+  @Override
+  public boolean isTimestampNtzTypeNameEnabled() {
+    return getParameter(DatabricksJdbcUrlParams.ENABLE_TIMESTAMP_NTZ_TYPE_NAME).equals("1");
+  }
+
   @Override
   public boolean isRequestTracingEnabled() {
     return getParameter(DatabricksJdbcUrlParams.ENABLE_REQUEST_TRACING).equals("1");

src/main/java/com/databricks/jdbc/api/impl/DatabricksResultSetMetaData.java

@@ -90,12 +90,18 @@ public DatabricksResultSetMetaData(
       if (resultManifest.getSchema().getColumnCount() > 0) {
         for (ColumnInfo columnInfo : resultManifest.getSchema().getColumns()) {
           ColumnInfoTypeName columnTypeName = columnInfo.getTypeName();
-          // For TIMESTAMP_NTZ columns, getTypeName() returns null.
-          // use typeText (initially "TIMESTAMP_NTZ") to identify the type,
-          // overwrite it to "TIMESTAMP" to maintain parity with thrift output.
+          // For TIMESTAMP_NTZ columns, getTypeName() returns null because the SDK
+          // ColumnInfoTypeName enum has no TIMESTAMP_NTZ value. Use typeText to
+          // identify the type and map it to the TIMESTAMP enum so the java.sql type
+          // resolves to Types.TIMESTAMP. By default the "TIMESTAMP_NTZ" typeText is
+          // preserved so getColumnTypeName() reports the actual server type
+          // (see GitHub issue #1495); when EnableTimestampNtzTypeName=0 it is
+          // normalized to "TIMESTAMP" to match the legacy (v2.x.x) driver.
           if (columnInfo.getTypeText().equalsIgnoreCase(TIMESTAMP_NTZ)) {
             columnTypeName = ColumnInfoTypeName.TIMESTAMP;
-            columnInfo.setTypeText(TIMESTAMP);
+            if (!ctx.isTimestampNtzTypeNameEnabled()) {
+              columnInfo.setTypeText(TIMESTAMP);
+            }
           }
 
           // Check if we need to convert geospatial types to string when geospatial support is
@@ -215,8 +221,12 @@ public DatabricksResultSetMetaData(
                   ? arrowMetadata.get(columnIndex)
                   : getTypeTextFromTypeDesc(columnDesc.getTypeDesc());
 
-          // Normalize TIMESTAMP_NTZ to TIMESTAMP for consistency with SEA path
-          if (columnTypeText != null && columnTypeText.equalsIgnoreCase(TIMESTAMP_NTZ)) {
+          // Normalize TIMESTAMP_NTZ to TIMESTAMP only when the type-name feature is
+          // disabled (legacy/v2.x.x parity); by default the NTZ type name is preserved
+          // (see GitHub issue #1495).
+          if (columnTypeText != null
+              && columnTypeText.equalsIgnoreCase(TIMESTAMP_NTZ)
+              && !ctx.isTimestampNtzTypeNameEnabled()) {
             columnTypeText = TIMESTAMP;
           }
 
@@ -461,8 +471,9 @@ public DatabricksResultSetMetaData(
       String baseTypeName = metadataResultSetBuilder.stripBaseTypeName(columnTypeText);
       ColumnInfoTypeName columnTypeName = DatabricksTypeUtil.getColumnInfoType(baseTypeName);
 
-      // Normalize columnTypeText for types that have a canonical display name
-      if (baseTypeName.equals(TIMESTAMP_NTZ)) {
+      // By default the TIMESTAMP_NTZ type name is preserved (see GitHub issue #1495);
+      // normalize it to TIMESTAMP only when EnableTimestampNtzTypeName=0 (legacy/v2.x.x parity).
+      if (baseTypeName.equals(TIMESTAMP_NTZ) && !ctx.isTimestampNtzTypeNameEnabled()) {
         columnTypeText = TIMESTAMP;
       }
 

src/main/java/com/databricks/jdbc/api/internal/IDatabricksConnectionContext.java

@@ -311,6 +311,13 @@ public interface IDatabricksConnectionContext {
   /** Returns true if driver returns GEOMETRY and GEOGRAPHY types natively. */
   boolean isGeoSpatialSupportEnabled();
 
+  /**
+   * Returns true if {@code ResultSetMetaData.getColumnTypeName()} should report "TIMESTAMP_NTZ" for
+   * TIMESTAMP_NTZ columns. When false, the type name is normalized to "TIMESTAMP" to match the
+   * legacy (v2.x.x) driver behavior.
+   */
+  boolean isTimestampNtzTypeNameEnabled();
+
   /** Returns the size for HTTP connection pool */
   int getHttpConnectionPoolSize() throws DatabricksValidationException;
 

src/main/java/com/databricks/jdbc/common/DatabricksJdbcUrlParams.java

@@ -136,6 +136,12 @@ public enum DatabricksJdbcUrlParams {
       "EnableGeoSpatialSupport",
       "flag to enable native support of GEOMETRY and GEOGRAPHY data types",
       "1"),
+  ENABLE_TIMESTAMP_NTZ_TYPE_NAME(
+      "EnableTimestampNtzTypeName",
+      "When enabled (default), ResultSetMetaData.getColumnTypeName() reports "
+          + "\"TIMESTAMP_NTZ\" for TIMESTAMP_NTZ columns. Set to 0 to report "
+          + "\"TIMESTAMP\" instead, matching the legacy (v2.x.x) driver behavior.",
+      "1"),
   ROWS_FETCHED_PER_BLOCK(
       "RowsFetchedPerBlock",
       "The maximum number of rows that a query returns at a time.",

src/test/java/com/databricks/jdbc/api/impl/DatabricksResultSetMetaDataTest.java

@@ -2,6 +2,7 @@
 
 import static com.databricks.jdbc.common.Nullable.NULLABLE;
 import static com.databricks.jdbc.common.util.DatabricksTypeUtil.TIMESTAMP;
+import static com.databricks.jdbc.common.util.DatabricksTypeUtil.TIMESTAMP_NTZ;
 import static com.databricks.jdbc.common.util.DatabricksTypeUtil.VARIANT;
 import static org.junit.jupiter.api.Assertions.*;
 import static org.mockito.Mockito.when;
@@ -43,6 +44,8 @@ public class DatabricksResultSetMetaDataTest {
   void setUp() {
     connectionContext = Mockito.mock(IDatabricksConnectionContext.class);
     when(connectionContext.getDefaultStringColumnLength()).thenReturn(255);
+    // Production default: report TIMESTAMP_NTZ type names (EnableTimestampNtzTypeName=1).
+    when(connectionContext.isTimestampNtzTypeNameEnabled()).thenReturn(true);
     DatabricksThreadContextHolder.setConnectionContext(connectionContext);
   }
 
@@ -135,11 +138,36 @@ public void testColumnsWithTimestampNTZ() throws SQLException {
         new DatabricksResultSetMetaData(STATEMENT_ID, resultManifest, false, connectionContext);
     assertEquals(1, metaData.getColumnCount());
     assertEquals("timestamp_ntz", metaData.getColumnName(1));
-    assertEquals(TIMESTAMP, metaData.getColumnTypeName(1));
+    // The TIMESTAMP_NTZ type text must be preserved (see GitHub issue #1495);
+    // it previously was normalized to TIMESTAMP. The java.sql type is still
+    // Types.TIMESTAMP because TIMESTAMP_NTZ is a timestamp without timezone.
+    assertEquals(TIMESTAMP_NTZ, metaData.getColumnTypeName(1));
     assertEquals(Types.TIMESTAMP, metaData.getColumnType(1));
     assertEquals(10, metaData.getTotalRows());
   }
 
+  @Test
+  public void testColumnsWithTimestampNTZ_legacyTypeNameDisabled() throws SQLException {
+    // With EnableTimestampNtzTypeName=0 the type name is normalized to TIMESTAMP to
+    // match the legacy (v2.x.x) driver behavior. The java.sql type is unchanged.
+    IDatabricksConnectionContext legacyContext = Mockito.mock(IDatabricksConnectionContext.class);
+    when(legacyContext.getDefaultStringColumnLength()).thenReturn(255);
+    when(legacyContext.isTimestampNtzTypeNameEnabled()).thenReturn(false);
+
+    ResultManifest resultManifest = new ResultManifest();
+    resultManifest.setTotalRowCount(10L);
+    ResultSchema schema = new ResultSchema();
+    schema.setColumnCount(1L);
+    schema.setColumns(List.of(getColumn("timestamp_ntz", null, "TIMESTAMP_NTZ")));
+    resultManifest.setSchema(schema);
+
+    DatabricksResultSetMetaData metaData =
+        new DatabricksResultSetMetaData(STATEMENT_ID, resultManifest, false, legacyContext);
+    assertEquals("timestamp_ntz", metaData.getColumnName(1));
+    assertEquals(TIMESTAMP, metaData.getColumnTypeName(1));
+    assertEquals(Types.TIMESTAMP, metaData.getColumnType(1));
+  }
+
   @Test
   public void testDatabricksResultSetMetaDataInitialization() throws SQLException {
     // Instantiate the DatabricksResultSetMetaData
@@ -193,7 +221,7 @@ public void testDatabricksResultSetMetaDataInitialization_DescribeQuery() throws
       {"col_decimal", "decimal(10,2)", "DECIMAL", Types.DECIMAL, 10, 2},
       {"col_date", "date", "DATE", Types.DATE, 10, 0},
       {"col_timestamp", "timestamp", "TIMESTAMP", Types.TIMESTAMP, 29, 9},
-      {"col_timestamp_ntz", "timestamp_ntz", "TIMESTAMP", Types.TIMESTAMP, 29, 9},
+      {"col_timestamp_ntz", "timestamp_ntz", "TIMESTAMP_NTZ", Types.TIMESTAMP, 29, 9},
       {"col_bool", "boolean", "BOOLEAN", Types.BOOLEAN, 1, 0},
       {"col_binary", "binary", "BINARY", Types.BINARY, 1, 0},
       {"col_struct", "struct<col_int:int,col_string:string>", "STRUCT", Types.STRUCT, 255, 0},