Allowing for timestamps without a time zone.

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcToArrow.java

@@ -131,7 +131,7 @@ public static VectorSchemaRoot sqlToArrow(
  public static VectorSchemaRoot sqlToArrow(ResultSet resultSet) throws SQLException, IOException {
  Preconditions.checkNotNull(resultSet, "JDBC ResultSet object can not be null");
 
- return sqlToArrow(resultSet, Calendar.getInstance(TimeZone.getTimeZone("UTC"), Locale.ROOT));
+ return sqlToArrow(resultSet, (Calendar) null);
  }
 
  /**
@@ -147,20 +147,19 @@ public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, BaseAllocator all
  Preconditions.checkNotNull(resultSet, "JDBC ResultSet object can not be null");
  Preconditions.checkNotNull(allocator, "Memory Allocator object can not be null");
 
- return sqlToArrow(resultSet, allocator, Calendar.getInstance(TimeZone.getTimeZone("UTC"), Locale.ROOT));
+ return sqlToArrow(resultSet, allocator, null);
  }
 
  /**
  * For the given JDBC {@link ResultSet}, fetch the data from Relational DB and convert it to Arrow objects.
  *
  * @param resultSet ResultSet to use to fetch the data from underlying database
- * @param calendar Calendar instance to use for Date, Time and Timestamp datasets.
+ * @param calendar Calendar instance to use for Date, Time and Timestamp datasets, or <code>null</code> if none.
  * @return Arrow Data Objects {@link VectorSchemaRoot}
  * @throws SQLException on error
  */
  public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, Calendar calendar) throws SQLException, IOException {
  Preconditions.checkNotNull(resultSet, "JDBC ResultSet object can not be null");
- Preconditions.checkNotNull(calendar, "Calendar object can not be null");
 
  RootAllocator rootAllocator = new RootAllocator(Integer.MAX_VALUE);
  VectorSchemaRoot root = sqlToArrow(resultSet, rootAllocator, calendar);
@@ -173,15 +172,14 @@ public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, Calendar calendar
  *
  * @param resultSet ResultSet to use to fetch the data from underlying database
  * @param allocator Memory allocator to use.
- * @param calendar Calendar instance to use for Date, Time and Timestamp datasets.
+ * @param calendar Calendar instance to use for Date, Time and Timestamp datasets, or <code>null</code> if none.
  * @return Arrow Data Objects {@link VectorSchemaRoot}
  * @throws SQLException on error
  */
  public static VectorSchemaRoot sqlToArrow(ResultSet resultSet, BaseAllocator allocator, Calendar calendar)
  throws SQLException, IOException {
  Preconditions.checkNotNull(resultSet, "JDBC ResultSet object can not be null");
  Preconditions.checkNotNull(allocator, "Memory Allocator object can not be null");
- Preconditions.checkNotNull(calendar, "Calendar object can not be null");
 
  VectorSchemaRoot root = VectorSchemaRoot.create(
  JdbcToArrowUtils.jdbcToArrowSchema(resultSet.getMetaData(), calendar), allocator);

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcToArrowUtils.java

@@ -120,14 +120,20 @@ public class JdbcToArrowUtils {
  * CLOB --> ArrowType.Utf8
  * BLOB --> ArrowType.Binary
  *
+ * <p>If a {@link java.util.Calendar} is set, {@link java.sql.Timestamp} fields in the {@link java.sql.ResultSet} will
+ * be converted to an Arrow {@link org.apache.arrow.vector.TimeStampVector} using the <code>Calendar</code>'s time
+ * zone. If the <code>Calendar</code> is <code>null</code>, no time zone will be set on the
+ * <code>TimeStampVector</code>.
+ *
  * @param rsmd ResultSetMetaData
  * @return {@link Schema}
  * @throws SQLException on error
  */
  public static Schema jdbcToArrowSchema(ResultSetMetaData rsmd, Calendar calendar) throws SQLException {
 
  Preconditions.checkNotNull(rsmd, "JDBC ResultSetMetaData object can't be null");
- Preconditions.checkNotNull(calendar, "Calendar object can't be null");
+
+ final String tz = (calendar != null) ? calendar.getTimeZone().getID() : null;
 
  List<Field> fields = new ArrayList<>();
  int columnCount = rsmd.getColumnCount();
@@ -178,8 +184,8 @@ public static Schema jdbcToArrowSchema(ResultSetMetaData rsmd, Calendar calendar
  fields.add(new Field(columnName, FieldType.nullable(new ArrowType.Time(TimeUnit.MILLISECOND, 32)), null));
  break;
  case Types.TIMESTAMP:
-  fields.add(new Field(columnName, FieldType.nullable(new ArrowType.Timestamp(TimeUnit.MILLISECOND,
-  calendar.getTimeZone().getID())), null));
+  fields.add(new Field(columnName, FieldType.nullable(new ArrowType.Timestamp(TimeUnit.MILLISECOND, tz)),
+  null));
  break;
  case Types.BINARY:
  case Types.VARBINARY:
@@ -231,7 +237,6 @@ public static void jdbcToArrowVectors(ResultSet rs, VectorSchemaRoot root, Calen
 
  Preconditions.checkNotNull(rs, "JDBC ResultSet object can't be null");
  Preconditions.checkNotNull(root, "JDBC ResultSet object can't be null");
- Preconditions.checkNotNull(calendar, "Calendar object can't be null");
 
  ResultSetMetaData rsmd = rs.getMetaData();
  int columnCount = rsmd.getColumnCount();
@@ -296,9 +301,16 @@ public static void jdbcToArrowVectors(ResultSet rs, VectorSchemaRoot root, Calen
  rs.getTime(i, calendar), !rs.wasNull(), rowCount);
  break;
  case Types.TIMESTAMP:
- // TODO: Need to handle precision such as milli, micro, nano
+ final Timestamp ts;
+ if (calendar != null) {
+ ts = rs.getTimestamp(i, calendar);
+ } else {
+ ts = rs.getTimestamp(i);
+ }
+
+ // TODO: Need to handle precision such as milli, micro, nano
  updateVector((TimeStampVector) root.getVector(columnName),
- rs.getTimestamp(i, calendar), !rs.wasNull(), rowCount);
+ ts, !rs.wasNull(), rowCount);
  break;
  case Types.BINARY:
  case Types.VARBINARY: