Use timestamp in gregorian calendar format.

database-commons/src/main/java/io/cdap/plugin/util/DBUtils.java

@@ -37,9 +37,13 @@
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Types;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
 import java.util.Hashtable;
 import java.util.List;
 import java.util.Objects;
+import java.util.TimeZone;
 import javax.annotation.Nullable;
 import javax.management.InstanceNotFoundException;
 import javax.management.IntrospectionException;
@@ -55,6 +59,18 @@
 public final class DBUtils {
   private static final Logger LOG = LoggerFactory.getLogger(DBUtils.class);
 
+  private static final Calendar PURE_GREGORIAN_CALENDAR = createPureGregorianCalender();
+
+  // Java by default uses October 15, 1582 as a Gregorian cut over date.
+  // Any timestamp created with time less than this cut over date is treated as Julian date.
+  // This causes old dates from database such as 0001-01-01 01:00:00 mapped to 0000-12-30
+  // Get the pure gregorian calendar so that all dates are treated as gregorian format.
+  private static Calendar createPureGregorianCalender() {
+    GregorianCalendar gc = new GregorianCalendar();
+    gc.setGregorianChange(new Date(Long.MIN_VALUE));
+    return gc;
+  }
+
   /**
    * Performs any Database related cleanup
    *
@@ -116,7 +132,7 @@ public static Object transformValue(int sqlType, int precision, int scale,
         case Types.TIME:
           return resultSet.getTime(columnIndex);
         case Types.TIMESTAMP:
-          return resultSet.getTimestamp(columnIndex);
+          return resultSet.getTimestamp(columnIndex, PURE_GREGORIAN_CALENDAR);
         case Types.ROWID:
           return resultSet.getString(columnIndex);
         case Types.BLOB:

oracle-plugin/src/main/java/io/cdap/plugin/oracle/OracleConnectorConfig.java

@@ -58,7 +58,7 @@ public String getConnectionString() {
     } else if (OracleConstants.SERVICE_CONNECTION_TYPE.equals(getConnectionType())) {
       return String.format(OracleConstants.ORACLE_CONNECTION_STRING_SERVICE_NAME_FORMAT, host, getPort(), database);
     } else {
-      return String.format(OracleConstants.ORACLE_CONNECTION_STRING_SID_FORMAT, host, getPort(),database);
+      return String.format(OracleConstants.ORACLE_CONNECTION_STRING_SID_FORMAT, host, getPort(), database);
     }
   }
 

oracle-plugin/src/main/java/io/cdap/plugin/oracle/OracleConstants.java

@@ -34,5 +34,5 @@ private OracleConstants() {
   public static final String CONNECTION_TYPE = "connectionType";
   public static final String ROLE = "role";
   public static final String NAME_DATABASE = "database";
-  public static final String TNS_CONNECTION_TYPE= "TNS";
+  public static final String TNS_CONNECTION_TYPE = "TNS";
 }