Added Warning logs when detecting precision less Oracle numbers.

Author: MrRahulSharma

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

@@ -24,6 +24,8 @@
 import io.cdap.plugin.db.ColumnType;
 import io.cdap.plugin.db.DBRecord;
 import io.cdap.plugin.db.SchemaReader;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -48,6 +50,8 @@
  */
 public class OracleSourceDBRecord extends DBRecord {
 
+  private static final Logger LOG = LoggerFactory.getLogger(OracleSourceDBRecord.class);
+
   public OracleSourceDBRecord(StructuredRecord record, List<ColumnType> columnTypes) {
     this.record = record;
     this.columnTypes = columnTypes;
@@ -214,16 +218,31 @@ private void handleOracleSpecificType(ResultSet resultSet, StructuredRecord.Buil
         if (Double.class.getTypeName().equals(resultSet.getMetaData().getColumnClassName(columnIndex))) {
           recordBuilder.set(field.getName(), resultSet.getDouble(columnIndex));
         } else {
+          int scaleInSchema = getScale(field.getSchema());
+          if (precision == 0 && scaleInSchema == 0) {
+            BigDecimal value = BigDecimal.valueOf(resultSet.getDouble(columnIndex));
+            if (value != null && !containsIntegerValue(value)) {
+              LOG.warn(String.format("Precision loss detected in the field '%s'. "
+                  + "Scale in the data='%s' scale present in the schema='%s'.",
+                  field.getName(),
+                  value.scale(),
+                  scaleInSchema));
+            }
+          }
           // It's required to pass 'scale' parameter since in the case of Oracle, scale of 'BigDecimal' depends on the
           // scale set in the logical schema. For example for value '77.12' if the scale set in the logical schema is
           // set to 4 then the number will change to '77.1200'. Also if the value is '22.1274' and the logical schema
           // scale is set to 2 then the decimal value used will be '22.13' after rounding.
-          BigDecimal decimal = resultSet.getBigDecimal(columnIndex, getScale(field.getSchema()));
+          BigDecimal decimal = resultSet.getBigDecimal(columnIndex, scaleInSchema);
           recordBuilder.setDecimal(field.getName(), decimal);
         }
     }
   }
 
+  private boolean containsIntegerValue(BigDecimal value) {
+    return value.remainder(BigDecimal.ONE).compareTo(BigDecimal.ZERO) == 0;
+  }
+
   /**
    * Get the scale set in Non-nullable schema associated with the schema
    * */

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

@@ -19,6 +19,8 @@
 import com.google.common.collect.ImmutableSet;
 import io.cdap.cdap.api.data.schema.Schema;
 import io.cdap.plugin.db.CommonSchemaReader;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
@@ -42,6 +44,11 @@ public class OracleSourceSchemaReader extends CommonSchemaReader {
   public static final int LONG = -1;
   public static final int LONG_RAW = -4;
 
+  /**
+   * Logger instance for Oracle Schema reader.
+   */
+  private static final Logger LOG = LoggerFactory.getLogger(OracleSourceSchemaReader.class);
+
   public static final Set<Integer> ORACLE_TYPES = ImmutableSet.of(
     INTERVAL_DS,
     INTERVAL_YM,
@@ -100,6 +107,11 @@ public Schema getSchema(ResultSetMetaData metadata, int index) throws SQLExcepti
             // reference : https://docs.oracle.com/cd/B28359_01/server.111/b28318/datatype.htm#CNCPT1832
             precision = 38;
             scale = 0;
+            LOG.warn(String.format("%s type with undefined precision and scale is detected, "
+                    + "there may be a precision loss while running the pipeline. "
+                    + "Please define an output precision and scale for field '%s' to avoid precision loss.",
+                metadata.getColumnTypeName(index),
+                metadata.getColumnName(index)));
           }
           return Schema.decimalOf(precision, scale);
         }