diff --git a/utils/dataconvert/dataconvert.cpp b/utils/dataconvert/dataconvert.cpp
index b53f42e74..7b25a33a7 100644
--- a/utils/dataconvert/dataconvert.cpp
+++ b/utils/dataconvert/dataconvert.cpp
@@ -2975,7 +2975,7 @@ void DataConvert::joinColTypeForUnion(datatypes::SystemCatalog::TypeHolderStd& u
         case datatypes::SystemCatalog::UBIGINT:
         case datatypes::SystemCatalog::UDECIMAL:
 
-          if (type.scale != 0)
+          if (type.scale != 0 && unionedType.scale != 0)
           {
             const unsigned int digitsBeforeDecimal = type.precision - type.scale;
             const unsigned int digitsBeforeDecimalUnion = unionedType.precision - unionedType.scale;
@@ -2988,7 +2988,18 @@ void DataConvert::joinColTypeForUnion(datatypes::SystemCatalog::TypeHolderStd& u
             }
           }
 
-          unionedType.precision = std::max(type.precision, unionedType.precision);
+          // Handle the scenario where the upstream code assigns special values of 9999
+          // and -1 as the precision of the unionedType.
+          if ((unionedType.precision == 9999 || unionedType.precision == -1) &&
+              (type.precision != 9999 && type.precision != -1))
+          {
+            unionedType.precision = type.precision;
+          }
+          else
+          {
+            unionedType.precision = std::max(type.precision, unionedType.precision);
+          }
+
           unionedType.scale = std::max(type.scale, unionedType.scale);
 
           if (datatypes::Decimal::isWideDecimalTypeByPrecision(unionedType.precision))
@@ -3056,6 +3067,10 @@ void DataConvert::joinColTypeForUnion(datatypes::SystemCatalog::TypeHolderStd& u
         case datatypes::SystemCatalog::UFLOAT:
         case datatypes::SystemCatalog::UDOUBLE:
         case datatypes::SystemCatalog::LONGDOUBLE:
+          if (datatypes::isWideDecimalType(type.colDataType, type.colWidth))
+            unionedType = type;
+          break;
+
         default: break;
       }