int allocateOutputColumn(TypeInfo typeInfo,
        DataTypePhysicalVariation dataTypePhysicalVariation) throws HiveException {

        if (initialOutputCol < 0) {
          // This is a test calling.
          return 0;
        }

        // CONCERN: We currently differentiate DECIMAL columns by their precision and scale...,
        // which could lead to a lot of extra unnecessary scratch columns.
        String vectorTypeName = getScratchName(typeInfo);
        int relativeCol = allocateOutputColumnInternal(vectorTypeName, dataTypePhysicalVariation);
        return initialOutputCol + relativeCol;
      }
Context class for vectorization execution.
Main role is to map column names to column indices and serves as a
factory class for building vectorized expressions out of descriptors.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorizationContext.java