private int getSparseOrcIndexFromDenseDest(int denseColIx) {
      // denseColIx is index in ORC writer with includes. We -1 to skip the root column; get the
      // original text file index; then add the root column again. This makes many assumptions.
      // Also this only works for primitive types; vectordeserializer only supports these anyway.
      // The mapping for complex types with sub-cols in ORC would be much more difficult to build.
      return columnIds.get(denseColIx - 1) + 1;
    }
For !doesSourceHaveIncludes case, stores global column IDs to verify writer columns.
For doesSourceHaveIncludes case, stores source column IDs used to map things.
llap-server/src/java/org/apache/hadoop/hive/llap/io/encoded/SerDeEncodedDataReader.java