@Override
  public FSDataOutputStream append(Path arg0, int arg1, Progressable arg2) throws IOException {
    LlapCacheAwareFs.CacheAwareInputStream ctx = getCtx(arg0);
    return ctx.getFs().append(ctx.path, arg1, arg2);
  }
This is currently only used by Parquet; however, a generally applicable approach is used -
you pass in a set of offset pairs for a file, and the file is cached with these boundaries.
Don't add anything format specific here.
ql/src/java/org/apache/hadoop/hive/llap/LlapCacheAwareFs.java