public void setInsertOverwrite(boolean isInsertOverwrite) {
    this.isInsertOverwrite = isInsertOverwrite;
  }
Whether this is CREATE TABLE SELECT or CREATE MATERIALIZED VIEW statement
Set by semantic analyzer this is required because CTAS/CM requires some special logic
in mvFileToFinalPath
ql/src/java/org/apache/hadoop/hive/ql/plan/FileSinkDesc.java