Enforce unique constraints on parquet column

While dealing with large datasets when its not feasible to load in memory, how can one enforce unique constraint on a parquet column?

Is there any provision right now to enforce unique constraint on a parquet column? 

**Reporter**: [Rohan](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=rpadshah)

_{**Note**: *This issue was originally created as [PARQUET-2455](https://issues.apache.org/jira/browse/PARQUET-2455). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

The issue names no files, tests, or entry points. Start by clarifying the intended Parquet-Java behavior and checking whether existing constraint support is relevant; done requires a concrete, implementable way to enforce uniqueness on a Parquet column for datasets that do not fit in memory.

Written by the indexing model from the issue text.