Parquet OutputFormat should allow controlling the file size

To generate the most efficient on disk file, the size of the file is important to control. It would be nice if we could configure the ouputformat to roll over new files when it reaches the right size and start a new file.

There's currently no easy way to tune this and requires indirect tuning (number of reduces, map input size).

**Reporter**: [Nong Li](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=nongli) / @nongli

_{**Note**: *This issue was originally created as [PARQUET-17](https://issues.apache.org/jira/browse/PARQUET-17). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

该 issue 提到了 Parquet OutputFormat，但没有指定任何文件或测试。首先定位这个入口点，并确定当前如何处理输出文件大小；完成的标准是提供一个可配置的大小阈值，在达到该阈值时将输出滚动到新文件中。

由索引模型根据 Issue 内容生成。