Add a way to append encoded blocks in ParquetFileWriter

[asfimport]

Concatenating two files together currently requires reading the source files and rewriting the content from scratch. This ends up taking a lot of memory, even if the data is already encoded correctly and blocks just need to be appended and have their metadata updated. Merging two files should be fast and not take much memory.

Reporter: Ryan Blue / @rdblue
Assignee: Ryan Blue / @rdblue

Related issues:

• CLONE - Add a way to append encoded blocks in ParquetFileWriter (is cloned by)
• [Parquet] Support Alter Table/Partition Concatenate (relates to)

PRs and other links:

• PR #278

_{Note: This issue was originally created as PARQUET-382. Please see the migration documentation for further details.}

[asfimport]

Ryan Blue / @rdblue:
Merged #278. Thanks for reviewing, Sergio!