Truncate stats from Parquet files

[vgankidi]

Lower and upper bound values from Parquet files are not currently truncated, which takes more space than necessary in manifests. Truncating strings and binary values will probably improve performance for large tables.

This PR adds a configurable table property "write.metadata.truncate-length" with a default value of 16. Default behavior is to truncate binary values to <= 16 bytes and strings to <= 16 unicode characters.

Resolves #113

[rdblue]

@vgankidi, it looks like this is based on an old version of your branch. Could you update it to the current?

[rdblue]

@edgarRd, FYI. This PR has methods to truncate binary and string values to avoid writing huge stats in table metadata. Probably something you'll want to use for ORC.

[rdblue]

I don't think there is a need for this to be left. The truncate length should always be included when getting metrics.

The version that uses the default is called from two places:

• ParquetWriteAdapter that is created by Parquet.write when the internal ParquetWriter is not used
• SparkTableUtil that reads Parquet footers when converting Hive tables to Iceberg metadata

I think both should be updated. The write adapter should use the config setting, and the Spark util method can default this inline. Then we can get rid of this method.

[vgankidi]

Yes, would be good to get rid of this. I updated the PR with these changes.

[rdblue]

Thanks for the quick fixes, @vgankidi! Merged.