Parquet-Java Compatibility

If you have existing code that uses Apache parquet-java's ParquetReader<Group> API and want to switch to Hardwood without rewriting it, the hardwood-parquet-java-compat module provides a drop-in replacement. It implements the same org.apache.parquet.* interfaces backed by Hardwood's reader, so you get Hardwood's performance with minimal code changes.

Features:

• Provides org.apache.parquet.* namespace classes compatible with parquet-java
• Includes Hadoop shims (Path, Configuration) — no Hadoop dependency required
• Supports S3 reading via HadoopInputFile with the same fs.s3a.* configuration properties
• Supports filter predicate pushdown with the standard FilterApi / FilterCompat classes

Reading Local Files

import org.apache.hadoop.fs.Path;
import org.apache.parquet.example.data.Group;
import org.apache.parquet.hadoop.GroupReadSupport;
import org.apache.parquet.hadoop.ParquetReader;

Path path = new Path("data.parquet");

try (ParquetReader<Group> reader = ParquetReader.builder(new GroupReadSupport(), path).build()) {
    Group record;
    while ((record = reader.read()) != null) {
        long id = record.getLong("id", 0);
        String name = record.getString("name", 0);

        Group address = record.getGroup("address", 0);
        String city = address.getString("city", 0);
    }
}

Reading from S3

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.parquet.hadoop.util.HadoopInputFile;

Configuration conf = new Configuration();
conf.set("fs.s3a.access.key", "...");
conf.set("fs.s3a.secret.key", "...");
conf.set("fs.s3a.endpoint", "https://s3.us-east-1.amazonaws.com");

Path path = new Path("s3a://my-bucket/data.parquet");

try (ParquetReader<Group> reader = ParquetReader.builder(new GroupReadSupport(), path)
        .withConf(conf)
        .build()) {
    // read as usual
}

S3 support requires hardwood-s3 on the classpath. The compat layer loads it via reflection — if missing, a clear error message indicates which dependency to add.

Filter Pushdown

import static org.apache.parquet.filter2.predicate.FilterApi.*;
import org.apache.parquet.filter2.compat.FilterCompat;

FilterPredicate pred = and(
    gtEq(longColumn("id"), 100L),
    lt(doubleColumn("amount"), 500.0)
);

try (ParquetReader<Group> reader = ParquetReader.builder(new GroupReadSupport(), path)
        .withFilter(FilterCompat.get(pred))
        .build()) {
    // only rows from matching row groups are returned
}

Warning

This module provides its own type shims in the org.apache.parquet.* namespace. It cannot be used alongside parquet-java on the same classpath.