Quick start

SBT

libraryDependencies ++= Seq(
  "com.github.mjakubowski84" %% "parquet4s-core" % "2.20.0",
  "org.apache.hadoop" % "hadoop-client" % yourHadoopVersion
)

Mill

def ivyDeps = Agg(
  ivy"com.github.mjakubowski84::parquet4s-core:2.20.0",
  ivy"org.apache.hadoop:hadoop-client:$yourHadoopVersion"
)

import com.github.mjakubowski84.parquet4s.{ ParquetReader, ParquetWriter, Path }

case class User(userId: String, name: String, created: java.sql.Timestamp)

val users: Iterable[User] = Seq(
  User("1", "parquet", new java.sql.Timestamp(1L))
)
val path = Path("path/to/local/file.parquet")

// writing
ParquetWriter.of[User].writeAndClose(path, users)

// reading
val parquetIterable = ParquetReader.as[User].read(path)
try {
  parquetIterable.foreach(println)
} finally parquetIterable.close()

AWS S3

In order to connect to AWS S3 you need to define one more dependency:

"org.apache.hadoop" % "hadoop-aws" % yourHadoopVersion

Next, the most common way is to define following environmental variables:

export AWS_ACCESS_KEY_ID=my.aws.key
export AWS_SECRET_ACCESS_KEY=my.secret.key

You may need to set some configuration properties to access your storage, e.g. fs.s3a.path.style.access. Please follow documentation of Hadoop AWS for more details and troubleshooting.

Passing Hadoop Configs Programmatically

File system configs for S3, GCS, Hadoop, etc. can also be set programmatically to the ParquetReader and ParquetWriter by passing the Configuration to the ParqetReader.Options and ParquetWriter.Options case classes.

import com.github.mjakubowski84.parquet4s.{ ParquetReader, ParquetWriter, Path }
import org.apache.parquet.hadoop.metadata.CompressionCodecName
import org.apache.hadoop.conf.Configuration

case class User(userId: String, name: String, created: java.sql.Timestamp)

val users: Iterable[User] = Seq(
  User("1", "parquet", new java.sql.Timestamp(1L))
)

val writerOptions = ParquetWriter.Options(
  compressionCodecName = CompressionCodecName.SNAPPY,
  hadoopConf = new Configuration()
)

ParquetWriter
  .of[User]
  .options(writerOptions)
  .writeAndClose(Path("path/to/local/file.parquet"), users)