I've been hunting around for a solution to this question.
It appears to me that there is no way to embed reading and writing Parquet format in a Java program without pulling in dependencies on HDFS and Hadoop. Is this correct?
I want to read and write on a client machine, outside of a Hadoop cluster.
I started to get excited about Apache Drill, but it appears that it must run as a separate process. What I need is an in-process ability to read and write a file using the Parquet format.
You can write parquet format out side hadoop cluster using java Parquet Client API.
Here is a sample code in java which writes parquet format to local disk.
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.apache.hadoop.fs.Path;
import org.apache.parquet.avro.AvroSchemaConverter;
import org.apache.parquet.avro.AvroWriteSupport;
import org.apache.parquet.hadoop.ParquetWriter;
import org.apache.parquet.hadoop.metadata.CompressionCodecName;
import org.apache.parquet.schema.MessageType;
public class Test {
void test() throws IOException {
final String schemaLocation = "/tmp/avro_format.json";
final Schema avroSchema = new Schema.Parser().parse(new File(schemaLocation));
final MessageType parquetSchema = new AvroSchemaConverter().convert(avroSchema);
final WriteSupport<Pojo> writeSupport = new AvroWriteSupport(parquetSchema, avroSchema);
final String parquetFile = "/tmp/parquet/data.parquet";
final Path path = new Path(parquetFile);
ParquetWriter<GenericRecord> parquetWriter = new ParquetWriter(path, writeSupport, CompressionCodecName.SNAPPY, BLOCK_SIZE, PAGE_SIZE);
final GenericRecord record = new GenericData.Record(avroSchema);
record.put("id", 1);
record.put("age", 10);
record.put("name", "ABC");
record.put("place", "BCD");
parquetWriter.write(record);
parquetWriter.close();
}
}
avro_format.json,
{
"type":"record",
"name":"Pojo",
"namespace":"com.xx.test",
"fields":[
{
"name":"id",
"type":[
"int",
"null"
]
},
{
"name":"age",
"type":[
"int",
"null"
]
},
{
"name":"name",
"type":[
"string",
"null"
]
},
{
"name":"place",
"type":[
"string",
"null"
]
}
]
}
Hope this helps.