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HBase and Spark

Apache Spark is a software framework that is used to process data in memory in a distributed manner, and is replacing MapReduce in many use cases.

Spark itself is out of scope of this document, please refer to the Spark site for more information on the Spark project and subprojects. This document will focus on 4 main interaction points between Spark and HBase. Those interaction points are:

Basic Spark
The ability to have an HBase Connection at any point in your Spark DAG.

Spark Streaming
The ability to have an HBase Connection at any point in your Spark Streaming application.

Spark Bulk Load
The ability to write directly to HBase HFiles for bulk insertion into HBase

SparkSQL/DataFrames
The ability to write SparkSQL that draws on tables that are represented in HBase.

The following sections will walk through examples of all these interaction points.

Basic Spark

This section discusses Spark HBase integration at the lowest and simplest levels. All the other interaction points are built upon the concepts that will be described here.

At the root of all Spark and HBase integration is the HBaseContext. The HBaseContext takes in HBase configurations and pushes them to the Spark executors. This allows us to have an HBase Connection per Spark Executor in a static location.

For reference, Spark Executors can be on the same nodes as the Region Servers or on different nodes, there is no dependence on co-location. Think of every Spark Executor as a multi-threaded client application. This allows any Spark Tasks running on the executors to access the shared Connection object.

HBaseContext Usage Example

This example shows how HBaseContext can be used to do a foreachPartition on a RDD in Scala:

val sc = new SparkContext("local", "test")
val config = new HBaseConfiguration()

...

val hbaseContext = new HBaseContext(sc, config)

rdd.hbaseForeachPartition(hbaseContext, (it, conn) => {
 val bufferedMutator = conn.getBufferedMutator(TableName.valueOf("t1"))
 it.foreach((putRecord) => {
. val put = new Put(putRecord._1)
. putRecord._2.foreach((putValue) => put.addColumn(putValue._1, putValue._2, putValue._3))
. bufferedMutator.mutate(put)
 })
 bufferedMutator.flush()
 bufferedMutator.close()
})

Here is the same example implemented in Java:

JavaSparkContext jsc = new JavaSparkContext(sparkConf);

try {
  List<byte[]> list = new ArrayList<>();
  list.add(Bytes.toBytes("1"));
  ...
  list.add(Bytes.toBytes("5"));

  JavaRDD<byte[]> rdd = jsc.parallelize(list);
  Configuration conf = HBaseConfiguration.create();

  JavaHBaseContext hbaseContext = new JavaHBaseContext(jsc, conf);

  hbaseContext.foreachPartition(rdd,
      new VoidFunction<Tuple2<Iterator<byte[]>, Connection>>() {
   public void call(Tuple2<Iterator<byte[]>, Connection> t)
        throws Exception {
    Table table = t._2().getTable(TableName.valueOf(tableName));
    BufferedMutator mutator = t._2().getBufferedMutator(TableName.valueOf(tableName));
    while (t._1().hasNext()) {
      byte[] b = t._1().next();
      Result r = table.get(new Get(b));
      if (r.getExists()) {
       mutator.mutate(new Put(b));
      }
    }

    mutator.flush();
    mutator.close();
    table.close();
   }
  });
} finally {
  jsc.stop();
}

All functionality between Spark and HBase will be supported both in Scala and in Java, with the exception of SparkSQL which will support any language that is supported by Spark. For the remaining of this documentation we will focus on Scala examples.

The examples above illustrate how to do a foreachPartition with a connection. A number of other Spark base functions are supported out of the box:

bulkPut
For massively parallel sending of puts to HBase

bulkDelete
For massively parallel sending of deletes to HBase

bulkGet
For massively parallel sending of gets to HBase to create a new RDD

mapPartition
To do a Spark Map function with a Connection object to allow full access to HBase

hbaseRDD
To simplify a distributed scan to create a RDD

For examples of all these functionalities, see the hbase-spark integration in the hbase-connectors repository (the hbase-spark connectors live outside hbase core in a related, Apache HBase project maintained, associated repo).

Spark Streaming

Spark Streaming is a micro batching stream processing framework built on top of Spark. HBase and Spark Streaming make great companions in that HBase can help serve the following benefits alongside Spark Streaming.

  • A place to grab reference data or profile data on the fly
  • A place to store counts or aggregates in a way that supports Spark Streaming's promise of only once processing.

The hbase-spark integration with Spark Streaming is similar to its normal Spark integration points, in that the following commands are possible straight off a Spark Streaming DStream.

bulkPut
For massively parallel sending of puts to HBase

bulkDelete
For massively parallel sending of deletes to HBase

bulkGet
For massively parallel sending of gets to HBase to create a new RDD

mapPartition
To do a Spark Map function with a Connection object to allow full access to HBase

hbaseRDD
To simplify a distributed scan to create a RDD

bulkPut Example with DStreams

Below is an example of bulkPut with DStreams. It is very close in feel to the RDD bulk put.

val sc = new SparkContext("local", "test")
val config = new HBaseConfiguration()

val hbaseContext = new HBaseContext(sc, config)
val ssc = new StreamingContext(sc, Milliseconds(200))

val rdd1 = ...
val rdd2 = ...

val queue = mutable.Queue[RDD[(Array[Byte], Array[(Array[Byte],
    Array[Byte], Array[Byte])])]]()

queue += rdd1
queue += rdd2

val dStream = ssc.queueStream(queue)

dStream.hbaseBulkPut(
  hbaseContext,
  TableName.valueOf(tableName),
  (putRecord) => {
   val put = new Put(putRecord._1)
   putRecord._2.foreach((putValue) => put.addColumn(putValue._1, putValue._2, putValue._3))
   put
  })

There are three inputs to the hbaseBulkPut function. The hbaseContext that carries the configuration broadcast information link to the HBase Connections in the executor, the table name of the table we are putting data into, and a function that will convert a record in the DStream into an HBase Put object.

Bulk Load

There are two options for bulk loading data into HBase with Spark. There is the basic bulk load functionality that will work for cases where your rows have millions of columns and cases where your columns are not consolidated and partitioned before the map side of the Spark bulk load process.

There is also a thin record bulk load option with Spark. This second option is designed for tables that have less then 10k columns per row. The advantage of this second option is higher throughput and less over-all load on the Spark shuffle operation.

Both implementations work more or less like the MapReduce bulk load process in that a partitioner partitions the rowkeys based on region splits and the row keys are sent to the reducers in order, so that HFiles can be written out directly from the reduce phase.

In Spark terms, the bulk load will be implemented around a Spark repartitionAndSortWithinPartitions followed by a Spark foreachPartition.

First lets look at an example of using the basic bulk load functionality

Bulk Loading Example

The following example shows bulk loading with Spark.

val sc = new SparkContext("local", "test")
val config = new HBaseConfiguration()

val hbaseContext = new HBaseContext(sc, config)

val stagingFolder = ...
val rdd = sc.parallelize(Array(
      (Bytes.toBytes("1"),
        (Bytes.toBytes(columnFamily1), Bytes.toBytes("a"), Bytes.toBytes("foo1"))),
      (Bytes.toBytes("3"),
        (Bytes.toBytes(columnFamily1), Bytes.toBytes("b"), Bytes.toBytes("foo2.b"))), ...

rdd.hbaseBulkLoad(TableName.valueOf(tableName),
  t => {
   val rowKey = t._1
   val family:Array[Byte] = t._2(0)._1
   val qualifier = t._2(0)._2
   val value = t._2(0)._3

   val keyFamilyQualifier= new KeyFamilyQualifier(rowKey, family, qualifier)

   Seq((keyFamilyQualifier, value)).iterator
  },
  stagingFolder.getPath)

val load = new LoadIncrementalHFiles(config)
load.doBulkLoad(new Path(stagingFolder.getPath),
  conn.getAdmin, table, conn.getRegionLocator(TableName.valueOf(tableName)))

The hbaseBulkLoad function takes three required parameters:

  1. The table name of the table we intend to bulk load too
  2. A function that will convert a record in the RDD to a tuple key value par. With the tuple key being a KeyFamilyQualifer object and the value being the cell value. The KeyFamilyQualifer object will hold the RowKey, Column Family, and Column Qualifier. The shuffle will partition on the RowKey but will sort by all three values.
  3. The temporary path for the HFile to be written out too

Following the Spark bulk load command, use the HBase's LoadIncrementalHFiles object to load the newly created HFiles into HBase.

Additional Parameters for Bulk Loading with Spark

You can set the following attributes with additional parameter options on hbaseBulkLoad.

  • Max file size of the HFiles
  • A flag to exclude HFiles from compactions
  • Column Family settings for compression, bloomType, blockSize, and dataBlockEncoding

Using Additional Parameters

val sc = new SparkContext("local", "test")
val config = new HBaseConfiguration()

val hbaseContext = new HBaseContext(sc, config)

val stagingFolder = ...
val rdd = sc.parallelize(Array(
      (Bytes.toBytes("1"),
        (Bytes.toBytes(columnFamily1), Bytes.toBytes("a"), Bytes.toBytes("foo1"))),
      (Bytes.toBytes("3"),
        (Bytes.toBytes(columnFamily1), Bytes.toBytes("b"), Bytes.toBytes("foo2.b"))), ...

val familyHBaseWriterOptions = new java.util.HashMap[Array[Byte], FamilyHFileWriteOptions]
val f1Options = new FamilyHFileWriteOptions("GZ", "ROW", 128, "PREFIX")

familyHBaseWriterOptions.put(Bytes.toBytes("columnFamily1"), f1Options)

rdd.hbaseBulkLoad(TableName.valueOf(tableName),
  t => {
   val rowKey = t._1
   val family:Array[Byte] = t._2(0)._1
   val qualifier = t._2(0)._2
   val value = t._2(0)._3

   val keyFamilyQualifier= new KeyFamilyQualifier(rowKey, family, qualifier)

   Seq((keyFamilyQualifier, value)).iterator
  },
  stagingFolder.getPath,
  familyHBaseWriterOptions,
  compactionExclude = false,
  HConstants.DEFAULT_MAX_FILE_SIZE)

val load = new LoadIncrementalHFiles(config)
load.doBulkLoad(new Path(stagingFolder.getPath),
  conn.getAdmin, table, conn.getRegionLocator(TableName.valueOf(tableName)))

Now lets look at how you would call the thin record bulk load implementation

Using thin record bulk load

val sc = new SparkContext("local", "test")
val config = new HBaseConfiguration()

val hbaseContext = new HBaseContext(sc, config)

val stagingFolder = ...
val rdd = sc.parallelize(Array(
      ("1",
        (Bytes.toBytes(columnFamily1), Bytes.toBytes("a"), Bytes.toBytes("foo1"))),
      ("3",
        (Bytes.toBytes(columnFamily1), Bytes.toBytes("b"), Bytes.toBytes("foo2.b"))), ...

rdd.hbaseBulkLoadThinRows(hbaseContext,
      TableName.valueOf(tableName),
      t => {
        val rowKey = t._1

        val familyQualifiersValues = new FamiliesQualifiersValues
        t._2.foreach(f => {
          val family:Array[Byte] = f._1
          val qualifier = f._2
          val value:Array[Byte] = f._3

          familyQualifiersValues +=(family, qualifier, value)
        })
        (new ByteArrayWrapper(Bytes.toBytes(rowKey)), familyQualifiersValues)
      },
      stagingFolder.getPath,
      new java.util.HashMap[Array[Byte], FamilyHFileWriteOptions],
      compactionExclude = false,
      20)

val load = new LoadIncrementalHFiles(config)
load.doBulkLoad(new Path(stagingFolder.getPath),
  conn.getAdmin, table, conn.getRegionLocator(TableName.valueOf(tableName)))

Note that the big difference in using bulk load for thin rows is the function returns a tuple with the first value being the row key and the second value being an object of FamiliesQualifiersValues, which will contain all the values for this row for all column families.

SparkSQL/DataFrames

The hbase-spark integration leverages DataSource API (SPARK-3247) introduced in Spark-1.2.0, which bridges the gap between simple HBase KV store and complex relational SQL queries and enables users to perform complex data analytical work on top of HBase using Spark. HBase Dataframe is a standard Spark Dataframe, and is able to interact with any other data sources such as Hive, Orc, Parquet, JSON, etc. The hbase-spark integration applies critical techniques such as partition pruning, column pruning, predicate pushdown and data locality.

To use the hbase-spark integration connector, users need to define the Catalog for the schema mapping between HBase and Spark tables, prepare the data and populate the HBase table, then load the HBase DataFrame. After that, users can do integrated query and access records in HBase tables with SQL query. The following illustrates the basic procedure.

Define catalog

def catalog = s"""{
       |"table":{"namespace":"default", "name":"table1"},
       |"rowkey":"key",
       |"columns":{
         |"col0":{"cf":"rowkey", "col":"key", "type":"string"},
         |"col1":{"cf":"cf1", "col":"col1", "type":"boolean"},
         |"col2":{"cf":"cf2", "col":"col2", "type":"double"},
         |"col3":{"cf":"cf3", "col":"col3", "type":"float"},
         |"col4":{"cf":"cf4", "col":"col4", "type":"int"},
         |"col5":{"cf":"cf5", "col":"col5", "type":"bigint"},
         |"col6":{"cf":"cf6", "col":"col6", "type":"smallint"},
         |"col7":{"cf":"cf7", "col":"col7", "type":"string"},
         |"col8":{"cf":"cf8", "col":"col8", "type":"tinyint"}
       |}
     |}""".stripMargin

Catalog defines a mapping between HBase and Spark tables. There are two critical parts of this catalog. One is the rowkey definition and the other is the mapping between table column in Spark and the column family and column qualifier in HBase. The above defines a schema for a HBase table with name as table1, row key as key and a number of columns (col1 - col8). Note that the rowkey also has to be defined in details as a column (col0), which has a specific cf (rowkey).

Save the DataFrame

case class HBaseRecord(
   col0: String,
   col1: Boolean,
   col2: Double,
   col3: Float,
   col4: Int,
   col5: Long,
   col6: Short,
   col7: String,
   col8: Byte)

object HBaseRecord
{
   def apply(i: Int, t: String): HBaseRecord = {
      val s = s"""row${"%03d".format(i)}"""
      HBaseRecord(s,
      i % 2 == 0,
      i.toDouble,
      i.toFloat,
      i,
      i.toLong,
      i.toShort,
      s"String$i: $t",
      i.toByte)
  }
}

val data = (0 to 255).map { i =>  HBaseRecord(i, "extra")}

sc.parallelize(data).toDF.write.options(
 Map(HBaseTableCatalog.tableCatalog -> catalog, HBaseTableCatalog.newTable -> "5"))
 .format("org.apache.hadoop.hbase.spark ")
 .save()

data prepared by the user is a local Scala collection which has 256 HBaseRecord objects. sc.parallelize(data) function distributes data to form an RDD. toDF returns a DataFrame. write function returns a DataFrameWriter used to write the DataFrame to external storage systems (e.g. HBase here). Given a DataFrame with specified schema catalog, save function will create an HBase table with 5 regions and save the DataFrame inside.

Load the DataFrame

def withCatalog(cat: String): DataFrame = {
  sqlContext
  .read
  .options(Map(HBaseTableCatalog.tableCatalog->cat))
  .format("org.apache.hadoop.hbase.spark")
  .load()
}
val df = withCatalog(catalog)

In 'withCatalog' function, sqlContext is a variable of SQLContext, which is the entry point for working with structured data (rows and columns) in Spark. read returns a DataFrameReader that can be used to read data in as a DataFrame. option function adds input options for the underlying data source to the DataFrameReader, and format function specifies the input data source format for the DataFrameReader. The load() function loads input in as a DataFrame. The date frame df returned by withCatalog function could be used to access HBase table, such as 4.4 and 4.5.

Language Integrated Query

val s = df.filter(($"col0" <= "row050" && $"col0" > "row040") ||
  $"col0" === "row005" ||
  $"col0" <= "row005")
  .select("col0", "col1", "col4")
s.show

DataFrame can do various operations, such as join, sort, select, filter, orderBy and so on. df.filter above filters rows using the given SQL expression. select selects a set of columns: col0, col1 and col4.

SQL Query

df.registerTempTable("table1")
sqlContext.sql("select count(col1) from table1").show

registerTempTable registers df DataFrame as a temporary table using the table name table1. The lifetime of this temporary table is tied to the SQLContext that was used to create df. sqlContext.sql function allows the user to execute SQL queries.

Others

Query with different timestamps

In HBaseSparkConf, four parameters related to timestamp can be set. They are TIMESTAMP, MIN_TIMESTAMP, MAX_TIMESTAMP and MAX_VERSIONS respectively. Users can query records with different timestamps or time ranges with MIN_TIMESTAMP and MAX_TIMESTAMP. In the meantime, use concrete value instead of tsSpecified and oldMs in the examples below.

The example below shows how to load df DataFrame with different timestamps. tsSpecified is specified by the user. HBaseTableCatalog defines the HBase and Relation relation schema. writeCatalog defines catalog for the schema mapping.

val df = sqlContext.read
      .options(Map(HBaseTableCatalog.tableCatalog -> writeCatalog, HBaseSparkConf.TIMESTAMP -> tsSpecified.toString))
      .format("org.apache.hadoop.hbase.spark")
      .load()

The example below shows how to load df DataFrame with different time ranges. oldMs is specified by the user.

val df = sqlContext.read
      .options(Map(HBaseTableCatalog.tableCatalog -> writeCatalog, HBaseSparkConf.MIN_TIMESTAMP -> "0",
        HBaseSparkConf.MAX_TIMESTAMP -> oldMs.toString))
      .format("org.apache.hadoop.hbase.spark")
      .load()

After loading df DataFrame, users can query data.

df.registerTempTable("table")
sqlContext.sql("select count(col1) from table").show

Native Avro support

The hbase-spark integration connector supports different data formats like Avro, JSON, etc. The use case below shows how spark supports Avro. Users can persist the Avro record into HBase directly. Internally, the Avro schema is converted to a native Spark Catalyst data type automatically. Note that both key-value parts in an HBase table can be defined in Avro format.

  1. Define catalog for the schema mapping:

    def catalog = s"""{
                    |"table":{"namespace":"default", "name":"Avrotable"},
                      |"rowkey":"key",
                      |"columns":{
                      |"col0":{"cf":"rowkey", "col":"key", "type":"string"},
                      |"col1":{"cf":"cf1", "col":"col1", "type":"binary"}
                      |}
                      |}""".stripMargin

    catalog is a schema for a HBase table named Avrotable. row key as key and one column col1. The rowkey also has to be defined in details as a column (col0), which has a specific cf (rowkey).

  2. Prepare the Data:

    object AvroHBaseRecord {
  val schemaString =
    s"""{"namespace": "example.avro",
        |   "type": "record",      "name": "User",
        |    "fields": [
        |        {"name": "name", "type": "string"},
        |        {"name": "favorite_number",  "type": ["int", "null"]},
        |        {"name": "favorite_color", "type": ["string", "null"]},
        |        {"name": "favorite_array", "type": {"type": "array", "items": "string"}},
        |        {"name": "favorite_map", "type": {"type": "map", "values": "int"}}
        |      ]    }""".stripMargin

  val avroSchema: Schema = {
    val p = new Schema.Parser
    p.parse(schemaString)
  }

  def apply(i: Int): AvroHBaseRecord = {
    val user = new GenericData.Record(avroSchema);
    user.put("name", s"name${"%03d".format(i)}")
    user.put("favorite_number", i)
    user.put("favorite_color", s"color${"%03d".format(i)}")
    val favoriteArray = new GenericData.Array[String](2, avroSchema.getField("favorite_array").schema())
    favoriteArray.add(s"number${i}")
    favoriteArray.add(s"number${i+1}")
    user.put("favorite_array", favoriteArray)
    import collection.JavaConverters._
    val favoriteMap = Map[String, Int](("key1" -> i), ("key2" -> (i+1))).asJava
    user.put("favorite_map", favoriteMap)
    val avroByte = AvroSedes.serialize(user, avroSchema)
    AvroHBaseRecord(s"name${"%03d".format(i)}", avroByte)
  }
}

val data = (0 to 255).map { i =>
    AvroHBaseRecord(i)
}

    schemaString is defined first, then it is parsed to get avroSchema. avroSchema is used to generate AvroHBaseRecord. data prepared by users is a local Scala collection which has 256 AvroHBaseRecord objects.

  3. Save DataFrame:

    sc.parallelize(data).toDF.write.options(
    Map(HBaseTableCatalog.tableCatalog -> catalog, HBaseTableCatalog.newTable -> "5"))
    .format("org.apache.spark.sql.execution.datasources.hbase")
    .save()

    Given a data frame with specified schema catalog, above will create an HBase table with 5 regions and save the data frame inside.

  4. Load the DataFrame

    def avroCatalog = s"""{
            |"table":{"namespace":"default", "name":"avrotable"},
            |"rowkey":"key",
            |"columns":{
              |"col0":{"cf":"rowkey", "col":"key", "type":"string"},
              |"col1":{"cf":"cf1", "col":"col1", "avro":"avroSchema"}
            |}
          |}""".stripMargin

def withCatalog(cat: String): DataFrame = {
    sqlContext
        .read
        .options(Map("avroSchema" -> AvroHBaseRecord.schemaString, HBaseTableCatalog.tableCatalog -> avroCatalog))
        .format("org.apache.spark.sql.execution.datasources.hbase")
        .load()
}
val df = withCatalog(catalog)

    In withCatalog function, read returns a DataFrameReader that can be used to read data in as a DataFrame. The option function adds input options for the underlying data source to the DataFrameReader. There are two options: one is to set avroSchema as AvroHBaseRecord.schemaString, and one is to set HBaseTableCatalog.tableCatalog as avroCatalog. The load() function loads input in as a DataFrame. The date frame df returned by withCatalog function could be used to access the HBase table.

  5. SQL Query

    df.registerTempTable("avrotable")
val c = sqlContext.sql("select count(1) from avrotable").

    After loading df DataFrame, users can query data. registerTempTable registers df DataFrame as a temporary table using the table name avrotable. sqlContext.sql function allows the user to execute SQL queries.

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Thrift API and Filter Language

Apache Thrift is a cross-platform, cross-language development framework. HBase includes a Thrift API and filter language. The Thrift API relies on client and server processes.

Apache HBase Coprocessors

The coprocessor framework provides mechanisms for running your custom code directly on the RegionServers managing your data.

On this page

Basic Spark
HBaseContext Usage Example
Spark Streaming
bulkPut Example with DStreams
Bulk Load
Bulk Loading Example
Additional Parameters for Bulk Loading with Spark
Using Additional Parameters
Using thin record bulk load
SparkSQL/DataFrames
Define catalog
Save the DataFrame
Load the DataFrame
Language Integrated Query
SQL Query
Others
Query with different timestamps
Native Avro support