Big data processing with Apache Spark and Oracle Database

Big data processing with Apache
Spark and Oracle database
Martin Toshev

Who am I
Software consultant (CoffeeCupConsulting)
BG JUG board member (http://jug.bg)
(BG JUG is a 2018 Oracle Duke’s
choice award winner)

Agenda
• Apache Spark from an eagle’s eye
• Apache Spark capabilities
• Using Oracle RDBMS as a Spark datasource

Apache Spark from an Eagle’s eye

Highlights
• A framework for large-scale distributed data processing
• Originally in Scala but extended with Java, Python and R
• One of the most contributed
open source/Apache/GitHub projects with over 1400
contributors

Spark vs MapReduce
• Spark has been developed in order to address the
shortcomings of the MapReduce programming model
• In particular MapReduce is unsuitable for:
– real-time processing (suitable for batch processing of present data)
– operations not limited to the key-value format of data
– large data on a network
– online transaction processing
– graph processing
– sequential program execution

Spark vs Hadoop
• Spark is faster as it depends more on RAM usage and
tries to minimize disk IO (on the storage system)
• Spark however can still use Hadoop:
– as a storage engine (HDFS)
– as a compute engine (MapReduce or Hadoop YARN)
• Spark has pluggable storage and compute engine
architecture

Spark components
Spark Framework
Spark Core
Spark
Streaming
MLib GraphXSpark SQL

Spark architecture
SparkContext
(driver)
Cluster
manager
Worker
node
Worker
node
Worker
node
Spark application
(JAR)
Input data
sources
Output data
sources

Spark datasets
• The building block of Spark are RDDs (Resilient
Distributed Datasets)
• They are immutable collections of objects spread across
a Spark cluster and stored in RAM or on disk
• Created by means of distributed transformations
• Rebuilt on failure of a Spark node

Spark datasets
• The DataFrame API is a superset of RDDs introduced in
Spark 2.0
• The Dataset API provides a way to work with a
combination of RDDs and DataFrames
• The DataFrame API is preferred compared to RDDs due to
improved performance and more advanced operations

Spark datasets
List<Item> items = …;
SparkConf configuration = new
SparkConf().setAppName(“ItemsManager").setMaster("local");
JavaSparkContext context =
new JavaSparkContext(configuration);
JavaRDD<Item> itemsRDD = context.parallelize(items);

Spark transformations
map itemsRDD.map(i -> { i.setName(“phone”);
return i;});
filter itemsRDD.filter(i ->
i.getName().contains(“phone”))
flatMap itemsRDD.flatMap(i ->
Arrays.asList(i, i).iterator());
union itemsRDD.union(newItemsRDD);
intersection itemsRDD.intersection(newItemsRDD);
distinct itemsRDD.distinct()
cartesian itemsRDD.cartesian(otherDatasetRDD)

Spark transformations
groupBy pairItemsRDD = itemsRDD.mapToPair(i ->
new Tuple2(i.getType(), i));
modifiedPairItemsRDD =
pairItemsRDD.groupByKey();
reduceByKey pairItemsRDD = itemsRDD.mapToPair(o ->
new Tuple2(o.getType(), o));
modifiedPairItemsRDD =
pairItemsRDD.reduceByKey((o1, o2) ->
new Item(o1.getType(),
o1.getCount() + o2.getCount(),
o1.getUnitPrice())
);
• Other transformations include aggregateByKey,
sortByKey, join, cogroup …

Spark actions
• Spark actions are the terminal operations that produce
results from the transformations
• Actions are a way to communicate back from the
execution engine to the Spark driver instance

Spark actions
collect itemsRDD.collect()
reduce itemsRDD.map(i ->
i.getUnitPrice() * i.getCount()).
reduce((x, y) -> x + y);
count itemsRDD.count()
first itemsRDD.first()
take itemsRDD.take(4)
takeOrdered itemsRDD.takeOrdered(4, comparator)
foreach itemsRDD.foreach(System.out::println)
saveAsTextFile itemsRDD.saveAsTextFile(path)
saveAsObjectFile itemsRDD.saveAsObjectFile(path)

DataFrames/DataSets
• A dataframe can be created using an instance of the
org.apache.spark.sql.SparkSession class
• The DataFrame/DataSet APIs provide more advanced
operations and the capability to run SQL queries on the
data
itemsDS.createOrReplaceTempView(“items");
session.sql("SELECT * FROM items");

DataFrames/DataSets
• An existing RDD can be converted to a Spark dataframe:
• An RDD can be retrieved from a dataframe as well:
SparkSession session =
SparkSession.builder().appName("app").getOrCreate();
Dataset<Row> itemsDS =
session.createDataFrame(itemsRDD, Item.class);
itemsDS.rdd()

Spark data sources
• Spark can receive data from a variety of data sources in a
variety of ways (batching, real-time streaming)
• These datasources might be:
– files: Spark supports reading data from a variety of formats (JSON, CSV, Avro,
etc.)
– relational databases: using JDBC/ODBC driver Spark can extract data from an
RDBMS
– TCP sockets, messaging systems: using streaming capabilities of Spark data
can be read from messaging systems and raw TCP sockets

Spark data sources
• Spark provides support for operations on batch data or
real time data
• For real time data Spark provides two main APIs:
– Spark streaming is an older API working on RDDs
– Spark structured streaming is a newer API working on DataFrames/DataSets

Spark data sources
• Spark provides capabilities to plug-in additional data
sources not supported by Spark
• For streaming sources you can define your own custom
receivers

Spark streaming
• Data is divided into batches called Dstreams
(decentralized streams)
• Typical use case is the integration of Spark with
messaging systems such as Kafka, RabbitMQ and
ActiveMQ etc.
• Fault tolerance can be enabled in Spark Streaming
whereby data is stored in HDFS

Spark streaming
• To define a Spark stream you need to create a
JavaStreamingContext instance
SparkConf conf = new
SparkConf().setMaster("local[4]").setAppName("CustomerItems");
JavaStreamingContext jssc = new JavaStreamingContext(conf,
Durations.seconds(1));

Spark streaming
• Then a receiver can be created for the data:
– from sockets:
– from data directory:
– from RDD streams (for testing purposes):
jssc.socketTextStream("localhost", 7777);
jssc.textFileStream("... some data directory ...");
jssc.queueStream(... RDDs queue ... )

Spark streaming
• Then the data pipeline can be built using transformations
and actions on the streams
• Finally retrieval of data must be triggered from the
streaming context:
jssc.start();
jssc.awaitTermination();

Spark streaming
• Window streams can be created over stream data based
on two criteria:
– length of the window
– sliding interval for the windows
• Streaming datasets can also be joined with other
streaming or batch datasets

Spark structured streaming
• Newer streaming API working on DataSets/DataFrames:
• A schema can be specified on the streaming data using
the .schema(<schema>) method on the read stream
SparkSession context = SparkSession
.builder()
.appName("CustomerItems")
.getOrCreate();
Dataset<Row> lines = spark
.readStream()
.format("socket")
.option("host", "localhost")
.option("port", 7777)
.load();

Spark structured streaming
• Write sinks can also be used to write out streaming datasets:
• The following write sinks are provided by Spark:
- file
- Kafka
- foreach
- console (for testing purpose)
- memory (for testing purpose)
StreamingQuery query =
wordCounts.writeStream()
.outputMode("complete")
.format("console")
.start();
query.awaitTermination();

Clustering
• Spark supports the following cluster managers:
– Standalone scheduler (default)
– YARN
– Mesos
• Support for Kubernetes cluster manager is also
undergoing (experimental at present)

Using Oracle RDBMS
as a Spark datasource

Oracle RDBMS data source
• Spark supports retrieval of data through JDBC/ODBC
• Database driver must be supplied to the Spark classpath
(specified with the --driver-class-path) option
• For Oracle RDBMS that is the ojdbc driver

session.read()
.format("jdbc")
.option("url","jdbc:oracle:thin:@//127.0.0.1:1521/ORCL")
.option("dbtable", "items")
.option("user", "c##spark")
.option("password", "spark")
.load();

• You can use a variery of options when reading data from an
RDBMS using the jdbc format:
– query: a subquery that provides the possibility to limit retrieved data
– queryTimeout: specify the timeout for the JDBC query executed
against the RDBMS
• You can also save datasets to a table:
itemsDF.write().mode(org.apache.spark.sql.SaveMode.Append).
jdbc("jdbc:oracle:thin:@//127.0.0.1:1521/ORCL", “items",
prop);

Data processing options
• However the support provided by Spark is for batch
processing of data from the RDBMS …
• In many cases one might want to process data in a
streaming manner

• For stream processing of data from an Oracle RDBMS a
Spark instance may have to:
– process records as they are inserted in the RDBMS
Id Type OrderTime
1 Laptop 2019.11.05 11:55:05
2 Battery 2019.11.05 12:04:23
3 Headphones 2019.11.05 12:24:17
4 Laptop 2019.11.05 12:52:32

– process records on evenly-sized batches
Id Type OrderTime
1 Laptop 2019.11.05 11:55:05
2 Battery 2019.11.05 12:04:23
3 Headphones 2019.11.05 12:24:17
4 Laptop 2019.11.05 12:52:32

– process records on evenly-sized time intervals (record size may vary)
Id Type OrderTime
1 Laptop 2019.11.05 11:55:05
2 Battery 2019.11.05 12:04:23
3 Headphones 2019.11.05 12:24:17
4 Laptop 2019.11.05 12:52:32

– process batches of overlapping records using a sized window
Id Type OrderTime
1 Laptop 2019.11.05 11:55:05
2 Battery 2019.11.05 12:04:23
3 Headphones 2019.11.05 12:24:17
4 Laptop 2019.11.05 12:52:32

– processing of batches based on custom filter criteria
Id Type OrderTime
1 Laptop 2019.11.05 11:55:05
2 Battery 2019.11.05 12:04:23
3 Headphones 2019.11.05 12:24:17
4 Laptop 2019.11.05 12:52:32

• These can be achieved using the following mechanism:
– by duplicating writes over a streaming system such as Kafka
– via Spark streaming receiver that:
• buffer records (if a small delay is tolerable)
• creates an endpoint that an RDBMS trigger calls upon insertion
• listens for database changes using DCN (Database Change Notifications) via JDBC
(only pre-12c, DCN support dropped for PDBs as of 12c)

Summary
• Apache Spark is one of the most feature-rich and
developed big data processing frameworks
• Provides a mechanism to distribute load over a large
number of nodes using different cluster managers
• A great option for fast and scalable processing of data
from an Oracle RDBMS

Big data processing with Apache Spark and Oracle Database

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