Tag: Pivotal

Apache Spark for Big Analytics (Updated for Spark Summit and Release 1.0.1)

Updated and bumped July 10, 2014.

For a powerpoint version on Slideshare, go here.

Introduction

Apache Spark is an open source distributed computing framework for advanced analytics in Hadoop.  Originally developed as a research project at UC Berkeley’s AMPLab, the project achieved incubator status in Apache in June 2013 and top-level status in February 2014.  According to one analyst, Apache Spark is among the five key Big Data technologies, together with cloud, sensors, AI and quantum computing.

Organizations seeking to implement advanced analytics in Hadoop face two key challenges.  First, MapReduce 1.0 must persist intermediate results to disk after each pass through the data; since most advanced analytics tasks require multiple passes through the data, this requirement adds latency to the process.

A second key challenge is the plethora of analytic point solutions in Hadoop.  These include, among others, Mahout for machine learning; Giraph, and GraphLab for graph analytics; Storm and S4 for streaming; or Hive, Impala and Stinger for interactive queries.  Multiple independently developed analytics projects add complexity to the solution; they pose support and integration challenges.

Spark directly addresses these challenges.  It supports distributed in-memory processing, so developers can write iterative algorithms without writing out a result set after each pass through the data.  This enables true high performance advanced analytics; for techniques like logistic regression, project sponsors report runtimes in Spark 100X faster than what they are able to achieve with MapReduce.

Second, Spark offers an integrated framework for analytics, including:

A closely related project, Shark, supports fast queries in Hadoop.  Shark runs on Spark and the two projects share a common heritage, but Shark is not currently included in the Apache Spark project.  The Spark project expects to absorb Shark into Spark SQL as of Release 1.1 in August 2014.

Spark’s core is an abstraction layer called Resilient Distributed Datasets, or RDDs.  RDDs are read-only partitioned collections of records created through deterministic operations on stable data or other RDDs.  RDDs include information about data lineage together with instructions for data transformation and (optional) instructions for persistence.  They are designed to be fault tolerant, so that if an operation fails it can be reconstructed.

For data sources, Spark works with any file stored in HDFS, or any other storage system supported by Hadoop (including local file systems, Amazon S3, Hypertable and HBase).  Hadoop supports text files, SequenceFiles and any other Hadoop InputFormat.  Through Spark SQL, the Spark user can import relational data from Hive tables and Parquet files.

Analytic Features

Spark’s machine learning library, MLLib, is rapidly growing.   In Release 1.0.0 (the latest release) it includes:

  • Linear regression
  • Logistic regression
  • k-means clustering
  • Support vector machines
  • Alternating least squares (for collaborative filtering)
  • Decision trees for classification and regression
  • Naive Bayes classifier
  • Distributed matrix algorithms (including Singular Value Decomposition and Principal Components Analysis)
  • Model evaluation functions
  • L-BFGS optimization primitive

Linear regression, logistic regression and support vector machines all use a gradient descent optimization algorithm, with options for L1 and L2 regularization.  MLLib is part of a larger machine learning project (MLBase), which includes an API for feature extraction and an optimizer (currently in development with planned release in 2014).

In March, the Apache Mahout project announced that it will shift development from MapReduce to Spark.  Mahout no longer accepts projects built on MapReduce; future projects leverage a DSL for linear algebra implemented on Spark.  The Mahout team will maintain existing MapReduce projects.  There is as yet no announced roadmap to migrate existing projects from MapReduce to Spark.

Spark SQL, currently in Alpha release, supports SQL, HiveQL, and Scala. The foundation of Spark SQL is a type of RDD, SchemaRDD, an object similar to a table in a relational database. SchemaRDDs can be created from an existing RDD, Parquet file, a JSON dataset, or by running HiveQL against data stored in Apache Hive.

GraphX, Spark’s graph engine, combines the advantages of data-parallel and graph-parallel systems by efficiently expressing graph computation within the Spark framework.  It enables users to interactively load, transform, and compute on massive graphs.  Project sponsors report performance comparable to Apache Giraph, but in a fault tolerant environment that is readily integrated with other advanced analytics.

Spark Streaming offers an additional abstraction called discretized streams, or DStreams.  DStreams are a continuous sequence of RDDs representing a stream of data.  The user creates DStreams from live incoming data or by transforming other DStreams.  Spark receives data, divides it into batches, then replicates the batches for fault tolerance and persists them in memory where they are available for mathematical operations.

Currently, Spark supports programming interfaces for Scala, Java and Python;  MLLib algorithms support sparse feature vectors in all three languages.  For R users, Berkeley’s AMPLab released a developer preview of SparkR in January 2014

There is an active and growing developer community for Spark: 83 developers contributed to Release 0.9, and 117 developers contributed to Release 1.0.0.  In the past six months, developers contributed more commits to Spark than to all of the other Apache analytics projects combined.   In 2013, the Spark project published seven double-dot releases, including Spark 0.8.1 published on December 19; this release included YARN 2.2 support, high availability mode for cluster management, performance optimizations and improvements to the machine learning library and Python interface.  So far in 2014, the Spark team has released 0.9.0 in February; 0.9.1, a maintenance release, in April; and 1.0.0 in May.

Release 0.9 includes Scala 2.10 support, a configuration library, improvements to Spark Streaming, the Alpha release for GraphX, enhancements to MLLib and many other enhancements).  Release 1.0.0 features API stability, integration with YARN security, operational and packaging improvements, the Alpha release of Spark SQL, enhancements to MLLib, GraphX and Streaming, extended Java and Python support, improved documentation and many other enhancements.

Distribution

Spark is now available in every major Hadoop distribution.  Cloudera announced immediate support for Spark in February 2014; Cloudera partners with Databricks.  (For more on Cloudera’s support for Spark, go here).  In April, MapR announced that it will distribute Spark; Hortonworks and Pivotal followed in May.

Hortonworks’ approach to Spark focuses more narrowly on its machine learning capabilities, as the firm continues to promote Storm for streaming analytics and Hive for SQL.

IBM’s commitment to Spark is unclear.  While BigInsights is a certified Spark distribution and IBM was a Platinum sponsor of the 2014 Spark Summit, there are no references to Spark in BigInsights marketing and technical materials.

In May, NoSQL database vendor Datastax announced plans to integrate Apache Cassandra with the Spark core engine.  Datastax will partner with Databricks on this project; availability expected summer 2014.

At the 2014 Spark Summit, SAP announced its support for Spark.  SAP offers what it characterizes as a “smart integration”, which appears to represent Spark objects in HANA as virtual tables.

On June 26, Databricks announced its Certified Spark Distribution program, which recognizes vendors committed to supporting the Spark ecosystem.   The first five vendors certified under this program are Datastax, Hortonworks, IBM, Oracle and Pivotal.

At the 2014 Spark Summit, Cloudera, Dell and Intel announced plans to deliver a Spark appliance.

Ecosystem

In April, Databricks announced that it licensed the Simba ODBC engine, enabling BI platforms to interface with Spark.

Databricks offers a certification program for Spark; participants currently include:

In May, Databricks and Concurrent Inc announced a strategic partnership.  Concurrent plans to add Spark support to its Cascading development environment for Hadoop.

Community

In December, the first Spark Summit attracted more than 450 participants from more than 180 companies.  Presentations covered a range of applications such as neuroscience, audience expansion, real-time network optimization and real-time data center management, together with a range of technical topics. (To see the presentations, search YouTube for ‘Spark Summit 2013’, or go here).

The 2014 Spark Summit was be held June 30 through July 2 in San Francisco.  The event sold out at more than a thousand participants.  For a summary, see this post.

There is a rapidly growing list of Spark Meetups, including:

Now available for pre-order on Amazon:

Finally, this series of videos provides some good basic knowledge about Spark.

Strata Report: Advanced Analytics in Hadoop

Here is a quick review of the capabilities for advanced analytics in Hadoop for five vendors at the recent Strata NYC conference:

0XData

Product(s)

  • H20 (open source project)
  • h2o (R package)

Description

Smart people from Stanford with VC backing and a social media program.   Services business model with open source software.  H20 is an open source library of algorithms designed for deployment in Hadoop or free-standing clusters;  aggressive vision, but currently available functionality limited to GLM, k-Means, Random Forests.   Update: 0xData just announced H20 2.0, which includes Distributed Trees and Regression, such as Gradient Boosting Machine (GBM), Random Forest (RF), Generalized Linear Modeling (GLM), k-Means and Principal Component Analysis (PCA).  They also claim to run “100X faster than other predictive analytics providers”, although this claim is not supported by evidence.  R users can interface through h2o package.  Limited customer base.  Partners with Cloudera and MapR.

Key Points

  • True open source model
  • Comprehensive roadmap
  • Limited functionality
  • Limited user base
  • Performance claims undocumented

Alpine Data Labs

Product(s)

  • Alpine 2.8

Description

Alpine targets a business user persona with a visual workflow-oriented interface (comparable to SAS Enterprise Miner or SPSS Modeler).   Supports a reasonably broad range of analytic features.  Claims to run “in” a number of databases and Hadoop distributions, but company is opaque about how this works.  (Appears to be SQL/HiveQL push-down).   In practice, most customers seem to use Alpine with Greenplum.  Thin sales and customer base relative to claimed feature mix suggests uncertainty about product performance and stability.  Partners with Pivotal, Cloudera and MapR.

Key Points

  • Reasonable option for users already committed to Greenplum Database
  • Limited partner and user ecosystem
  • Performance and stability should be vetted thoroughly in POC

Oracle

Product(s)

Description

Oracle R Distribution (ORD) is a free distribution of R with bug fixes and performance enhancements; Oracle R Enterprise is a supported version of ORD with additional enhancements (detailed below).

Oracle Advanced Analytics (an option of Oracle Database Enterprise Edition) bundles Oracle Data Mining, a distributed data mining engine that runs in Oracle Database, and Oracle R Enterprise.   Oracle Advanced Analytics provides an R to SQL transparency layer that maps R functions and algorithms to native in-database SQL equivalents.  When in-database equivalents are not available, Oracle Advanced Analytics can run R commands under embedded R mode.

Oracle Connection to Hadoop  is an R interface to Hadoop; it enables the user to write MapReduce tasks in R and interface with Hive.  As of ORCH 2.1.0, there is also a fairly rich collection of machine learning algorithms for supervised and unsupervised learning that can be pushed down into Hadoop.

Key Points

  • Good choice for Oracle-centric organizations
  • Oracle Data Mining is a mature product with an excellent user interface
  • Must move data from Hadoop to Oracle Database to leverage OAA
  • Hadoop push-down from R requires expertise in MapReduce

SAS

Products

  • SAS/ACCESS Interface to Hadoop
  • SAS Scoring Accelerator for Cloudera
  • SAS Visual Analytics/SAS LASR Server
  • SAS High Performance Analytics Server

Description

SAS/ACCESS Interface to Hadoop enables SAS users to pass Hive, Pig or MapReduce commands to Hadoop through a connection and move the results back to the SAS server.   With SAS/ACCESS you can haul your data out of Hadoop, plug it into SAS and use a bunch of other SAS products, but that architecture is pretty much a non-starter for most Strata attendees.   Update:  SAS has announced SAS/ACCESS for Impala.

Visual Analytics is a Tableau-like visualization tool with limited predictive analytic capabilities; LASR Server is the in-memory back end for Visual Analytics.  High Performance Analytics is a suite of distributed in-memory analytics.   LASR Server and HPA Server can be co-located in a Hadoop cluster, but require special hardware.  Partners with Cloudera and Hortonworks.

Key Points

  • Legacy SAS connects to Hadoop, does not run in Hadoop
  • SAS/ACCESS users must know exact Hive, Pig or MapReduce syntax
  • Visual Analytics cannot work with “raw” data in Hadoop
  • Minimum hardware requirements for LASR and HPA significantly exceed standard Hadoop worker node specs
  • High TCO, proprietary architecture for all SAS products

Skytree

Product(s)

  • Skytree Server

Description

Academic machine learning project (FastLab, at Georgia Tech); with VC backing, launched as commercial software vendor January 2013.  Server-based technology, can connect to a range of data sources, including Hadoop.  Programming interface; claims ability to run from R, Weka, C++ and Python.  Good library of algorithms.  Partners with Cloudera, Hortonworks, MapR.  Skytree is opaque about technology and performance claims.

Key Points

  • Limited customer base, no announced sales since company launch
  • Hadoop integration is a connection, not “inside” architecture
  • Performance claims should be carefully vetted

SAS and Hadoop

SAS’ recent announcement of an alliance with Hortonworks marks a good opportunity to summarize SAS’ Hadoop capabilities.    Analytic enterprises are increasingly serious about using Hadoop as an analytics platform; organizations with significant “sunk” investment in SAS are naturally interested in understanding SAS’ ability to work with Hadoop.

Prior to January, 2012, a search for the words “Hadoop” or “MapReduce” returned no results on the SAS marketing and support websites, which says something about SAS’ leadership in this area.  In March 2012, SAS announced support for Hadoop connectivity;  since then, SAS has gradually expanded the features it supports with Hadoop.

As of today, there are four primary ways that a SAS user can leverage Hadoop:

Let’s take a look at each option.

“Legacy SAS” is a convenient term for Base SAS, SAS/STAT and various packages (GRAPH, ETS, OR, etc) that are used primarily from a programming interface.  SAS/ACCESS Interface to Hadoop provides SAS users with the ability to connect to Hadoop, pass through Hive, Pig or MapReduce commands, extract data and bring it back to the SAS server for further processing.  It works in a manner similar to all of the SAS/ACCESS engines, but there are some inherent differences between Hadoop and commercial databases that impact the SAS user.  For more detailed information, read the manual.

SAS/ACCESS also supports six “Hadoop-enabled” PROCS (FREQ, MEANS, RANK, REPORT, SUMMARY, TABULATE); for perspective, there are some 300 PROCs in Legacy SAS, so there are ~294 PROCs that do not run inside Hadoop.  If all you need to do is run frequency distributions, simple statistics and summary reports then SAS offers everything you need for analytics in Hadoop.  If that is all you want to do, of course, you can use Datameer or Big Sheets and save on SAS licensing fees.

A SAS programmer who is an expert in Hive, Pig or MapReduce can accomplish a lot with this capability, but the SAS software provides minimal support and does not “translate” SAS DATA steps.  (In my experience, most SAS users are not experts in SQL, Hive, Pig or MapReduce).  SAS users who work with the SAS Pass-Through SQL Facility know that in practice one must submit explicit SQL to the database, because “implicit SQL” only works in certain circumstances (which SAS does not document);  if SAS cannot implicitly translate a DATA Step into SQL/HiveQL, it copies the data back to the SAS server –without warning — and performs the operation there.

SAS/ACCESS Interface to Hadoop works with HiveQL, but the user experience is similar to working with SQL Pass-Through.  Limited as “implicit HiveQL” may be, SAS does not claim to offer “implicit Pig” or “implicit MapReduce”.   The bottom line is that since the user needs to know how to program in Hive, Pig or MapReduce to use SAS/ACCESS Interface to Hadoop, the user might as well submit your jobs directly to Hive, Pig or MapReduce and save on SAS licensing fees.

SAS has not yet released the SAS/ACCESS Interface to Cloudera Impala, which it announced in October for December 2013 availability.

SAS Scoring Accelerator enables a SAS Enterprise Miner user to export scoring models to relational databases, appliances and (most recently) to Cloudera.  Scoring Accelerator only works with SAS Enterprise Miner, and it doesn’t work with “code nodes” — which means that in practice must customers must rebuild existing predictive models to take advantage of the product.   Customers who already use SAS Enterprise Miner, can export the models in PMML and use them in any PMML-enabled database or decision engine and spend less on SAS licensing fees.

Which brings us to the two relatively new in-memory products, SAS Visual Analytics/SAS LASR Server and SAS High Performance Analytics Server.   These products were originally designed to run in specially constructed appliances from Teradata and Greenplum; with SAS 9.4 they are supported in a co-located Hadoop configuration that SAS calls a Distributed Alongside-HDFS architecture.  That means LASR and HPA can be installed on Hadoop nodes next to HDFS and, in theory, distributed throughout the Hadoop cluster with one instance of SAS on each node.

That looks good on a PowerPoint, but feedback from customers who have attempted to deploy SAS HPA in Hadoop is negative.  In a Q&A session at Strata NYC, SAS VP Paul Kent commented that it is possible to run SAS HPA on commodity hardware as long as you don’t want to run MapReduce jobs at the same time.  SAS’ hardware partners recommend 16-core machines with 256-512GB RAM for each HPA/LASR node; that hardware costs five or six times as much as a standard Hadoop worker node machine.  Since even the most committed SAS customer isn’t willing to replace the hardware in a 400-node Hadoop cluster, most customers will stand up a few high-end machines next to the Hadoop cluster and run the in-memory analytics in what SAS calls Asymmetric Distributed Alongside-HDFS mode.  This architecture adds latency to runtime performance, since data must be copied from the HDFS Data Nodes to the Analytic Nodes.

While HPA can work directly with HDFS data, VA/LASR Server requires data to be in SAS’ proprietary SASHDAT format.   To import the data into SASHDAT, you will need to license SAS Data Integration Server.

A single in-memory node supported by a 16-core/256GB can load a 75-100GB table, so if you’re working with a terabyte-sized dataset you’re going to need 10-12 nodes.   SAS does not publicly disclose its software pricing, but customers and partners report quotes with seven zeros for similar configurations.  Two years into General Availability, SAS has no announced customers for SAS High Performance Analytics.

SAS seems to be doing a little better selling SAS VA/LASR Server; they have a big push on in 2013 to sell 2,000 copies of VA and heavily promote a one node version on a big H-P machine for $100K.  Not sure how they’re doing against that target of 2,000 copies, but they have announced thirteen sales this year to smaller SAS-centric organizations, all but one outside the US.

While SAS has struggled to implement its in-memory software in Hadoop to date,  YARN and MapReduce 2.0 will make it much easier to run non-MapReduce applications in Hadoop.  Thus, it is not surprising that Hortonworks’ announcement of the SAS alliance coincides with the release of HDP 2.0, which offers production support for YARN.