ENTRIES TAGGED "realtime"
The inaugural Spark Summit will feature a wide variety of real-world applications
When an interesting piece of big data technology gets introduced, early1 adopters tend to focus on technical features and capabilities. Applications get built as companies develop confidence that it’s reliable and that it really scales to large data volumes. That seems to be where Spark is today. With over 90 contributors from 25 companies, it has one of the largest developer communities among big data projects (second only to Hadoop MapReduce).
I recently became an advisor to Databricks (a startup commercializing Spark) and a member of the program committee for the inaugural Spark Summit. As I pored over submissions to Spark’s first community gathering, I learned how companies have come to rely on Spark, Shark, and other components of the Berkeley Data Analytics Stack (BDAS). Spark is at that stage where companies are deploying it, and the upcoming Spark Summit in San Francisco will showcase many real-world applications. These applications cut across many domains including advertising, marketing, finance, and academic/scientific research, but can generally be grouped into the following categories:
Data processing workflows: ETL and Data Wrangling
Many companies rely on a wide variety of data sources for their analytic products. That means cleaning, transforming, and fusing (unstructured) external data with internal data sources. Many companies – particularly startups – use Spark for these types of data processing workflows. There are even companies that have created simple user interfaces that open up batch data processing tasks to non-programmers.
Tools for unlocking big data continue to get simpler
Here are a few observations based on conversations I had during the just concluded Strata NYC conference.
Interactive query analysis on Hadoop remains a hot area
A recent O’Reilly survey confirmed SQL is an important skill for data scientists. A year after the launch of Impala, quite a few attendees I spoke with remained interested in the progress of SQL-on-Hadoop solutions. A trio from Hortonworks gave an update on recent improvements and changes to Hive1. A sign that Impala is gaining traction, Greg Rahn’s talk on Practical Performance Tuning for Impala was one of the best attended sessions in the conference. Ditto for a sponsored session on Kognitio’s latest features.
Existing SQL-on-Hadoop solutions require that users define a schema – an additional step given that a lot of data is increasingly in key-value or JSON format. In his talk Hadapt co-founder Daniel Abadi highlighted a solution2 that lets users query complex data types (Hadapt reserializes complex data types to speed up joins). I expect other SQL-on-Hadoop solutions to also offer query support for complex data types in the near future.
Empowering business users
With its launch at the conference, ClearStory joins Platfora and Datameer in the business analytics space. Each company builds tools that lets business users wade through large amounts of data, while emphasizing different areas. Platfora is for interactive visual analysis of massive data sets, while Datameer connects to many data sources (not just Hadoop), has started offering analytics, and can run on a laptop or cluster. Built primarily on the Berkeley stack (BDAS), ClearStory’s interesting platform encourages collaboration and simplifies data harmonization (fusing disparate data sources is a common bottleneck for business users). For organizations willing to tag and describe their data sets, Microsoft unveiled a tool that lets users query data using natural language (UK startup NeutrinoBI uses a similar “search interface”).
Volume, variety, velocity, and a rare peek inside sponsored search advertising at Google
The $35B merger of Omnicom and Publicis put the convergence of Big Data and Advertising1 in the front pages of business publications. Adtech2 companies have long been at the forefront of many data technologies, strategies, and techniques. By now it’s well-known that many impressive large scale, realtime analytics systems in production, support3 advertising. A lot of effort has gone towards accurately predicting and measuring click-through rates, so at least for online advertising, data scientists and data engineers have gone a long way towards addressing4 the famous “but we don’t know which half” line.
The industry has its share of problems: privacy & creepiness come to mind, and like other technology sectors adtech has its share of “interesting” patent filings (see for example here, here, here). With so many companies dependent on online advertising, some have lamented the industry’s hold5 on data scientists. But online advertising does offer data scientists and data engineers lots of interesting technical problems to work on, many of which involve the deployment (and creation) of open source tools for massive amounts of data.
Hadoop moves from batch to near realtime: next up, placing streaming data in context
Simple example of a near realtime app built with Hadoop and HBase
Over the past year Hadoop emerged from its batch processing roots and began to take on interactive and near realtime applications. There are numerous examples that fall under these categories, but one that caught my eye recently is a system jointly developed by China Mobile Guangdong (CMG) and Intel1. It’s an online system that lets CMG’s over 100 million subscribers2 access and pay their bills, and examine their CDR’s (call detail records) in near realtime.
A service for providing detailed billing information is an important customer touch point. Repeated/extended downtimes and data errors could seriously tarnish CMG’s image. CMG needed a system that could scale to their current (and future) data volumes, while providing the low-latency responses consumers have come to expect from online services. Scalability, price and open source3 were important criteria in persuading the company to choose a Hadoop-based solution over4 MPP data warehouses.
In the system it co-developed with Intel, CMG stores detailed subscriber billing records in HBase. This amounts to roughly 30 TB/month, but since the service lets users browse up to six months of billing data it provides near realtime query results on much larger amounts of data. There are other near realtime applications built from Hadoop components (notably the continuous compute system at Yahoo!), that handle much larger data sets. But what I like about the CMG example is that it’s an application that most people understand right away (a detailed billing lookup system), and it illustrates that the Hadoop ecosystem has grown beyond batch processing.
Besides powering their online billing lookup service, CMG uses its Hadoop platform for analytics. Data from multiple sources (including phone device preferences, usage patterns, and cell tower performance) are used to compute customer segments and targeted promotions. Over time, Hadoop’s ability to handle large amounts of unstructured data opens up other data sources that can potentially improve CMG’s current analytic models.
Contextualize: Streaming and Perpetual Analytics
This leads me to something “realtime” systems are beginning to do: placing streaming data in context. Streaming analytics operates over fixed time windows and is used to identify “top k” trending items, heavy-hitters, and distinct items. Perpetual analytics takes what you’re observing now and places it in the context of what you already know. As much as companies appreciate metrics produced by streaming engines, they also want to understand how “realtime observations” affect their existing knowledge base.
The simplest and quickest way to mine your data is to deploy efficient algorithms designed to answer key questions at scale.
For many organizations real-time1 analytics entails complex event processing systems (CEP) or newer distributed stream processing frameworks like Storm, S4, or Spark Streaming. The latter have become more popular because they are able to process massive amounts of data, and fit nicely with Hadoop and other cluster computing tools. For these distributed frameworks peak volume is function of network topology/bandwidth and the throughput of the individual nodes.
Scaling up machine-learning: Find efficient algorithms
Faced with having to crunch through a massive data set, the first thing a machine-learning expert will try to do is devise a more efficient algorithm. Some popular approaches involve sampling, online learning, and caching. Parallelizing an algorithm tends to be lower on the list of things to try. The key reason is that while there are algorithms that are embarrassingly parallel (e.g., naive bayes), many others are harder to decouple. But as I highlighted in a recent post, efficient tools that run on single servers can tackle large data sets. In the machine-learning context recent examples2 of efficient algorithms that scale to large data sets, can be found in the products of startup SkyTree.
Barlow's distilled insights regarding the ever evolving definition of real time big data analytics
During a break in between offsite meetings that Edd and I were attending the other day, he asked me, “did you read the Barlow piece?”
“Umm, no.” I replied sheepishly. Insert a sidelong glance from Edd that said much without saying anything aloud. He’s really good at that.
In my utterly meager defense, Mike Loukides is the editor on Mike Barlow’s Real-Time Big Data Analytics: Emerging Architecture. As Loukides is one of the core drivers behind O’Reilly’s book publishing program and someone who I perceive to be an unofficial boss of my own choosing, I am not really inclined to worry about things that I really don’t need to worry about. Then I started getting not-so-subtle inquiries from additional people asking if I would consider reviewing the manuscript for the Strata community site. This resulted in me emailing Loukides for a copy and sitting in a local cafe on a Sunday afternoon to read through the manuscript.
Shark is 100X faster than Hive for SQL, and 100X faster than Hadoop for machine-learning
Hadoop’s strength is in batch processing, MapReduce isn’t particularly suited for interactive/adhoc queries. Real-time1 SQL queries (on Hadoop data) are usually performed using custom connectors to MPP databases. In practice this means having connectors between separate Hadoop and database clusters. Over the last few months a number of systems that provide fast SQL access within Hadoop clusters have garnered attention. Connectors between Hadoop and fast MPP database clusters are not going away, but there is growing interest in moving many interactive SQL tasks into systems that coexist on the same cluster with Hadoop.
Having a Hadoop cluster support fast/interactive SQL queries dates back a few years to HadoopDB, an open source project out of Yale. The creators of HadoopDB have since started a commercial software company (Hadapt) to build a system that unites Hadoop/MapReduce and SQL. In Hadapt, a (Postgres) database is placed in nodes of a Hadoop cluster, resulting in a system2 that can use MapReduce, SQL, and search (Solr). Now on version 2.0, Hadapt is a fault-tolerant system that comes with analytic functions (HDK) that one can use via SQL. Read more…
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