Introducing… Tez: Accelerating processing of data stored in HDFS

 

MapReduce has served us well.  For years it has been THE processing engine for Hadoop and has been the backbone upon which a huge amount of value has been created.  While it is here to stay, new paradigms are also needed in order to enable Hadoop to serve an even greater number of usage patterns.  A key and emerging example is the need for interactive query, which today is challenged by the batch-oriented nature of MapReduce.  A key step to enabling this new world was Apache YARN and today the community proposes the next step… Tez

What is Tez?

Tez – Hindi for “speed” – (currently under incubation vote within Apache) provides a general-purpose, highly customizable framework that creates simplifies data-processing tasks across both small scale (low-latency) and large-scale (high throughput) workloads in Hadoop. It generalizes the MapReduce paradigm to a more powerful framework by providing the ability to execute a complex DAG (directed acyclic graph) of tasks for a single job so that projects in the Apache Hadoop ecosystem such as Apache Hive, Apache Pig and Cascading can meet requirements for human-interactive response times and extreme throughput at petabyte scale (clearly MapReduce has been a key driver in achieving this).

With the emergence of Apache Hadoop YARN as the basis of next generation data-processing architectures, there is a strong need for an application which can execute a complex DAG of tasks which can then be shared by Apache Pig, Apache Hive, Cascading and others.  The constrained DAG expressible in MapReduce (one set of maps followed by one set of reduces) often results in multiple MapReduce jobs which harm latency for short queries (overhead of launching multiple jobs) and throughput for large-scale queries (too much overhead for materializing intermediate job outputs to the filesystem). With Tez, we introduce a more expressive DAG of tasks, within a single application or job, that is better aligned with the required processing task – thus, for e.g., any given SQL query can be expressed as a single job using Tez.

The below graphic illustrates the advantages provided by Tez for complex SQL queries in Apache Hive or complex Apache Pig scripts.

pighivetez

Tez is critical to the Stinger Initiative and goes a long way in helping Hive support both interactive queries and batch queries. Tez provides a single underlying framework to support both latency and throughput sensitive applications, there-by obviating the need for multiple frameworks and systems to be installed, maintained and supported, a key advantage to enterprises looking to rationalize their data architectures. .

Essentially, Tez is the logical next step for Apache Hadoop after Apache Hadoop YARN. With YARN the community generalized Hadoop MapReduce to provide a general-purpose resource management framework (YARN) where-in MapReduce became merely one of the applications that could process data in your Hadoop cluster. With Tez, we build on YARN and our experience with the MapReduce to provide a more general data-processing application to the benefit of the entire ecosystem i.e. Apache Hive, Apache Pig etc.

What has been completed? Where can Tez go?

An early version of the project has been donated to the ASF as part of the initial code grant to establish the Incubation project.   Through the work done in the Stinger initiative, it is already clear that Tez enables and order of magnitude increase in the performance of Apache Hive.

The community is also designing a re-usable set of libraries of data-processing primitives such as sorting, merging, data-shuffling, intermediate data management etc. which are necessary for Tez and may be used directly by other projects.  This is just the beginning.  It is an extensible architecture that will undoubtedly be contributed to widely.

For the community, by the community

At Hortonworks we believe that innovation happens fastest by working with a community of like-minded individuals to address the requirements for Hadoop without being bounded by artificial boundaries such as employment. As such, even though the Hortonworks MapReduce/Hive/Pig team seeded the project, we’ve had the benefit of both positive feedback and constructive criticism from several leading contributors and committers across the Apache Hadoop MapReduce, Apache Hive & Apache Pig projects.  These inventors and peers are employed at Hortonworks, Yahoo, Facebook, Microsoft, Twitter and many others.  The initial committer list has 22 participants with deep domain expertise in these unique challenges and comprises a who’s who in the Hadoop world.  Of course, now that we are nearly in a position where we can co-develop via the Apache Software Foundation where we have proposed Tez as an Incubator project, we expect a very quick acceleration of project development.

When will it be available?

We plan to donate the code from our internal repository to the ASF as part of the Incubator proposal.  Also, Hortonworks will ship Tez in the next alpha release of Hortonworks Data Platform 2 (HDP2), based on Apache Hadoop 2.0, very soon to showcase some of the very exciting advances we have made for Apache Hive via Project Stinger.

We are very excited by the reception Tez has received so far, and we do hope you can join us in this initiative via the Apache Software Foundation project to make Hadoop better!

Categorized by :
Apache Hadoop HDFS Hive MapReduce Other Tez YARN

Comments

Joe
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March 13, 2013 at 3:54 am
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Thanks for the write up, Arun. Given that Tez uses DAG model for processing workflows, how is it different than Oozie? Is it fair to consider Tez “Oozie on steroids”, or will the set of functionalities in Tez diverge entirely?

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February 20, 2013 at 4:06 pm
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IIRC – the vast majority of compute time in Hive workloads is spent in the first (typically large) stage. Once a great deal of reduction has happened – second stages are typically minor affairs.

Can you comment on why, in that case, for the project focused on latency – the focus is on how checkpointing across stages is done?

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