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From Bertrand Delacretaz <>
Subject Re: [RESULT][VOTE] Accept MRQL into the Incubator
Date Mon, 18 Mar 2013 10:31:15 GMT
On Sun, Mar 17, 2013 at 4:01 PM, Mohammad Nour El-Din
<> wrote:
> On Sun, Mar 17, 2013 at 11:49 AM, Alex Karasulu <>wrote:
>> We're also missing Ant Elder from the Nominated Mentors list no?
> Fixed...

I have pasted the current version of the proposal below, so that this
list has it correctly archived.

+1 to incubation based on that version with four mentors.




MRQL is a query processing and optimization system for large-scale,
distributed data analysis, built on top of Apache Hadoop and Hama.


MRQL (pronounced miracle) is a query processing and optimization
system for large-scale, distributed data analysis. MRQL (the MapReduce
Query Language) is an SQL-like query language for large-scale data
analysis on a cluster of computers. The MRQL query processing system
can evaluate MRQL queries in two modes: in MapReduce mode on top of
Apache Hadoop or in Bulk Synchronous Parallel (BSP) mode on top of
Apache Hama. The MRQL query language is powerful enough to express
most common data analysis tasks over many forms of raw in-situ data,
such as XML and JSON documents, binary files, and CSV documents. MRQL
is more powerful than other current high-level MapReduce languages,
such as Hive and PigLatin, since it can operate on more complex data
and supports more powerful query constructs, thus eliminating the need
for using explicit MapReduce code. With MRQL, users will be able to
express complex data analysis tasks, such as PageRank, k-means
clustering, matrix factorization, etc, using SQL-like queries
exclusively, while the MRQL query processing system will be able to
compile these queries to efficient Java code.


The initial code was developed at the University of Texas of Arlington
(UTA) by a research team, led by Leonidas Fegaras. The software was
first released in May 2011. The original goal of this project was to
build a query processing system that translates SQL-like data analysis
queries to efficient workflows of MapReduce jobs. A design goal was to
use HDFS as the physical storage layer, without any indexing, data
partitioning, or data normalization, and to use Hadoop (without
extensions) as the run-time engine. The motivation behind this work
was to build a platform to test new ideas on query processing and
optimization techniques applicable to the MapReduce framework.

A year ago, MRQL was extended to run on Hama. The motivation for this
extension was that Hadoop MapReduce jobs were required to read their
input and write their output on HDFS. This simplifies reliability and
fault tolerance but it imposes a high overhead to complex MapReduce
workflows and graph algorithms, such as PageRank, which require
repetitive jobs. In addition, Hadoop does not preserve data in memory
across consecutive MapReduce jobs. This restriction requires to read
data at every step, even when the data is constant. BSP, on the other
hand, does not suffer from this restriction, and, under certain
circumstances, allows complex repetitive algorithms to run entirely in
the collective memory of a cluster. Thus, the goal was to be able to
run the same MRQL queries in both modes, MapReduce and BSP, without
modifying the queries: If there are enough resources available, and
low latency and speed are more important than resilience, queries may
run in BSP mode; otherwise, the same queries may run in MapReduce
mode. BSP evaluation was found to be a good choice when fault
tolerance is not critical, data (both input and intermediate) can fit
in the cluster memory, and data processing requires complex/repetitive

The research results of this ongoing work have already been published
in conferences (WebDB'11, EDBT'12, and DataCloud'12) and the authors
have already received positive feedback from researchers in academia
and industry who were attending these conferences.


MRQL will be the first general-purpose, SQL-like query language for
data analysis based on BSP.
Currently, many programmers prefer to code their MapReduce
applications in a higher-level query language, rather than an
algorithmic language. For instance, Pig is used for 60% of Yahoo!
MapReduce jobs, while Hive is used for 90% of Facebook MapReduce jobs.
This, we believe, will also be the trend for BSP applications,
because, even though, in principle, the BSP model is very simple to
understand, it is hard to develop, optimize, and maintain non-trivial
BSP applications coded in a general-purpose programming language.
Currently, there is no widely acceptable declarative BSP query
language, although there are a few special-purpose BSP systems for
graph analysis, such as Google Pregel and Apache Giraph, for machine
learning, such as BSML, and for scientific data analysis.
MRQL can capture many complex data analysis algorithms in declarative form.
Existing MapReduce query languages, such as HiveQL and PigLatin,
provide a limited syntax for operating on data collections, in the
form of relational joins and group-bys. Because of these limitations,
these languages enable users to plug-in custom MapReduce scripts into
their queries for those jobs that cannot be declaratively coded in
their query language. This nullifies the benefits of using a declarative
query language and may result to suboptimal, error-prone, and
hard-to-maintain code. More importantly, these languages are
inappropriate for complex scientific applications and graph analysis,
because they do not directly support iteration or recursion in
declarative form and are not able to handle complex, nested scientific
data, which are often semi-structured. Furthermore, current MapReduce
query processors apply traditional query optimization techniques that
may be suboptimal in a MapReduce or BSP environment.
The MRQL design is modular, with pluggable distributed processing
back-ends, query languages, and data formats.
MRQL aims to be both powerful and adaptable. Although Hadoop is
currently the most popular framework for large-scale data analysis,
there are a few alternatives that are currently shaping form,
including frameworks based on BSP (eg, Giraph, Pregel, Hama), MPI (eg,
OpenMPI), etc. MRQL was designed in such a way so that it will be easy
to support other distributed processing frameworks in the future. As
an evidence of this claim, the MRQL processor required only 2K extra
lines of Java code to support BSP evaluation.
Initial Goals

Some current goals include:

apply MRQL to graph analysis problems, such as k-means clustering and PageRank
apply MRQL to large-scale scientific analysis (develop general
optimization techniques that can apply to matrix multiplication,
matrix factorization, etc)
process additional data formats, such as Avro, and column-based
stores, such as HBase
map MRQL to additional distributed processing frameworks, such as
Spark and OpenMPI
extend the front-end to process more query languages, such as standard
SQL, SPARQL, XQuery, and PigLatin
Current Status

The current MRQL release (version 0.8.10) is a beta release. It is
built on top of Hadoop and Hama (no extensions are needed). It
currently works on Hadoop up to 1.0.4 (but not on Yarn yet) and Hama
0.5.0. It has only been tested on a small cluster of 20 nodes (80


The initial MRQL code base was developed by Leonidas Fegaras in May
2011, and was continuously improved throughout the years. We will
reach out other potential contributors through open forums. We plan to
do everything possible to encourage an environment that supports a
meritocracy, where contributors will extend their privileges based on
their contribution. MRQL's modular design will facilitate the
strategic extensions to various modules, such as adding a standard-SQL
interface, introducing new optimization techniques, etc.


The interest in open-source query processing systems for analyzing
large datasets has been steadily increased in the last few years.
Related Apache projects have already attracted a very large community
from both academia and industry. We expect that MRQL will also
establish an active community. Several researchers from both academia
and industry who are interested in using our code have already
contacted us.

Core Developers

The initial core developer was Leonidas Fegaras, who wrote the
majority of the code. He is an associate professor at UTA, with
interests in cloud computing, databases, web technologies, and
functional programming. He has an extensive knowledge and working
experience in building complex query processing systems for databases,
and compilers for functional and algorithmic programming languages.


MRQL is built on top of two Apache projects: Hadoop and Hama. We have
plans to incorporate other products from the Hadoop ecosystem, such as
Avro and HBase. MRQL can serve as a testbed for fine-tuning and
evaluating the performance of the Apache Hama system. Finally, the
MRQL query language and processor can be used by Apache Drill as a
pluggable query language.

Known Risks

Orphaned Products

The initial committer is from academia, which may be a risk, since
research in academia is publication-driven, rather than
product-driven. It happens very often in academic research, when a
project becomes outdated and doesn't produce publishable results, to
be abandoned in favor of new cutting-edge projects. We do not believe
that this will be the case for MRQL for the years to come, because it
can be adapted to support new query languages, new optimization
techniques, and new distributed back-ends, thus sustaining enough
research interest. Another risk is that, when graduate students who
write code graduate, they may leave their work undocumented and
unfinished. We will strive to gain enough momentum to recruit
additional committers from industry in order to eliminate these risks.

Inexperience with Open Source

The initial developer has been involved with various projects whose
source code has been released under open source license, but he has no
prior experience on contributing to open-source projects. With the
guidance from other more experienced committers and participants, we
expect that the meritocracy rules will have a positive influence on
this project.

Homogeneous Developers

The initial committer comes from academia. However, given the interest
we have seen in the project, we expect the diversity to improve in the
near future.

Reliance on Salaried Developers

Currently, the MRQL code was developed on the committer's volunteer
time. In the future, UTA graduate students who will do some of the
coding may be supported by UTA and funding agencies, such as NSF.

Relationships with Other Apache Products

MRQL has some overlapping functionality with Hive and Tajo, which are
Data Warehouse systems for Hadoop, and with Drill, which is an
interactive data analysis system that can process nested data. MRQL
has a more powerful data model, in which any form of nested data, such
as XML and JSON, can be defined as a user-defined datatype. More
importantly, complex data analysis tasks, such as PageRank, k-means
clustering, and matrix multiplication and factorization, can be
expressed as short SQL-like queries, while the MRQL system is able to
evaluate these queries efficiently. Furthermore, the MRQL system can
run these queries in BSP mode, in addition to MapReduce mode, thus
achieving low latency and speed, which are also Drill's goals.
Nevertheless, we will welcome and encourage any help from these
projects and we will be eager to make contributions to these projects

An Excessive Fascination with the Apache Brand

The Apache brand is likely to help us find contributors and reach out
to the open-source community. Nevertheless, since MRQL depends on
Apache projects (Hadoop and Hama), it makes sense to have our software
available as part of this ecosystem.


Information about MRQL can be found at MRQL: an Optimization Framework
for Map-Reduce Queries

Initial Source

The initial MRQL code has been released as part of a research project
developed at the University of Texas at Arlington under the Apache 2.0
license for the past two years. The source code is currently hosted on
GitHub at: MRQL’s release artifact
would consist of a single tarball of packaging and test code.

External Dependencies

The MRQL source code is already licensed under the Apache License,
Version 2.0. MRQL uses JLine which is distributed under the BSD


Not applicable.

Required Resources

Mailing Lists

Subversion Directory

Git is the preferred source control system: git://
Issue Tracking

A JIRA issue tracker, MRQL

Moinmoin wiki,
Initial Committers

Leonidas Fegaras <fegaras AT cse DOT uta DOT edu>
Upa Gupta <upa.gupta AT mavs DOT uta DOT edu>
Edward J. Yoon <edwardyoon AT apache DOT org>
Maqsood Alam <maqsoodalam AT hotmail DOT com>
John Hope <john.hope AT oracle DOT com>
Mark Wall <mark.wall AT oracle DOT com>
Kuassi Mensah <kuassi.mensah AT oracle DOT com>
Ambreesh Khanna <ambreesh.khanna AT oracle DOT com>
Karthik Kambatla <kasha AT cloudera DOT com>

Leonidas Fegaras (University of Texas at Arlington)
Upa Gupta (University of Texas at Arlington)
Edward J. Yoon (Oracle corp)
Maqsood Alam (Oracle corp)
John Hope (Oracle corp)
Mark Wall (Oracle corp)
Kuassi Mensah (Oracle corp)
Ambreesh Khanna (Oracle corp)
Karthik Kambatla (Cloudera)


Alex Karasulu <akarasulu AT apache DOT org>
Nominated Mentors

Anthony Elder <antelder AT apache DOT org>
Alex Karasulu <akarasulu AT apache DOT org>
Mohammad Nour <mnour AT apache DOT org>
Alan Cabrera <adc AT apache DOT org>

Sponsoring Entity

Incubator PMC

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