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From Hyunsik Choi <>
Subject [VOTE] Accept Tajo into the Apache Incubator
Date Thu, 28 Feb 2013 18:11:30 GMT
Hi Folks,

I'd like to call a VOTE for acceptance of Tajo into the Apache incubator.
The vote will close on Mar 7 at 6:00 PM (PST).

[] +1 Accept Tajo into the Apache incubator
[] +0 Don't care.
[] -1 Don't accept Tajo into the incubator because...

Full proposal is pasted at the bottom on this email, and the corresponding
wiki is

Only VOTEs from Incubator PMC members are binding, but all are welcome to
express their thoughts.


PS: From the initial discussion, the main changes are that I've added 4 new
committers. Also, I've revised some description of Known Risks because the
initial committers have been diverse.

Tajo Proposal

= Abstract =

Tajo is a distributed data warehouse system for Hadoop.

= Proposal =

Tajo is a relational and distributed data warehouse system for Hadoop. Tajo
is designed for low-latency and scalable ad-hoc queries, online aggregation
and ETL on large-data sets by leveraging advanced database techniques. It
supports SQL standards. Tajo is inspired by Dryad, MapReduce, Dremel,
Scope, and parallel databases. Tajo uses HDFS as a primary storage layer,
and it has its own query engine which allows direct control of distributed
execution and data flow. As a result, Tajo has a variety of query
evaluation strategies and more optimization opportunities. In addition,
Tajo will have a native columnar execution and and its optimizer. Tajo will
be an alternative choice to Hive/Pig on the top of MapReduce.

= Background =

Big data analysis has gained much attention in the industrial. Open source
communities have proposed scalable and distributed solutions for ad-hoc
queries on big data. However, there is still room for improvement. Markets
need more faster and efficient solutions. Recently, some alternatives
(e.g., Cloudera's Impala and Amazon Redshift) have come out.

= Rationale =

There are a variety of open source distributed execution engines (e.g.,
hive, and pig) running on the top of MapReduce. They are limited by MR
framework. They cannot directly control distributed execution and data
flow, and they just use MR framework. So, they have limited query
evaluation strategies and optimization opportunities. It is hard for them
to be optimized for a certain type of data processing.

= Initial Goals =

The initial goal is to write more documents to describe Tajo's internal. It
will be helpful to recruit more committers and to build a solid community.
Then, we will make milestones for short/long term plans.

= Current Status =

Tajo is in the alpha stage. Users can execute usual SQL queries (e.g.,
selection, projection, group-by, join, union and sort) except for nested
queries. Tajo provides various row/column storage formats, such as CSV,
RowFile (a row-store file we have implemented), RCFile, and Trevni, and it
also has a rudimentary ETL feature to transform one data format to another
data format. In addition, Tajo provides hash and range repartitions. By
using both repartition methods, Tajo processes aggregation, join, and sort
queries over a number of cluster nodes. To evaluate the performance, we
have carried out benchmark test using TPC-H 1TB on 32 cluster nodes.

== Meritocracy ==

We will discuss the milestone and the future plan in an open forum. We plan
to encourage an environment that supports a meritocracy. The contributors
will have different privileges according to their contributions.

== Community ==

Big data analysis has gained attention from open source communities,
industrial and academic areas. Some projects related to Hadoop already have
very large and active communities. We expect that Tajo also will establish
an active community. Since Tajo already works for some features and is in
the alpha stage, it will attract a large community soon.

== Core Developers ==

Core developers are a diverse group of developers, many of which are very
experienced in open source and the Apache Hadoop ecosystem.

 * Eli Reisman <ereisman AT apache DOT org>

 * Henry Saputra <hsaputra AT apache DOT org>

 * Hyunsik Choi <hyunsik AT apache DOT org>

 * Jae Hwa Jung <jhjung AT gruter DOT com>

 * Jihoon Son <ghoonson AT gmail DOT com>

 * Jin Ho Kim <jhkim AT gruter DOT com>

 * Roshan Sumbaly <rsumbaly AT gmail DOT com>

 * Sangwook Kim <swkim AT inervit DOT com>

 * Yi A Liu <yi DOT a DOT liu AT intel DOT com>

== Alignment ==

Tajo employs Apache Hadoop Yarn as a resource management platform for large
clusters. It uses HDFS as a primary storage layer. It already supports
Hadoop-related data formats (RCFile, Trevni) and will support ORC file. In
addition, we have a plan to integrate Tajo with other products of Hadoop
ecosystem. Tajo's modules are well organized, and these modules can also be
used for other projects.

= Known Risks =

== Orphaned Products ==

Most of codes have been developed by only two core developers, who are
Hyunsik Choi and Jihoon Son. It may be a risk of being orphaned. However,
they are guaranteed to have enough time to develop Tajo for years. As you
can see the commit history, they have participated in this project for
about two years. In addition, the initial committers are diverse, and Tajo
has been supported by two IT companies in South Korea. So, the risk of
being orphaned is very low. Later, we will be eager to recruit additional
committers in order to eliminate this risk.

== Inexperience with Open Source ==

Most of the initial committers have experience working on open source
projects. In particular, Eli, Henry, and Hyunsik have experience as
committers and PMC members on other Apache projects.

== Homogeneous Developers ==

Although they are a diverse group of developers, what a half of core
developers are in South Korea may be a risk. This is because their offline
activities are limited due to their location. Since we surely recognize
this risk, we will write more complete documents and presentation materials
in order to disseminate Tajo's internal and users guide. In addition, to
mitigate this risk we will be eager to recruit additional committers around
the world.

== Reliance on Salaried Developers ==

It is expected that Tajo development will occur on both salaried time and
on volunteer time. Hyunsik and Jihoon belong to Database lab., Korea Univ.
They will be paid by the lab to contribute Tajo for years. Jin Ho and
Sangwook are paid by their employer to contribute to this project. Other
developers will contribute to this project on volunteer time. In addition,
we will be eager to recruit additional committers including salaried and
non-salaried developers.

== Relationships with Other Apache Products ==

Tajo has some overlapping function with Apache Incubator Drill. However,
Tajo is even more mature than Drill. In addition, there are some
significant differences. Drill is a distributed system specialized for
low-latency query processing by using column operations and intermediate
data streaming. Drill has very simple query optimizer. However, some
queries including big-big table join and sort are not available in that
manner. Drill will support some of query types.

In contrast, Tajo has advanced query optimization system. Tajo mainly aims
at scalable and efficient processing on all query types. By using the query
optimizer, Tajo will only chase low latency query processing for some query
types that can be executed in online aggregation manner.

Besides, Tez has some overlapping functions with Tajo. However, Tez is in
the pre-alpha stage and may be a prototype. When Tez becomes feasible, Tajo
could use Tez as an underlying framework according to the applicability.
However, Tajo will still use its row/native columnar execution engine and
its optimizer. Tajo may be potentially the first application of Tez.

== A Excessive Fascination with the Apache Brand ==

We believe that the Apache brand will help us to find contributors and to
grow the community. The community and development process will make this
project more stable and help establish ubiquitous APIs. In addition, Tajo
depends other project in Apache Hadoop ecosystem. We expect that
cooperative work occurs with other projects in the same place.

= Documentation =

Tajo's demonstration paper was accepted to IEEE ICDE 2013. Since this
conference will be held in April 2013, we cannot publicly show the paper.
Instead, we attached some presentation material. Checkout this slide (

In addition, some documents (e.g., getting started) are available at

= Initial Source =

The initial source code has been developed in the Database Lab. Korea Univ.
This is implemented in Java and has almost 100,000 lines except for parser
and protobuf generated codes. Currently, initial source code is already
available on GitHub at [[]].

= Source and Intellectual Property Submission Plan =

We intend the entire code base to be licensed under the Apache License,
Version 2.0.

= External Dependencies =

The required dependencies are all Apache compatible licenses. The following
components with non-Apache licenses are enumerated:

 * Google Guava

 * Google Protocol Buffer

 * Antlr

 * Mockito

 * JLine2

= Cryptography =

 Tajo will depend on secure Hadoop that can optionally use Kerberos.

= Required Resources =

== Mailling List ==

 * tajo-private (with moderated subscriptions)

 * tajo-dev

 * tajo-commits

== Subversion Directory ==

== Issue Tracking ==

Jira Tajo (TAJO)

== Other Resources ==

 * Continuous Integration

   * Jenkins

 * Wiki


= Initial Committers =

 * Eli Reisman <ereisman AT apache DOT org>

 * Henry Saputra <hsaputra AT apache DOT org>

 * Hyunsik Choi <hyunsik AT apache DOT org>

 * Jae Hwa Jung <jhjung AT gruter DOT com>

 * Jihoon Son <ghoonson AT gmail DOT com>

 * Jin Ho Kim <jhkim AT gruter DOT com>

 * Roshan Sumbaly <rsumbaly AT gmail DOT com>

 * Sangwook Kim <swkim AT inervit DOT com>

 * Yi A Liu <yi DOT a DOT liu AT intel DOT com>

= Affiliations =

 * Eli Reisman (Hortonworks)

 * Henry Saputra (Platfora)

 * Hyunsik Choi (Database Lab., Korea University)

 * Jae Hwa Jung (Gruter)

 * Jihoon Son (Database Lab., Korea University)

 * Jin Ho Kim (Gruter)

 * Roshan Sumbaly (LinkedIn)

 * Sangwook Kim (Inervit)

 * Yi A Liu (Intel)

The nominated mentors are employees of NASA JPL, LinkedIn, and Hortonworks.

 * Chris Mattmann - NASA JPL

 * Jakob Homan - LinkedIn

 * Owen O'Malley - Hortonworks

= Sponsors =

== Champion ==

 * Jakob Homan <ghoman AT apache DOT org>

== Nominated Mentors ==

 * Chris Mattmann <chris DOT a DOT mattmann AT jpl DOT nasa DOT gov>

 * Jakob Homan <jghoman AT apache DOT org>

 * Owen O'Malley <omalley AT apache DOT org>

== Sponsoring Entity ==

Apache Incubator

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