107 research outputs found
Data Mining the SDSS SkyServer Database
An earlier paper (Szalay et. al. "Designing and Mining MultiTerabyte
Astronomy Archives: The Sloan Digital Sky Survey," ACM SIGMOD 2000) described
the Sloan Digital Sky Survey's (SDSS) data management needs by defining twenty
database queries and twelve data visualization tasks that a good data
management system should support. We built a database and interfaces to support
both the query load and also a website for ad-hoc access. This paper reports on
the database design, describes the data loading pipeline, and reports on the
query implementation and performance. The queries typically translated to a
single SQL statement. Most queries run in less than 20 seconds, allowing
scientists to interactively explore the database. This paper is an in-depth
tour of those queries. Readers should first have studied the companion overview
paper Szalay et. al. "The SDSS SkyServer, Public Access to the Sloan Digital
Sky Server Data" ACM SIGMOND 2002.Comment: 40 pages, Original source is at
http://research.microsoft.com/~gray/Papers/MSR_TR_O2_01_20_queries.do
The SDSS SkyServer, Public Access to the Sloan Digital Sky Server Data
The SkyServer provides Internet access to the public Sloan Digital Sky Survey
(SDSS) data for both astronomers and for science education. This paper
describes the SkyServer goals and architecture. It also describes our
experience operating the SkyServer on the Internet. The SDSS data is public and
well-documented so it makes a good test platform for research on database
algorithms and performance.Comment: submitted for publication, original at
http://research.microsoft.com/scripts/pubs/view.asp?TR_ID=MSR-TR-2001-10
AKARI-CAS --- Online Service for AKARI All-Sky Catalogues
The AKARI All-Sky Catalogues are an important infrared astronomical database
for next-generation astronomy that take over the IRAS catalog. We have
developed an online service, AKARI Catalogue Archive Server (AKARI-CAS), for
astronomers. The service includes useful and attractive search tools and visual
tools.
One of the new features of AKARI-CAS is cached SIMBAD/NED entries, which can
match AKARI catalogs with other catalogs stored in SIMBAD or NED. To allow
advanced queries to the databases, direct input of SQL is also supported. In
those queries, fast dynamic cross-identification between registered catalogs is
a remarkable feature. In addition, multiwavelength quick-look images are
displayed in the visualization tools, which will increase the value of the
service.
In the construction of our service, we considered a wide variety of
astronomers' requirements. As a result of our discussion, we concluded that
supporting users' SQL submissions is the best solution for the requirements.
Therefore, we implemented an RDBMS layer so that it covered important
facilities including the whole processing of tables. We found that PostgreSQL
is the best open-source RDBMS products for such purpose, and we wrote codes for
both simple and advanced searches into the SQL stored functions. To implement
such stored functions for fast radial search and cross-identification with
minimum cost, we applied a simple technique that is not based on dividing
celestial sphere such as HTM or HEALPix. In contrast, the Web application layer
became compact, and was written in simple procedural PHP codes. In total, our
system realizes cost-effective maintenance and enhancements.Comment: Yamauchi, C. et al. 2011, PASP..123..852
The Sloan Digital Sky Survey Science Archive: Migrating a Multi-Terabyte Astronomical Archive from Object to Relational DBMS
The Sloan Digital Sky Survey Science Archive is the first in a series of
multi-Terabyte digital archives in Astronomy and other data-intensive sciences.
To facilitate data mining in the SDSS archive, we adapted a commercial database
engine and built specialized tools on top of it. Originally we chose an
object-oriented database management system due to its data organization
capabilities, platform independence, query performance and conceptual fit to
the data. However, after using the object database for the first couple of
years of the project, it soon began to fall short in terms of its query support
and data mining performance. This was as much due to the inability of the
database vendor to respond our demands for features and bug fixes as it was due
to their failure to keep up with the rapid improvements in hardware
performance, particularly faster RAID disk systems. In the end, we were forced
to abandon the object database and migrate our data to a relational database.
We describe below the technical issues that we faced with the object database
and how and why we migrated to relational technology
SkyDOT (Sky Database for Objects in the Time Domain): A Virtual Observatory for Variability Studies at LANL
The mining of Virtual Observatories (VOs) is becoming a powerful new method
for discovery in astronomy. Here we report on the development of SkyDOT (Sky
Database for Objects in the Time domain), a new Virtual Observatory, which is
dedicated to the study of sky variability. The site will confederate a number
of massive variability surveys and enable exploration of the time domain in
astronomy. We discuss the architecture of the database and the functionality of
the user interface. An important aspect of SkyDOT is that it is continuously
updated in near real time so that users can access new observations in a timely
manner. The site will also utilize high level machine learning tools that will
allow sophisticated mining of the archive. Another key feature is the real time
data stream provided by RAPTOR (RAPid Telescopes for Optical Response), a new
sky monitoring experiment under construction at Los Alamos National Laboratory
(LANL).Comment: to appear in SPIE proceedings vol. 4846, 11 pages, 5 figure
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