11,664 research outputs found
Development of 2MASS Catalog Server Kit
We develop a software kit called "2MASS Catalog Server Kit" to easily
construct a high-performance database server for the 2MASS Point Source Catalog
(includes 470,992,970 objects) and several all-sky catalogs. Users can perform
fast radial search and rectangular search using provided stored functions in
SQL similar to SDSS SkyServer. Our software kit utilizes open-source RDBMS, and
therefore any astronomers and developers can install our kit on their personal
computers for research, observation, etc. Out kit is tuned for optimal
coordinate search performance. We implement an effective radial search using an
orthogonal coordinate system, which does not need any techniques that depend on
HTM or HEALpix. Applying the xyz coordinate system to the database index, we
can easily implement a system of fast radial search for relatively small (less
than several million rows) catalogs. To enable high-speed search of huge
catalogs on RDBMS, we apply three additional techniques: table partitioning,
composite expression index, and optimization in stored functions. As a result,
we obtain satisfactory performance of radial search for the 2MASS catalog. Our
system can also perform fast rectangular search. It is implemented using
techniques similar to those applied for radial search. Our way of
implementation enables a compact system and will give important hints for a
low-cost development of other huge catalog databases.Comment: 2011 PASP accepte
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
Staircase Join: Teach a Relational DBMS to Watch its (Axis) Steps
Relational query processors derive much of their effectiveness from the awareness of specific table properties like sort order, size, or absence of duplicate tuples. This text applies (and adapts) this successful principle to database-supported XML and XPath processing: the relational system is made tree aware, i.e., tree properties like subtree size, intersection of paths, inclusion or disjointness of subtrees are made explicit. We propose a local change to the database kernel, the staircase join, which encapsulates the necessary tree knowledge needed to improve XPath performance. Staircase join operates on an XML encoding which makes this knowledge available at the cost of simple integer operations (e.g., +, <=). We finally report on quite promising experiments with a staircase join enhanced main-memory database kernel
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