0 votes
10 views
asked May 28 by datalab (1,610 points) | 10 views

1 Answer

0 votes

ADQL (Astronomical Data Query Language; http://www.ivoa.net/documents/latest/ADQL.html) is based on SQL92 and defines a set of restrictions and extensions to support generic and astronomy specific operations. It is used extensively with TAP (Table Access Protocol; http://www.ivoa.net/documents/TAP/20100327). ADQL is implementation agnostic so SQL extensions specific to a particular RDBMS, such as the q3c spatial indexing for Postgres, are not valid within ADQL queries. Perhaps of most use are the geometric functions which ADQL defines and can be included in a query statement; for example,

select * from some.table where CONTAINS(POINT('J2000',ra,dec),CIRCLE('J2000',121.17,-21.57,1.0))=1

will find all objects which lie within a circle of radius 1 of the specified point (see http://tapvizier.u-strasbg.fr/adql/help.html for further examples).

answered May 31 by anonymous

59 questions

39 answers

0 comments

12 users

Welcome to Data Lab Help Desk, where you can ask questions and receive answers from other members of the community.