Astronomical Data Query Language
The Astronomical Data Query Language (ADQL
) is the language used by the IVOA to represent astronomy queries posted to VO services. ADQL
is based on the Structured Query Language, especially SQL 92; special restrictions and extensions have been defined in order to support generic and astronomy specific operations.
The current IVOA Recommendation is ADQL-2.0
(30 October 2008).
page collects proposed features and notes while developing the next revision of the specification. ADQL-2_0-Errata
keeps track of the Errata status for this specific version of the recommendation.
ADQL-2.1 Working draft
The DAL group are working on developing the next version (2.1) of the ADQL
The latest version of the specification is available as a PDF document.
The source code for the document can be found online in the volute
The following command can be used to checkout a local copy of the document source.
svn checkout https://volute.g-vo.org/viewvc/volute/trunk/projects/dal/ADQL
BNF grammar validation effort
At the October 2016 interop in Trieste
the DAL group decided to delay putting the ADQL 2.1 working draft forward for the next stage of review
because there were questions about the validity of the Backus–Naur form
(BNF) definition of the language grammar included in the specification.
Prior to this, the BNF definition of the language grammar has been treated as a human readable resource that was interpreted manually by people developing ADQL
The October 2016 decision added a new requirement that the BNF definition of the language grammar needed to be machine readable and had to be validated against a set of standard queries.
In order to accomplish this, the Lyonetia GitHub project
has been set up to develop the tools and test data needed to create a machine readable version of the grammar.
To follow and contribute to this work please refer to the project plan