ADQL XMATCH
Alex Szalay
szalay at jhu.edu
Wed Feb 10 09:08:01 CET 2016
This is a paper we published 4 years ago about this. The service is now in beta testing.
We just bought 4 dedicated servers.
http://arxiv.org/pdf/1206.5021v1.pdf
--Alex
-----Original Message-----
From: dal-bounces at ivoa.net [mailto:dal-bounces at ivoa.net] On Behalf Of Markus Demleitner
Sent: Wednesday, February 10, 2016 1:54 AM
To: dal at ivoa.net
Subject: Re: ADQL XMATCH
Hi Alex,
On Tue, Feb 09, 2016 at 07:55:33PM +0000, Alex Szalay wrote:
> I agree with Tom, that this approach is completely flawed. The notion
> of a spatial crossmatch is not a logical value, but it is a posterior
> likelihood, or at best a Bayes factor which can (and
> should) be combined with additional attributes like shape, flux, color
> etc.
I always like it when something is based on a good theory, and sometimes a good theory explains why there appear to be no satisfying solutions to an existing problem[1].
So: based on a probabilistic analysis of crossmatching, do you have a proposal for how these concepts could be mapped into ADQL language elements?
Thanks,
Markus
[1] which here is: everyone wants to do crossmatches, and what ADQL right now offers is the highly unpopular (and also boolean)
1=CONTAINS(POINT('ICRS', ra, dec), CIRCLE('ICRS', basera, basedec))
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