Collaboration on Source Catalogue DM, ADQL and SkyNodes

[Mark Taylor]

On Wed, 21 Dec 2005, Jim Gray wrote:

> There is also the cross match that Tanu & Maria implemented in SQL.
> That may be the easiest way to do the implementation if the nodes all
> have a SQL backend. 
> When things are "in" the database it runs fast ~100k object/sec for
> small radius. 
> But, getting objects into a node dominates all other costs (moving stuff
> thru xml is expensive). 
> We recently found some logic errors in our "zones" cross match (near the
> meridian and poles) but seem to have a fix for them now. 
> Maria can tell you all about this (it is the subject of her PhD). 

Jim (and lurkers),

certainly the STIL/STILTS match is not going to compete with an SQL one
which makes use of precomputed indices; it's designed for the case where 
you've got data with no advance preparation (typically just an unsorted 
list of (RA,Dec,other-data) rows, for instance a FITS table or VOTable
streamed or on disk).  Since Pedro says he's interested in client-side 
matching, I presume that the data's not going to be in a database and 
in general no RDBMS will even be available for use.  However, it depends 
a bit on what is meant here by "client".

Mark

-- 
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/