I am forwarding to qserv list...



On 04/05/2016 02:32 PM, Srinivasan Chandrasekharan wrote:
> Hi Jacek,
>
> I couldn’t think of anyone else to pose this DB problem to except you so
> here it is. Requesting your input:
>
> So I have a catalog of 600 million stars. The data that I have is :
>
> ra, dec, muRa, muDec, …. some mag columns etc etc.
>
> I want to add a few columns,
>
> 1. Add column for each row that tells me how many stars I have in the
> neighborhood with distance x.
> 2. Add column for each row that tells me how many stars I have in the
> neighborhood with distance x + 1.
>
> and so on ….
>
> The distances are of course in arcmin values. I guess the units dont
> quite matter and I do know that if I use spatial indexes this problem
> can be solved in SQL itself.
>
> I saw an old trac page
>
> https://dev.lsstcorp.org/trac/wiki/dbSpatialSupport
>
> Is there anything new that you know off that I could use? As you can see
> the DB is 600 million rows so about 100GB of data in a single table so I
> have to be slightly careful of what I execute.
>
> Just thought I would ask your opinion .. Just in case I am missing
> something..
>
> Regards,
>
> Srinivasan Chandrasekharan
> Senior Software Engineer,
> Large Synoptic Survey Telescope,
> Tucson, AZ 85726
> Phone: (520) 318-8383
> Fax : (520) 318-8424
> Email : [log in to unmask] <mailto:[log in to unmask]>
>

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