Hi Kostsi, Well my query can have only one parameter - the size of the squares in the grid. Then I want the query just yield groups of points (1 group for 1 square in the grid). I don't even need to backtrack the points to the squares in the grid - I don't need a query "Give me all of points in this particular square" (but sure would be better for debugging). I just need to work with these groups of points separately. How to do this practically is another thing - maybe building some hierarchical index which will assign IDs to the squares in the grid will be necessary. An far more advanced example than I need could be https://code.google.com/p/q3c/ for relational DB. Cheers, JN
-----Original Message----- From: users-list [mailto:users-list- bounces+nadvornik.ji=gmail.com@monetdb.org] On Behalf Of Kostis Kyzirakos Sent: 16. března 2015 18:07 To: users-list@monetdb.org Subject: Re: Geometrical grid for spherical data
Hi Jiri, What kind of queries would you like to run on this data? Can you give me some examples?
Cheers, Kostsi
On 03/16/2015 06:04 PM, Jiří Nádvorník wrote:
Hi All,
I have spherical coordinates (right ascension, declination) and I’d like to iterate over areas in this 2-dimensional space. Easiest that comes to mind is just create a grid of squares (say 5 arcsecs wide) and iterate over them.
Is it easier to do this in MonetDB with just spherical coordinates (some kind of spherical index), or do I have to convert them to x,y,z coordinates and create the grid in 3D?
Thank you for your insight.
Jiri Nadvornik
Astronomical Institute AV CR
Stellar department
Czech Republic
nadvornik.ji@gmail.com <mailto:nadvornik.ji@gmail.com>
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