RE: R-tree indexing, RA wrap and LISTENing

["Creager, Robert S" <CreagRS@LOUISVILLE.STORTEK.COM>]

> -----Original Message-----
> From: Doug Welch [mailto:welch@physics.mcmaster.ca] 
> Subject: R-tree indexing
> 
> Two questions:
> 
> 1) Is R-tree indexing being used on coordinate boxes of type 
> box? If not, this would be a superb idea since R-tree indexed 
> coordinate box queries (overlap, contained-within, etc) are 
> viciously efficient and PostgreSQL implements this index.

I'm using B-Tree indexes to manage my RA/Dec searches, and it works quite
well.  My query uses circle_contains_pt, but I've also bound the RA/DEC by
using BETWEEN.  I may have to take a look at this.  Maybe I can do away with
the BETWEEN.

Any thoughts on how to handle the stars that sit at 0 RA (or very close)?
I've been toying with creating a new PostgreSQL type which manages this wrap
automatically, but only got a very little way into that one.

> 
> 2) Is anyone considering implementing an "alert" query which 
> would be triggered by a object being added outside previous 
> object positions (if they exist for that part of the sky) 
> and/or not in the Tycho list? This would be a way of 
> detecting moving objects, flare stars, novae, etc.

PostgreSQL has NOTIFY/LISTEN, which is used for just this purpose.  A set of
NOTIFY events would be created, and folks could sign up to receive e-mail of
these events.  Then the LISTEN would query the dB to see who wanted
notification, and then send e-mail.

> 
> Cheers,
> Doug
> 

Later,
Rob