Sorry for the confusion. I was trying to draw an analogy -- not a one-to-one correspondence -- suggesting that not every single attribute will be necessary for every single astronomer browse-type query. For example, lots of shape parameters for extended objects may be permissable to exclude when "browsing" the catalog (if there is some compelling database efficiency or cost savings to be gained -- if not, then I agree with Kem that we give them everything).
- Kirk ----- Original Message ----- From: Kem Cook <[EMAIL PROTECTED]> Date: Wednesday, July 5, 2006 8:01 pm Subject: Re: [LSST-data] [Fwd: Re: [lsst-slac] Cone-magnitude-color search] > Hi, > > I think one of us is confused. I am presuming we are talking about > reduced data in the object table, while the example Kirk gives is > for an > HST Science observation which is more-or-less the equivalent of > our Image > table. I agree there will be lots of metadata associated with > each Image > which most scientists won't find useful, but I think scientists > will want > most/all of the attributes of 'objects' which are returned from a > search. > cheers, > > Kem > > > For different reasons, but with same effect, the HST ARchive > > group (where I worked 11 years ago) decided to use VIEWs. > > Eventhough the VIEW will not be materialized (in the LSST DB), > > it does limit the number of attributes selected with "SELECT *" > > catch-all queries. For HST, we developed a SCIENCE table > > view, which included only the most likely interesting > > attributes for scientists. It was still a significant > > number of attributes, but much less than the underlying > > database tables that fed into it. Maybe we could try something > > similar for LSST, since maybe not every astronomer who > > issues a "SELECT *" query really wants E-V-E-R-Y-T-H-I-N-G. > > > > To see which attributes the HST SCIENCE table provides, look here: > > > > http://archdev.stsci.edu:8080/hst/manual/datadesc.htm#962859 > > > > Another subset of attributes is available in the HST AEC = Archived > > Exposures Catalog, which I invented 16 years ago, and it is still > > generated and in use today.... (amazing!) .... > > > > http://archdev.stsci.edu:8080/hst/aec.html > > > > The AEC has been quite valuable for a number of organizations > > who want to maintain their own small-ish local version of the HST > > science catalog for their own local queries and analyses. > > > > Therefore, I think Kem's comment can still be correct, > > but for a smaller number of attributes. However, what I don't > > know is whether the above limitations in the number of attributes > > help Jacek's situation. > > > > - Kirk > > > > > >> From [EMAIL PROTECTED] Wed Jul 5 18:09:00 2006 > >> Date: Wed, 05 Jul 2006 15:05:48 -0700 > >> From: Jacek Becla <[EMAIL PROTECTED]> > >> Subject: [LSST-data] [Fwd: Re: [lsst-slac] Cone-magnitude-color > search]>> To: LSST Data Management <[email protected]> > >> > >> Keywords: DataAccWG > >> > >> Sorry, sent to the wrong mailing list the first time... > >> > >> Jacek > >> > >> > >> > >> -------- Original Message -------- > >> Subject: Re: [lsst-slac] Cone-magnitude-color search > >> Date: Wed, 5 Jul 2006 14:18:48 -0700 (PDT) > >> From: Kem Cook <[EMAIL PROTECTED]> > >> Reply-To: lsst-llnl-slac collab <[EMAIL PROTECTED]> > >> To: lsst-llnl-slac collab <[EMAIL PROTECTED]> > >> CC: lsst-llnl-slac collab <[EMAIL PROTECTED]> > >> References: <[EMAIL PROTECTED]> > >> > >> Most school kids would want time, mag, magerr, colors, > colorserrs for > >> each > >> objID returned. Professional astronomers would probably want > >> everything. > >> > >> Kem > >> > >> > Keywords: DataAccWG > >> > > >> > Hi Kem and Kirk, > >> > > >> > Now that I started to assume we have memory for caching indexes, > >> > I need to know whether selecting everything from Object table > >> > for the "Cone-magnitude-color search" > >> > > >> > SELECT * > >> > FROM Object > >> > WHERE ra BETWEEN <Ra1> AND <Ra2> > >> > AND decl BETWEEN <Decl1> AND <Decl2> > >> > AND zMag BETWEEN <z1> AND <z2> > >> > AND gMag-rMag BETWEEN <gr1> AND <gr2> > >> > AND iMag-zMag BETWEEN <iz1> AND <iz2> > >> > > >> > is realistic. The reason I am asking is that if user wanted > >> > objectId, ra, dec, plus all colors plus all magnitudes instead > >> > of "everything", we could do this query without fetching > >> > data rows. The "select *" in this query alone is driving number > >> > of disks up by 23% (assuming 300 low volume queries per > >> > 10 high volume...). > >> > > >> > thanks, > >> > Jacek > >> > _______________________________________________ > >> > lsst-slac mailing list > >> > [EMAIL PROTECTED] > >> > http://www.lsstmail.org/mailman/listinfo/lsst-slac > >> > > >> > >> _______________________________________________ > >> lsst-slac mailing list > >> [EMAIL PROTECTED] > >> http://www.lsstmail.org/mailman/listinfo/lsst-slac > >> _______________________________________________ > >> LSST-data mailing list > >> [email protected] > >> http://www.lsstmail.org/mailman/listinfo/lsst-data > >> > > > > _______________________________________________ > > LSST-data mailing list > > [email protected] > > http://www.lsstmail.org/mailman/listinfo/lsst-data > > > > _______________________________________________ LSST-data mailing list [email protected] http://www.lsstmail.org/mailman/listinfo/lsst-data
