Re: Database

[<aah@nofs.navy.mil>]

Paul,
  Thanks for your clarification.  While it is true that
you don't need to update for every star, and can use
a batch transaction, I see two problems:  the ~18 daily
updates will be posted at different times depending on
the site; and the database has to be available to the
outside sometime during the day!  So you cannot take it
off-line for extensive periods while updating.  So in
this sense, the database is 'real-time'.  You might
be able to ping-pong and have two versions running, one
that accepts outside queries and is updated once/day from
the other, which is doing the data entry.
  Archiving needs to be done periodically.  We had a few
cases where transactions needed to be backed out; this
is sometimes easier if you just restore the previous day's
master files.
  I haven't discussed the quality control issues:  removing
bad data, determining extinction/transformation coefficients
for each site or night, etc.
  What I am getting at is that, as with all large survey
efforts like MACHO or SDSS, data flow, archiving, quality
control and access are all difficult without personnel.
We don't have postdocs or FTEs, so all effort is voluntary.
The easier you make that effort, the more likely the
process is to succeed.  Otherwise, the more likely it is
that systems will not be run or else the sites will process
and keep their own data.  These are all obvious points,
but I just want people to keep them in mind.
Arne