[mythtv-users] Is this DB schema as ambiguous as it looks?

[f-myth-users@media.mit.edu]

    > Date: Sun, 12 Feb 2006 18:41:19 -0500
    > From: Robert Tsai <rtsai1111 at comcast.net>

    > On Sun, Feb 12, 2006 at 06:20:54PM -0500, f-myth-users at media.mit.edu wrote:
    > > Tables like recordedmarkup seem to identify recordings by a tuple of
    > > (chanid, starttime), but that seems ambiguous---if you've got more
    > > than one tuner, it's perfectly possible to start a recording at time
    > > T on channel C as a normal recording, -and- to manually schedule a
    > > recording that -also- starts at time T on channel C that goes for a
    > > different length of time.  [See PS for why.]

    > If you "DESC CHANNEL" in MySQL, you will see that chanid must be
    > unique (it is the primary key).

    > And you can't have two recordings start at the same time for the same
    > chanid; there should be a conflict. That should ensure that starttime
    > is unique for a given chanid.

Well, you say that, but it just isn't true.  As a test, I scheduled
two simultaneous recordings for ch2, starting at 2200.  One was for
an hour (I just picked the program itself) and one was a manual
recording, for 5 minutes.  -Both- started; the 5-minute one stopped
after 5 minutes, and the 1-hour one is still recording.  My recordings
directory currently has two files:

  1002_20060212220000_20060212230000.nuv
  1002_20060212220000_20060212220500.nuv

The latter has stopped growing; the former is still growing.

    > > So now we've got two completely different files but only one way to
    > > refer to them in any table (like recordedmarkup) which doesn't also
    > > use the end time to disambiguate.  Is this likely to fatally confuse
    > > seeking or commflagging?  Might other things break?

    > The two recordings on the same chanid should have different starttime
    > values.

But---they don't, because they're both the same channel and they both
started at the same moment, exactly as I instructed Myth to do.

[This is in 18.  Does 19 enforce this in some way?]