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Re: Always run dpkg --dry-run -i before running dpkg -i!

On Sat, Jan 08, 2005 at 01:20:02AM -0600, Peter Samuelson wrote:
> So, you're about 1/4 right.  Or, being charitable, if you really meant
> "*only* the Consistency part of ACID" when you said "ACID consistency",
> then you were right but quite misleading.

I know what it means, you're being pedagogical.
For the purposes of this discussion, it fits.

The domain of discourse is dependencies.
Assuming no packages are broken (i.e., our Transaction Monitor

Atomic: All of the dependencies are installed or none of them are.
Consistent: The system is transformed from one correct state to
another correct state.
Isolated: Other installations will not be broken by this
Durable: Dpkg is already durable.

You probably aren't aware of my extensions of how I work with
apt repositories which allows me to "commit" or "roll back"
transactions.  If an apt-operation succeed I move the files
to a new "known good" repository.  If it fails I perform
a balancing apt operation on using the old state.

Actually apt is like a Serializable transaction:  All locks
are acquired before any locks are released, in the sense
that it's guaranteed to succeed if it starts, assuming
individual packages themselves aren't broken.

Plus you're just being pedantic.  It's not exactly like
a database it's just a metaphor.  Whatever it is is what it is.

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