Issues with yum

[John Reiser]

On 02/27/2012 08:11 AM, Panu Matilainen wrote:

> Rpm's so-called transactions aren't ACID by any stretch of imagination, it's just a rather common misunderstanding to expect them to be.

OK, so both rpm and yum could do better: at the first mention of 'transaction',
then the documentation (manual page, ...) should specify "not ACID".
There is a database involved, and the word 'transaction' had a decade
of precedence in the database world before rpm was written.

Because rpm does not support ACID transactions, then yum should act
to minimize the adverse impact.  Do not process the packages in
alphabetical order; instead sort the packages topologically: the
ones with no remaining dependencies go first, etc.  Then responding
immediately to ^C [SIGINT] can leave at most one package in an
inconsistent state (assuming no circular dependencies.)
Or, it might be reasonable to finish processing that one package
before not starting the rest of the work.

Additionally, sorting each topological tier by descending size
tends to minimize the number of packages changed before any SIGINT,
so this is an inexpensive way give the interactive user more control.
However, sorting by ascending size tends to enable earlier detection
of systematic problems across packages.  On average for a DVD, sorting
by size (and processing in the same direction) is significantly better
than random by size because the linear caching of most drives (2MB typical)
becomes much more effective on average for adjacent small files
if not all are selected.

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