On 09/21/2011 11:03 AM, Daniel Shahaf wrote: >> But before we press on here, I'd like to understanding your bigger-picture >> view. > > The branch operates on the assumption that an efficiently-queryable > successors store should be managed by the FS. In this thread I'm > further assuming that creating successors would be expensive and > therefore 'svnadmin upgrade' should create a 'miscellaneous' table > record and bump the format number. > > There is a concurrent thread by Stefan2 that challenges both of these > assumptions. I don't know that we have consensus yet whether the design > in that thread or the design currently on the branch are better. (And, > yes, figuring that is the second thing at the top of my list, next to > figuring out how to implement 'upgrade' on the branch.)
Yeah, I'm not following Stefan2's thread very closely. But regardless of
what he thinks Subversion *should* have, I don't know of any reasons why it
should *not* have this successor-id mapping.
>> Why are you choosing to this by-revision in fs_base rather than using
>> a more lower-level, largely-Subversion-ignorant approach? Is it
>> specifically so you can have an interruptible/restartable process? Is it so
>> you can hook into some pre-existing per-revision subsystem (notification,
>> perhaps)?
>
> I was simply trying to outline an algorithm for populating the
> successors store from scratch in a live FS. (And yes, both
> restartability and notification are nice properties to have.)
Okay. I'm not sure that I would take the same course in a live FS versus an
offline one, and you've been referring to 'upgrade' which shouldn't be run
on a live FS -- that is, it should make the FS effectively "not live" for
the duration of the upgrade. So, I'm a touch confused about what
specifically you are aiming at.
But here's the extent of my assumptions: you want to backfill successors as
quickly, efficiently, and painlessly as possible, ideally without
interrupting live operation of the repository. Is that fair? :-)
> It's not clear to me exactly what the alternatives your question refers
> to are. Could you elaborate on them, please?
Well, BDB being a real database, we can do this sort of backfill operation
without attending to any higher-level Subversion concepts such as revisions
at all. A cursor walk through the `nodes' table should suffice:
for key, value in nodes_table.rows()
successor_id = key
node_rev = parse_node_revision_skel(value)
successors_table.add_row(node_rev.predecessor_id, successor_id)
--
C. Michael Pilato <cmpil...@collab.net>
CollabNet <> www.collab.net <> Distributed Development On Demand
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