[ZODB-Dev] Re: [Zope-dev] Conflict reduced BTrees for catalogin

[Dieter Maurer]

Tim Peters wrote at 2003-3-13 23:01 -0500:
 > [Jeremy Hylton]
 > > Conflict resolution for BTrees is very subtle.  I'd like to see a
 > > careful analysis of what impact ignoring read conflicts will have.  It's
 > > definitely impossible for internal nodes, but it might be possible for
 > > buckets.
 > >
 > > Can you prove that ignoring read conflicts is safe?  If you can't, then
 > > I'd say it isn't worth the risk.

I know already one problem:

  Letting "_p_independent" return 1 allows to see state modified
  after the current transaction started.

  When I do this for catalog data but not other data,
  then searches can return objects that are not yet accessible.

I have abandoned the "_p_independent for BTrees" route and
will go for "ReadCommitted" isolation level.
This provides for much clearer semantics.

Thank you for your comment!
Dieter