Removing the global transaction from ldbmodify (was Re: [SCM] Samba Shared Repository - branch master updated - release-4-0-0alpha6-90-g3942e53)

[Andrew Bartlett]

On Fri, 2009-01-23 at 14:18 -0500, simo wrote:
> On Fri, 2009-01-23 at 19:44 +0100, Stefan (metze) Metzmacher wrote:
> > Hi Simo,
> > 
> > >     Do not start a transaction this way.
> > >     Because we still want to commit any changes that successfully apply we
> > >     never want to do a global cancel, and because of how transaction nesting
> > >     works that means we never cancel any "transaction" at the single modify
> > >     operation level.
> > 
> > Who says that? I think it's quite useful to only apply all operations!

Indeed!

> > We should at least have a command line option to control this.
> > And also have all ldb tools in sync with this behavior.
> > 
> > Could you please revert that for now.
> 
> Nope, the previous behavior leaves the database in an inconsistent state
> if an operation that should modify multiple entries based on a
> triggering modify fails.
> The reason is that if a module returns an error the transaction is not
> canceled. (Tested with a module I am writing)

Then this is what should be fixed!

> The intended behavior of ldbmodify was to apply all mods that could be
> successfully applied, but it did not do that correctly.
> My change fixes a real problem.
> 
> If you want to modify the intended behavior I am ok, but the code right
> now works correctly. Reverting will make it wrong.
> 
> >  Then we could readd this to all
> > tools with an option. Where I don't care what default behavior we choose.
> 
> Unless my change is causing problems I think a revert would be worng,
> you can still add an option to have a real global transaction without
> any revert.

We should add an option to apply the partial set, but given that we have
transactions, we really should use them globally by default - and the
admin would expect that they be on the global/whole file level.

The other issue here is that this was added as a speedup - I understand
from tridge that the global transaction is faster, because of the single
'write & sync'.

Andrew Bartlett

-- 
Andrew Bartlett
http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org
Samba Developer, Red Hat Inc.
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