Re: Re: ZopeUndo.Prefix is still used

On Sun, Aug 14, 2016, at 18:37, Jim Fulton wrote:
> On Sun, Aug 14, 2016 at 9:04 AM, Hanno Schlichting
> <[email protected]> wrote:
>> Undo management in Zope2 is now available in its ZMI control panel on
>>  each configured database object, instead of contextually on ZMI
>>  folders.
>
> I'm not sure I understand this.  FWIW, if we need the ability to
> filter undoLog/undoInfo at some point, I'd be happy to discuss some
> sort of specification language based on data structures that don't
> require instances.

Sure, that makes sense for ZODB in general.

From my experience with Zope2/CMF based projects, they all just tend
to use the ZCatalog and most of them tend to index some kind of
modification time. As a result almost all transactions actually end
up changing not just a content object somewhere, but also the exact
same BTree bucket inside the ZCatalog and this bucket sees constant
bucket splits.

As a result it almost never works to selectively undo some transactions,
but in this context it only works to undo all transactions from most
current back to a prior state, including all transactions in between.

That's what the ZMI on Zope2 master still allows, by simply showing
all transactions and allowing you to undo them in order for each
configured storage.

Hope that is a bit clearer,
Hanno

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