Re: [Monotone-devel] [RFC] Monotone NETSYNC Hook Extension & Abstraction Layer

[Thomas Keller]

Markus Schiltknecht schrieb:
> Thomas Keller wrote:
>>> http://www.sqlite.org/cvstrac/wiki?p=UndoRedo might be a good
>>> starting point.
>>
>> Doesn't this violate the ACID properties of a normal transaction
> 
> Uh huh? The above link describes a temporary table "holding the
> information needed to undo/redo changes to the database". That certainly
> does not pose any problems regarding ACID properties.

If a revision, which is added to a monotone database, is recorded as
several single inserts and/or other operations which itself run inside a
transaction, you can't say for sure that a decomposition of this single
transaction into several SQL commands, which are then recorded and
applied backwards without any transaction mechanism will never somehow
introduce database inconsistencies.

Sure, this may not be a problem at all if the database you're applying
the redo on is not used by a second process, but Zack proposed this for
Ralf's NETSYNC use case AFAIR.

Thomas.

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