On Wed, Oct 14, 2015 at 9:13 PM, Emmanuel Lécharny <[email protected]> wrote:
> Hi guys, > > so we have clear case where the JDBM backend get corrupted, up to a > point a full reimport of the data is required. Lucas also proved that a > test will fail, after haing injected 1000 entries and doing 100 rename > (https://issues.apache.org/jira/browse/DIRSERVER-1974). > > This is more than annoying... > > I have tested DIRSERVER-1974 with Mavibot, and I can't reproduce the > problem, which means the server is safe. The resulting database is 14 Mb > big with the 1000 entries being added, which is big, but acceptable. > > At this point, I wonder if it would not be a safe approach to switch to > Mavibot right now ? > > The pros : > - we know that we can't have a database corruption, because each update > is a new revision > - technically, mavibot is faster than JDBM > - we aren't maintaining JDBM, while Mavibot is under development > > The cons : > - Mavibot is still under developement : we still have to add teh > cross-btree transactions, which means that if we have a brutal crash > during an update, then we may have some inconsistancy in the base > (inconsitancy != corruption, but still) > - We will still need the global write locking strategy to protect the > backend from concurrent reads and write when a update is processed > - The database is growing fast due to the limited cleanup we currently do > > However, in the middle term, Mavibot will bring the following bonuses : > - cross btree transaction support (actually, we may even support > multiple updates within a single transaction, speeding up the update > even more), which will allow us to remove the global RW lock we > currently have > - bulkloading capacity, increasing teh speed of injecting data by at > leats 2 orders of magnitude (server being stopped) > > > So, I'll ask you : what about releasing M21 with Mavibot as a default, > but with a possibility for users to still pick JDBM on demand ? > > I am in favor of that, I have tested it with the server few months ago after adding free page reclaiming functionality and it was _working_ The addition of entries gets slower after a point of time, but other than that I have not seen any other issues, this is just from one user pov though. Server needs to modify a bit to detect the type of storage used in an existing partition and initialize accordingly. -- Kiran Ayyagari http://keydap.com
