Does CREATing a DB OPEN it?

> SHOW SESSIONS

> http://docs.basex.org/wiki/Commands#CREATE_DB

On Thu, Jul 26, 2012 at 3:53 PM, Godmar Back <godmar at gmail.com> wrote: > > ps: your current design, combined with your locking, also contains an > inherent race condition users cannot avoid. > > Namely, the statements > > CREATE DB dbname > CLOSE > > are not atomic. > > As such, if a 'CREATE DB' request for the same dbname arrives in a > different session before the created database was closed by the first > session, that request will fail with the error I've been getting - and > there's no way to avoid that in your design. You'd need a CREATE DB dbname > BUT DON"T OPEN IT command to avoid it. > > Just something to consider... > > - Godmar > > > _______________________________________________ > BaseX-Talk mailing list > BaseX-Talk at mailman.uni-konstanz.de > https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk > >

Am 26.07.2012 um 16:15 schrieb Michael Seiferle: > Hi Godmar, > Am 26.07.2012 um 15:47 schrieb Godmar Back: > >> Ok - you want your users to guess what weird design decisions you made, and document them. Unusual request. > thank you for your feedback. > http://docs.basex.org/wiki/Commands#CREATE_DB >> Creates the database [name] with an optional [input] and opens it. > Sorry this is not clearly stated on the Server’s documentation page, as Christian said writing documentation is a lot of work, feel free to improve when you feel something is missing. > > Thanks. :-) > > Michael

On Thu, Jul 26, 2012 at 4:49 PM, Godmar Back <godmar at gmail.com> wrote: > > I really don't understand your standoffishness, guys. > > I'm an open source contributor: debugging, testing, commenting. Read > Raymond's Bazaar. Some contributors play different roles, depending on the > project. I have projects I lead, projects where I code, and in some projects > I'm a debugger, tester, and commentator. That's the case with BaseX. You > should appreciate that. > > I'm just glad I eventually figured out what was causing the 'currently > opened' errors that led to intermittent (namely, if the request occurred in > a different session/connection) failures. > > - Godmar > > > On Thu, Jul 26, 2012 at 10:16 AM, Dirk Kirsten <dk at basex.org> wrote: >> >> Hello Godmar, >> >> While I in principle agree with your criticism about the side effects at >> the CREATE DB command and I also understand your frustration with a somehow >> unexpected behaviour, I'd like to remind you that BaseX is an open-source >> project. If Christian invites you to help to improve the documentation we do >> not imply that BaseX has to be fixed by its customers. However, as an >> open-source project we, of course, rely on the contribution of the community >> and we happily invite everyone to contribute to this project. So in this >> special case it could be one way to improve the documentation, but of course >> you are also invited to fix the issue and send a pull request on github. If >> you can't do this (e.g. because of time restrictions), that is also fine >> with us. Of course we will always try to fix issues - But we can just do >> this, if we are aware of them. As you just recently reported this issue, we >> now know about this issue and try to improve BaseX as a product - but of >> course you as a community member are also very welcome to help to improve >> it. >> >> Cheers, >> Dirk >> >> On Thu, Jul 26, 2012 at 3:53 PM, Godmar Back <godmar at gmail.com> wrote: >>> >>> >>> ps: your current design, combined with your locking, also contains an >>> inherent race condition users cannot avoid. >>> >>> Namely, the statements >>> >>> CREATE DB dbname >>> CLOSE >>> >>> are not atomic. >>> >>> As such, if a 'CREATE DB' request for the same dbname arrives in a >>> different session before the created database was closed by the first >>> session, that request will fail with the error I've been getting - and >>> there's no way to avoid that in your design. You'd need a CREATE DB dbname >>> BUT DON"T OPEN IT command to avoid it. >>> >>> Just something to consider... >>> >>> - Godmar >>> >>> >>> _______________________________________________ >>> BaseX-Talk mailing list >>> BaseX-Talk at mailman.uni-konstanz.de >>> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk >>> >> >

> > http://docs.basex.org/wiki/Commands#CREATE_DB > > I have added a hint on that in the documentation. Apart from this > page, there are several others indicating that a created database will > automatically be opened; e.g.: > > http://docs.basex.org/wiki/Standalone_Mode > http://docs.basex.org/wiki/Database_Server > >

> CREATE DB <http://docs.basex.org/wiki/Commands#CREATE_DATABASE> xmark

> OPEN <http://docs.basex.org/wiki/Commands#OPEN> xmark

> XQUERY <http://docs.basex.org/wiki/Commands#XQUERY> //people/person/name

If you feel that the documentation is insufficient, it's easy to > contribute! You are invited to get an account. > >

On Thu, Jul 26, 2012 at 10:16 AM, Dirk Kirsten <dk at basex.org> wrote: > Hello Godmar, > > While I in principle agree with your criticism about the side effects at > the CREATE DB command and I also understand your frustration with a somehow > unexpected behaviour, I'd like to remind you that BaseX is an open-source > project. If Christian invites you to help to improve the documentation we > do not imply that BaseX has to be fixed by its customers. However, as an > open-source project we, of course, rely on the contribution of the > community and we happily invite everyone to contribute to this project. So > in this special case it could be one way to improve the documentation, but > of course you are also invited to fix the issue and send a pull request on > github. If you can't do this (e.g. because of time restrictions), that is > also fine with us. Of course we will always try to fix issues - But we can > just do this, if we are aware of them. As you just recently reported this > issue, we now know about this issue and try to improve BaseX as a product - > but of course you as a community member are also very welcome to help to > improve it. > > Cheers, > Dirk > > On Thu, Jul 26, 2012 at 3:53 PM, Godmar Back <godmar at gmail.com> wrote: > >> >> ps: your current design, combined with your locking, also contains an >> inherent race condition users cannot avoid. >> >> Namely, the statements >> >> CREATE DB dbname >> CLOSE >> >> are not atomic. >> >> As such, if a 'CREATE DB' request for the same dbname arrives in a >> different session before the created database was closed by the first >> session, that request will fail with the error I've been getting - and >> there's no way to avoid that in your design. You'd need a CREATE DB dbname >> BUT DON"T OPEN IT command to avoid it. >> >> Just something to consider... >> >> - Godmar >> >> >> _______________________________________________ >> BaseX-Talk mailing list >> BaseX-Talk at mailman.uni-konstanz.de >> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk >> >> >