Concurrent Transaction control in MonetDB

Vijay Krishna vijayakrishna55 at gmail.com
Mon Oct 19 08:26:55 CEST 2015


Thanks for the clarifications.

If so, then there is a minor probability that if 2 concurrent requests are
trying to update a column in a row, then even a genuine latest request
would simply be ignored and the data will be having the older request only.

Am I getting this right?




Thanks & Regards,

Vijayakrishna.P.
Mobile : (+91) 9500402305.

On Sun, Oct 18, 2015 at 2:24 PM, Sjoerd Mullender <sjoerd at monetdb.org>
wrote:

> The first transaction that actually attempts to commit wins.  You can't
> wait for the last concurrent transaction, because it might not commit at
> all and then nobody can commit.  This would also be a recipe for a
> denial of service attack.
> Reasons it might not commit are, it does a rollback, it is a badly
> written application that never terminates, or either the application or
> the server crashes.
>
> On 10/18/2015 08:01 AM, Vijay Krishna wrote:
> > Hi,
> >
> > I read the following lines in a thesis on MonetDB titled - "Improving
> > Transactional Stability in MonetDB" where in they had explained the
> > concurrency control in MonetDB as
> >
> > "Concurrent updates (writers) are not anticipated and in case of N
> > con􏰃icting transactions, only one of them (the one having the earliest
> > time-stamp) is guaranteed to eventually commit its changes.
> > Concurrent appends (on the same table) are detected as write-to-write
> > conflicts and only the writer carrying the earliest time-stamp will end
> > up committing successfully, the rest will be aborted."
> >
> > Why is that the transaction having the earliest timestamp is allowed to
> > commit, in case of a conflict?
> > Shouldn't it be the latest transaction that should commit on a data,
> > since the latest transaction would be having the latest version of data?
> >
> > Or, what am I getting wrong here? Any help much appreciated.
> >
> >
> > Thanks & Regards,
> >
> > Vijayakrishna.P.
> > Mobile : (+91) 9500402305.
> >
> >
> > _______________________________________________
> > developers-list mailing list
> > developers-list at monetdb.org
> > https://www.monetdb.org/mailman/listinfo/developers-list
> >
>
> --
> Sjoerd Mullender
>
>
> _______________________________________________
> developers-list mailing list
> developers-list at monetdb.org
> https://www.monetdb.org/mailman/listinfo/developers-list
>
>
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