[Monetdb-developers] Monetdb-developers Digest, Vol 22, Issue 4

Peter Boncz P.Boncz at cwi.nl
Thu Mar 27 19:13:07 CET 2008


I read the digests of the monetdb mailing list, which in this case took more
than a month to send me this discussion. That's pretty useless.. I will switch
to immediate mails.

Anyway, Jennie is currently working on getting the repeatable reads transactions
working. This means that by passing a request-ID you will be guaranteed that all
queries and updates execute on the same database image, i.e. a transaction. In
case of update requests in the same transaction, these will be executed
atomically using a 2PC protocol.
While this functionality is designed to be triggerered from XQuery queries, you
client API could also generate the appropriate messages.

It may not answer you needs regarding performance (you would send a
read-request, update-request, prepare-request and commit-request), but it would
answer your functional requirements AFAIS.


> Message: 1
> Date: Wed, 19 Mar 2008 12:30:20 +0100
> From: "Keulen, M. van (Maurice)" <m.vankeulen at utwente.nl>
> Subject: Re: [Monetdb-developers] [XQ] Mixing update/docmgmt/query
> To: monetdb-developers at lists.sourceforge.net
> Message-ID: <47E0F94C.4000709 at utwente.nl>
> Content-Type: text/plain; charset=windows-1252; format=flowed
> Ying Zhang wrote:
> >
> >> Jennie: my SOAP-messages do not come from MonetDB/XQuery, but from 
> >> outside (i.e., some scripting language).
> >
> > Then, an order can only be guaranteed if you, in your 
> scripts, send a 
> > message, wait for result, and send the next message.  In all other 
> > cases, unfortunately, no guarantee, as an xrpc server immediately 
> > start handling a request when it's received.
> >
> > Jennie
> I thought so already. This is why I don't like to have to 
> send multiple 
> requests to do one thing (transaction). I'd rather be able to 
> send one 
> request to both do, say, an update and return a result, or add a 
> document and return a result. The system so far doesn't allow 
> me to do 
> this, because I cannot define one query (or function in a 
> module) that 
> does both because of typing restrictions, and I also cannot send two 
> separate queries in one request because of restrictions in the XRPC 
> protocol.
> Any thoughts about achieving what I want?
> Maurice.
> -- 
> ----------------------------------------------------------------------
> Dr.Ir. M. van Keulen - Assistant Professor, Data Management Technology
> Univ. of Twente, Dept of EEMCS, POBox 217, 7500 AE Enschede, 
> Netherlands
> Email: m.vankeulen at utwente.nl, Phone: +31 534893688, Fax: +31 
> 534892927
> Room: ZI 3039, WWW: http://www.cs.utwente.nl/~keulen

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