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

Ying Zhang Y.Zhang at cwi.nl
Fri Mar 28 10:41:31 CET 2008


Hi Maurice,

Stupid me.  I only described how the current XRPC implementation is,  
but forgot to mention the ongoing work.

On Mar 28, 2008, at 09:35 , Keulen, M. van (Maurice) wrote:
> Hi Peter,
>
> Does it also mean that if I send a stream of messages to one server  
> that all carry the same request-ID without waiting for a result of a  
> message before sending out the next, that all are handled in the  
> correct order and each is handled after completion of the previous  
> one? In that case, it meets all my requirements. In fact, it gives  
> much more than I ask for :-) I definitely like to follow any  
> developments for this one!

This can be easily supported by adding a sequence number to each  
request message, I think.

But, if you have an updating request, and then a read-only request, do  
you then want to make the updates made by the first request visible to  
the second request?


Jennie


> Maurice.
>
> Peter Boncz wrote:
>> Hi,
>>
>> 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.
>>
>> Peter
>>
>>
>>
>>
>>> 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
>>>
>> *********************************
>>
>>
>
> -- 
> ----------------------------------------------------------------------
> 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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