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From:Sinisa Milivojevic Date:June 7 2001 1:17pm
Subject:Re: General Question
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Sharifullah Khan wrote:

>>On 2001 Jun 06, Jani Tolonen <jani@stripped> wrote:
>>
>>>Sharifullah Khan writes:
>>> > I'm a PhD student, new to mySQL and also to this mailing list. I
> defined
>>> > some operators in relational algebra for Selection, Projection, and
>>>
>Join to
>
>>> > compute differential results form a relation. Now I want to implement
>>>
>these
>
>>> > operators in mySQL. I don't know where I start from. I will be very
>>>
>thank
>
>>> > full to one who put me on track.
>>>
>>>Ps. For the future, if you have general questions about MySQL,
>>>please post them to mysql@stripped.
>>>
>>Sharifullah, I think Jani misunderstood your question.  It seems that
>>you want to extend MySQL's syntax with selection, projection and join
>>operators.  If you can give us a brief description of how you would
>>like these operators to work in MySQL, we should be able to direct
>>you to the right parts of the code to be modified.
>>
>
>Tim,
>Yes, Jani could not understand me. I'm working on continual queries that
>are persistent. A query is evaluated on the whole data at first time. After
>initial evaluation, the query is interested only in updated data. We
>developed differential operators to evaluate the query only on updated data.
>
>We use a differential relation to store updated data of a relation. The
>operators are evaluated on the differential relation. However, only
>differential relations are not sufficient for Join, because it can need
>existing data.  
>
>Similar techniques are used for incremental recompuatation of materialised
>views in data warehousing.
>
>So, We need operators to extract updated data from a relation, to tag
>tuples of updated data differently for  insertion, deletion and
>modification; and to store it in differential relation continously. An
>operator to direct the query to differential relation after initial
>evaluation. The matter is complex for Join, because it needs both
>differential and base relations. At the last, we need operators to compute
>insertion, deletion, or complete result form the differential result of
>differenatial operators.
>
>This is a brief description of my Project.
>
>Regrads,
>Sharif
>
>
>Sharifullah Khan
>
>School of Computing;
>University of Leeds,
>Leeds LS2 9JT, UK
>
>Email:khan@stripped
>Tel#: 0113-233 6788
>Fax#: 0113-233 5468
>
>
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Hi!

You can achieve what you need with MySQL by using our TEMPORARY TABLES.

After running first query, create a temporary table out of it and after 
that make LEFT JOIN's with new snapshots over the previous ones.

-- 

Regards,

Sinisa

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Thread
General QuestionSharifullah Khan6 Jun
  • General QuestionJani Tolonen6 Jun
    • Re: General QuestionTimothy Smith6 Jun
      • Re: General QuestionSharifullah Khan7 Jun
    • Re: General QuestionSinisa Milivojevic7 Jun