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Date: Mon, 10 Feb 2014 18:09:34 +0100
From: "Dag H. Wanvik" <dag.wanvik@oracle.com>
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To: derby-dev@db.apache.org
Subject: Re: Apache Derby - Query Validation
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On 10. feb. 2014 17:35, Madushanka Fonseka wrote:
> Hi,
>
> I have been working with Apache Derby for last few months (for a 
> research) and I need to know more about following mechanisms.My 
> research is based on innovating Derby to support fuzzy-logy based queries
>
>  (Ex. select * from student where /Avg/ is /good, /select * from 
> employee where /salary /is /low/)
>
> *1. How Qualifiers being created for different predicates ?*

Start looking at the WHERE clause code, e.g. in SelectNode.java, later 
pushed in ProjectRestrictNodes (in SelectNode#preprocess)

> *2. How a query or so as to speak something like "Salary > 55000" 
> being validated     against a row collection ?*

The evaluation of predicates are done in generated code, cf. the code in 
ProjectRestrictNode.java. Some predicates are
pushed down to the storage layer in the form of Qualifiers, cf. where 
PRN#modifyAccessPath calls pushUsefulPredicates.
The machinery is quite complex, so using an IDE/debugger will help 
understand what's happening.

> *3. How heap + conglomerate machinery get connected with this 
> Qualifie*rs *?*

Cf above.

Hope this helps,

Dag

>
> I would be pleased if you can give me some insight related to above 
> questions.
>
> *And on a different note I'd like to submit a research paper in regard 
> to my concept. I'd also like to know what would be the process for that.*
>
> Thanks,
>
> Madushanka Fonseka
> Computer Science Dept,
> Faculty of Engineering
> University of Moratuwa
> Sri Lanka
>
>
>
>
>
>


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    <div class="moz-cite-prefix">On 10. feb. 2014 17:35, Madushanka
      Fonseka wrote:<br>
    </div>
    <blockquote
cite="mid:CAPgZ1SJnRgXHA_UrpCeXsu3N6zSPwm+qMwYPf=gQ92bpaQX7WA@mail.gmail.com"
      type="cite">
      <div dir="ltr">Hi,
        <div><br>
        </div>
        <div>I have been working with Apache Derby for last few months
          (for a research) and I need to know more about following
          mechanisms.My research is based on innovating Derby to support
          fuzzy-logy based queries</div>
        <div><br>
        </div>
        <div>&nbsp;(Ex. select * from student where <i>Avg</i> is <i>good,&nbsp;</i>select
          * from employee where&nbsp;<i>salary&nbsp;</i>is&nbsp;<i>low</i>)</div>
        <div><br>
        </div>
        <div><b>1. How Qualifiers being created for different predicates
            ?</b></div>
      </div>
    </blockquote>
    <br>
    Start looking at the WHERE clause code, e.g. in SelectNode.java,
    later pushed in ProjectRestrictNodes (in SelectNode#preprocess)<br>
    <br>
    <blockquote
cite="mid:CAPgZ1SJnRgXHA_UrpCeXsu3N6zSPwm+qMwYPf=gQ92bpaQX7WA@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div><b>2. How a query or so as to speak something like "Salary
            &gt; 55000" being validated &nbsp; &nbsp; against a row collection ?</b></div>
      </div>
    </blockquote>
    <br>
    The evaluation of predicates are done in generated code, cf. the
    code in ProjectRestrictNode.java. Some predicates are<br>
    pushed down to the storage layer in the form of Qualifiers, cf.
    where PRN#modifyAccessPath calls pushUsefulPredicates.<br>
    The machinery is quite complex, so using an IDE/debugger will help
    understand what's happening.<br>
    <br>
    <blockquote
cite="mid:CAPgZ1SJnRgXHA_UrpCeXsu3N6zSPwm+qMwYPf=gQ92bpaQX7WA@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div><b>3. How heap + conglomerate machinery get connected with
            this Qualifie</b>rs <b>?</b></div>
      </div>
    </blockquote>
    <br>
    Cf above.<br>
    <br>
    Hope this helps,<br>
    <br>
    Dag<br>
    <br>
    <blockquote
cite="mid:CAPgZ1SJnRgXHA_UrpCeXsu3N6zSPwm+qMwYPf=gQ92bpaQX7WA@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div><br>
        </div>
        <div>I would be pleased if you can give me some insight related
          to above questions.</div>
        <div><br>
        </div>
        <div><b>And on a different note I'd like to submit a research
            paper in regard to my concept. I'd also like to know what
            would be the process for that.</b></div>
        <div><br>
        </div>
        <div>Thanks,</div>
        <div><br>
        </div>
        <div>Madushanka Fonseka</div>
        <div>Computer Science Dept,</div>
        <div>Faculty of Engineering</div>
        <div>University of Moratuwa</div>
        <div>Sri Lanka</div>
        <div><br>
        </div>
        <div><br>
        </div>
        <div><br>
        </div>
        <div><br>
        </div>
        <div><br>
        </div>
        <div><br>
        </div>
      </div>
    </blockquote>
    <br>
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