Sequential filtering in SQL

[Ruslan Zasukhin]

On 12/12/05 5:40 PM, "Ed Kleban" <Ed at Kleban.com> wrote:

>> Table Methods = Calculated fields is an answer.
>> You make some Method, setup its formula which return e.g. True/false
>> Do 
>> 
>>   set1 = fldMethod.FindValue( 1 )
>> 
>> Change method, and do next search.
> 
> Aha!  I think you are right :)  And it looks like a very good answer!
 
> So help me understand this a bit better.  Unfortunately other than
> mentioning that that calculated fields exist and noting how to define, them
> neither the Kernel nor the V4RB Reference provide any significant
> documentation describing calculated fields.

I think exists text which describe WHEN you get benefits from them.
Probably in Kernel.pdf

> When I define a calculated field in the API, and then perform a FindValue
> for example on that field, the interface is essentially taking my method and
> passing it over to the SQL engine somehow behind my back, getting an answer,
> and returning a VSet somehow?

No, SQL engine is not used here. Only parser to parse formula and get nodes.

Future when you use it million times, it looks like you work with already
compiled c++ code.
 
> Or does Valentina have a native expression analyzer that can interpret the
> MethodText, render it into code for the calulcated field, and uses it for
> Find commands without going through SQL?

yes
 
>> This will be not indexed searches.
> 
> Of course, I'm not expecting them to be.  I'm getting the speed from
> applying the searches sequentially and thus reducing the number of records
> that need to be searched each time.

-- 
Best regards,

Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc

Valentina - Joining Worlds of Information
http://www.paradigmasoft.com

[I feel the need: the need for speed]