big table V4RB 1.10, RB 5.52, OS X 10.3

[Ruslan Zasukhin]

On 6/5/04 10:49 AM, "olivier vidal" <vidal_olivier at yahoo.fr> wrote:

>> Because Valentina store each filed into separate logical file.
>> So the more columns the more files, the more disk writes.
>> 
>> When you make cursor with 5 fields on table with 150 fields,
>> Such cursor will work in 30 times faster of cursor with all fields.
>> 
>> 
> Thus, if I use a table with 150 fields, to be effective, it would be
> necessary never to use " SELECT * ", but to try to select still only
> the necessary fields?

Yes of course!
 
This is general rule for ANY DBMS.
For Valentina this is even more important.


> - A cursor of 10 fields will thus work much more quickly in reading
> that a cursor of 60 fields because there will be 6 times less of
> logical files to be read.

yes

> But if I write the value of a SINGLE field. My cursor has 10 or 60
> fields, the writing will be made only on 1 logical file?

It seems yes. 
You talk here about UPDATE, yes?

Add Record of course must write into each 60.


> If 1 single logical file ( 1 single field) is modified, why the writing
> would set more time with a cursor of 60 fields than with a cursor of 10
> fields?

Right. Must be the same.

Faster will be iteration of such cursor, Next()/Prev()


-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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