on 6/24/02 22:20, Marc Van Olmen at marc At tribeworks .D.OT com wrote:
Hi Marc,
>>> * to make your database fast keep the database file itself as small as
>>> possible. So it is better not to use BLOB and keep the files in an external
>>> folder.
>>
>> Totally wrong !!!
>>
>> Of course size of database affect general performance -- it is faster search
>> table with 1000 records than table with 10 millions of records.
>>
>> But! Valentina has smart storage of BLOBs, so they DO NOT affect in any way
>> speed of search for table.
> That'is not true what you are saying, indeed you can do all kind of
> optimisations techniques BUT most of the people do the following: they will
> query the database and then show a result list in a Table/List viewer now to
> display that data will go a lot faster if the database is small especialy
> when the database is on a CD/DVD where this person was refering too;
> In the many CD based database title I made we always had one big Table file
> containing all the data and then we build a seperated Table just containing
> the data that was being used to display the result list (for example: name
> of the company, city). This resulted in a 4x ... 10x times increase in
> displaying the list combined with smart caching techniques the results where
> even bigger.
You talk about different thing to original text (the first paragraph above).
1) In original text was told that IF store BLOBs in DB table, you get slow
speed. This is NOT true...at least for Valentina.
******
2) Marc, what you describe is related to problem of
effective displaying of selected records in view.
Even stronger -- when user can scroll forward and back many times.
Also you self touch here 2 aspects of this problem.
2.1) For example you have million of records in table,
user select 1000 records in query.
Most probably these records are spread in the big table.
So if user will scroll records database must JUMP on big table.
Of course better then copy this 1000 records into new small table.
But this works only if user really will MANY time scroll data.
2.2) Another thing you point -- that for this small table you have already
LESS number of fields.
Now good news. Cursors of Valentina do not touch not selected fields.
In other words, if you have in table 100 fields, but in query select only 5
fields, then cursor will read from disk ONLY these 5 fields.
I must note that other DBs need read all 100 fields to obtain that 5 for
you.
******
3) In future version, Valentina allow you choose if cursor must have own TMP
table, then Valentina will build this small TMP table for you automatically.
--
Best regards,
Ruslan Zasukhin
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e-mail: ruslan@paradigmasoft.com
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