[V4WS] question on deleting records

[Ruslan Zasukhin]

on 3/15/03 2:01 AM, Luca Porfiri at liste at mail.sting.it wrote:

> Hi Ruslan and everyone,
> 
> I am searching for hints on deleting records from a very big BaseObject with
> a very big index.
> Let me describe how big:
> 
> the db is
> .blb = 1,57 Gb
> .dat = 425 Mb
> .ind = 253 Mb
> 
> the main BaseObject has 230.000 record and the amount of index depends on
> this BaseObject.
> Every day I update the db and index with 4Mb of data ca.
> The index is big enough to contain, at now, 98% of words contained in the
> new records I go to add to db and WS + Valentina update is very fast at
> least.
> I use this procedure:
> 
> read all the file to import
> split it by record using \r to know number of records
> then i repeat for every record:
>  make a cursor with all fields I will populate
>  select with itemAt the record in the list of records I want to process
>  split it in fields (using tab in the text of record as separator)
>  then valSetBlankRecord
>  then valAddRecord and valSetField fields with values of the fields in
> record to add
>  finally valUpdateRecord
> and back again to the next record and so on ...
> It's fast enough to add and update also the indexes ... could we do better?
> 
> NOW
> 
> I need to delete old records but I fear it because delete records means
> update also indexes and this operation, I believe, is not so fast as adding
> records (but why?) I believe, instead, it could be very very slow ... or
> not?
> So could it be a way to do this fast?

Delete must be as fast as Add.

It is update() command take = time of delete + time of Add.
So it should be in average 2 times slower.

> Is better to select little cursors and deleteAll or delete record by record
> or other?

Well, DeleteAll should be faster in theory.

If you have so big db of important data, I hope you do backups.
So after backup you can try DeleteAll for single cursor.

You need this operation only once?

-- 
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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