[V4RB] more questions

[Pedro fp]

Thanks to all for your advices so far. Ruslan you were correct when you 
suggested I'd have to completely re-engineer my application. I wish now 
that I'd started with Valentina months ago.

On Thursday, January 30, 2003, at 04:21  AM, Ruslan Zasukhin wrote:

>> Can the MaxLength of VString &/or VVarChar fields be changed at 
>> runtime?
>
> Yes, you can change practically any parameter in Valentina at runtime.
> But you need understand, that if you change length of field for table 
> with
> many records, this will take time.

I would not imagine Maxlength being changed regularly but because I'm 
also unsure of what kind of field to use I think a description of the 
situation is in order.

The application is a database for gene sequence data. Essentially it 
stores sequences plus a whole lot of meta-data about those sequences. 
Sequences are unbroken strings of letters [peptides] & highly variable 
in length. For one lab that's testing the software 300 peptides is 
exceptionally long, for some labs the average length is 24 000 
peptides. One of the meta-data fields is always [with L as the length 
of the sequence] 2 * L - 1 long. What I want to do is provide a user 
preference for the maximum length of sequences in their lab. If the 
user makes a good choice to begin with then it should never be changed 
once the database is populated.

I'm also considering adding a check on the length of new sequences 
that, if a new sequence is longer than MaxLength, would offer to adjust 
MaxLength for the user.

Although I have started work with the sequence as a VVarChar I am 
considering changing it to a VText because most sequences in most labs 
would be longer than 1024 peptides. This would also have the advantage 
of eliminating the whole question of MaxLength. I'm open to advice.

>> Is the page size of VVarChar fields always a multiple of 1024 bytes?
>
> Internally ? Yes.
>
> But this not affect you in fact.

I was thinking of taking advantage of the fact to set MaxLength to the 
maximum that would fit within a given page size.

Another question ...

The V4RB docs say the the IsMethod property is read only. So how do I 
set IsMethod to true? By making the SetMethod() call?

Cheers, Pedro :-)

Web: <http://www.pedro.net.au>                    PGP Key ID: 387CD96F
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