Re: [Firebird-devel] non-transportable backup using without "-seservice_mgr" results in an backup file ~50% larger than the source database

[Alex P. <pes...@ma...>]

 On 11/19/10 12:02, Dmitry Yemanov wrote:
> Alex,
>
>> The question is - are there any requirements in our API to what is
>> placed in the message buffer as a data for varchar field with zero
>> length? Should it be NULLs or may it be garbage?
> I believe garbage is acceptable, not only for zero-length strings but 
> also for NULLs (as we have an indicator stored separately). Although I 
> remember a hack we have regarding blobs: NULL blob must have zero blob 
> id, otherwise some applications started to work unpredictably, so we may 
> be sure that some applications ignore our API rules :-)
>
> But nothing prevents us from choosing the way which is better in 
> practice. You know that any record buffer is initially zapped with 
> zeroes to allow better compression later. So we may do the same for the 
> message buffers, unless it's proven to be too much expensive (as the 
> message processing is mostly CPU bound).
>
Taking into an account that some other application may also ignore
length, I will first try with zeroes initializing message buffers in
remote and see how does it affect performance. gbak's backup appears to
be very good test for it.