Re: [Firebird-devel] Firebird and DSQL Scrollable Cursors

[Mark R. <ma...@la...>]

On 26-11-2021 10:10, Dmitry Yemanov wrote:
> Mark et al,
> 
>> Yes, I think that is perfectly acceptable for an initial version. 
>> Scrollable cursors are a bit of an oddity anyway, but having 
>> scrollable cursors in embedded access, but not in remote access is 
>> IMHO less acceptable than bad performance. As long as the performance 
>> behaviour is clearly documented, people can make the decision if the 
>> bad performance is worth the utility of scrollable cursors for 
>> themselves.
> 
> I've just committed network support for scrollable cursors to master. 
> Prefetch logic is supported for NEXT/PRIOR navigations. Protocol changes 
> are documented here:
> 
> https://github.com/FirebirdSQL/firebird/issues/7051
> 
> The test set to cover different navigation scenarios is being created, 
> once it's ready we'll validate the results between PSQL cursors, 
> embedded access, network access w/prefetch and network access 
> wo/prefetch (FOR UPDATE added to SELECTs). Obviously, we expect them to 
> match ;-)
> 
> I'd appreciate if Mark could test scrollability from the Jaybird side 
> too (i.e. without fbclient involved), but the new protocol should be 
> supported for that.

I will have to implement scrollability (Jaybird currently emulates it by 
materializing the entire result set in memory) before I can test it.

> The committed version is linked to protocol 17 which was introduced for 
> 4.0.1. Thus technically, this improvement can be backported and released 
> together with v4.0.1. However, I'm not sure this risk is acceptable for 
> a point release and I'm ready to introduce protocol 18 in master for v5. 
> Opinions, please.

Personally, I think this is better to surface in Firebird 5, than rush 
it into Firebird 4.0.1.

Mark
-- 
Mark Rotteveel