Re: [Firebird-devel] Collection of garbage in record with uncommitted version

[Vlad K. <hv...@us...>]

>   If a record has uncommitted head version created by active transaction and some garbage 
> in backversions "tail", can anyone (background GC thread, sweep or parallel transaction) 
> wipe this garbage from the tail while the transaction is still active?

    Yes

>   I can't understand why list_staying() is so picky: it scans for every next version from 
> the beginning which raise its complexity to O(N^2).

    list_staying used to undo dead record version. It is not a most often operation. And, yes, 
it is terrible inefficient. It restarts from the beginning of the versions chain when need next 
record version because :
a) it used handoff's to make sure backpointers is valid
b) data page with target version is released 

Regards,
Vlad