Re: [HACKERS] Review: GIN non-intrusive vacuum of posting tree

2017-03-22 22:48 GMT+05:00 Teodor Sigaev <teodor@sigaev.ru>:
> hasEmptyChild? and hasNonEmptyChild (BTW, isAnyNonempy has missed 't')

Yes, I think this naming is good. It's clear what's in common in these
flags and what's different.

> And if the whole posting tree is empty,then we could mark root page as leaf
> and remove all other pages in tree without any locking. Although, it could
> be a task for separate patch.

From the performance point of view, this is a very good idea. Both,
performance of VACUUM and performance of Scans. But doing so we risk
to leave some garbage pages in case of a crash. And I do not see how
to avoid these without unlinking pages one by one. I agree, that
leaving this trick for a separate patch is quite reasonable.

Best regards, Andrey Borodin.