Re: Why doesn't GiST VACUUM require a super-exclusive lock, like nbtree VACUUM?

One thing I think we could add to the patches is to adapt the 10-years-old comment below with notice about IOS:

/*
* We save the LSN of the page as we read it, so that we know whether it
* safe to apply LP_DEAD hints to the page later. This allows us to drop
* the pin for MVCC scans, which allows vacuum to avoid blocking.
*/
so->curPageLSN = BufferGetLSNAtomic(buffer);

Also, I think it is a good idea to add "Assert(!scan->xs_want_itup);" to gistkillitems.

Best regards,

Mikhail.