Re: Bug in VACUUM FULL ?

On 3/10/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>
> Also, we know this case works because it already is working: in the
> situation where VACUUM happens to visit and remove the DEAD tuple(s)
> before reaching the RECENTLY_DEAD tuples that link forward to them,
> it treats the RECENTLY_DEAD tuples as a disconnected chain and moves
> them as-is. I saw tons of this in the traces I was making today, and
> it doesn't seem to create any bad effects. (My attention was drawn to
> it because I saw move_chain_tuple being used to move single-member
> chains, which looks impossible when you first look at the code --- the
> is-it-a-chain test seems to ensure that we can link either forward or
> backward. But not so if t_ctid points to an already-removed tuple.)
>
>
Oh. So thats the corner case which I missed. This would probably
explain how we could miss marking an offset free and thus not remove
the corresponding index entry.

Thanks,
Pavan

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