Re: [HACKERS] HOT WIP Patch - version 2

On 2/20/07, Bruce Momjian <bruce@momjian.us> wrote:

Pavan Deolasee wrote:
> When following a HOT-update chain from the index fetch, if we notice that
> the root tuple is dead and it is HOT-updated, we try to prune the chain to
> the smallest possible length. To do that, the share lock is upgraded to an
> exclusive lock and the tuple chain is followed till we find a
> live/recently-dead
> tuple. At that point, the root t_ctid is made point to that tuple. In order

I assume you meant recently-dead here, rather than live/recently-dead,
because we aren't going to change live ctids, right?

We are not changing the tids here, but only pruning the HOT-update chain.
After pruning, the root->t_ctid points to the oldest tuple that might be
visible to any backend. The live tuples are still identified by their
original tid and index reachable from the root tuple.