Re: heap_page_prune comments

On Nov 2, 2011, at 11:27 AM, Robert Haas wrote:
> The following comment - or at least the last sentence thereof -
> appears to be out of date.
>
> /*
> * XXX Should we update the FSM information of this page ?
> *
> * There are two schools of thought here. We may not want to update FSM
> * information so that the page is not used for unrelated
> UPDATEs/INSERTs
> * and any free space in this page will remain available for further
> * UPDATEs in *this* page, thus improving chances for doing HOT updates.
> *
> * But for a large table and where a page does not receive
> further UPDATEs
> * for a long time, we might waste this space by not updating the FSM
> * information. The relation may get extended and fragmented further.
> *
> * One possibility is to leave "fillfactor" worth of space in this page
> * and update FSM with the remaining space.
> *
> * In any case, the current FSM implementation doesn't accept
> * one-page-at-a-time updates, so this is all academic for now.
> */
>
> The simple fix here is just to delete that last sentence, but does
> anyone think we ought to do change the behavior, now that we have the
> option to do so?

The fillfactor route seems to make the most sense here... it certainly seems to be the least surprising behavior.
--
Jim C. Nasby, Database Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net