Simon Riggs <[EMAIL PROTECTED]> writes:
> So do you see a problem scenario like this?

> A, B and C separate backends:
> A1 Reads page, some row versions are *not* marked LP_DELETE but will be
> later when A2 happens
>       B1 VACUUM removes dead rows, just happens to be all of them
>       B2 Recycles page into FSM
>               C1 Inserts new data into old page
> A2 Attempts to update old page to notify about dead rows (UGH!)

Can't happen; a page cannot be recycled until all concurrent
transactions are gone.  In any case, the LP_DELETE marking code will
certainly take care to check that the entries it's trying to mark
are still the same ones it meant to mark.

                        regards, tom lane

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