Re: TOAST performance (was Re: [GENERAL] Delete Perform

> If "pre-page WAL write" means the value of the page before the current
> changes, then there is generally another reason for writing it out.

Bruce, "*pre*-page" is confusing - we write "after-change" page
image to WAL.

> When the system comes back up, we need to do a rollback on
> transaction B since it did not commit and we need the "pre-page"
> to know how to undo the change for B that got saved in step 6 above.

Brian, PGSQL still uses non-overwriting storage manager -
removing rows inserted by aborted transactions is not required.

Vadim