Robert Haas <robertmh...@gmail.com> writes: > On Sat, Nov 12, 2016 at 10:28 AM, Andres Freund <and...@anarazel.de> wrote: >> On 2016-08-30 07:38:10 -0400, Tom Lane wrote: >>> I think this is probably wrong, or at least very dangerous to remove. >>> The reason for the feature is that the slot may continue to point at >>> the tuple after the scan has moved on.
>> FWIW, that's not safe to assume in upper layers *anyway*. If you want to >> do that, the slot has to be materialized, and that'd make a local >> copy. If you don't materialize tts_values/isnull can point into random >> old memory (common e.g. for projections and virtual tuples in general). > So, I think you are arguing in favor of proceeding with this patch? I don't believe Andres' claim anyway. There are certainly cases where an allegedly-valid slot could be pointing at garbage, but table scans aren't one of them, precisely because of the pin held by the slot. It would take a fairly wide-ranging code review to convince me that it's okay to lose that mechanism. regards, tom lane -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers