On Thu, Sep 25, 2014 at 9:21 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> The top issue on my agenda is figuring out a way to get rid of the
> extra SortSupport object.
Really? I'm surprised. Clearly the need to restart heap tuple copying
from scratch, in order to make the datum1 representation consistent,
rather than abandoning datum1 for storing abbreviated keys or pointers
entirely is a very important aspect of whether or not we should change
that. In turn, that's something that's going to (probably
significantly) affect the worst case.
Do you have an opinion on that? If you want me to start from scratch,
and then have a consistent datum1 representation, and then be able to
change the structure of comparetup_heap() as you outline (so as to get
rid of the extra SortSupport object), I can do that. My concern is the
regression. The datum1 pointer optimization appears to matter very
little for pass by value types (traditionally, before abbreviated
keys), and so I have a hard time imagining this working out.
--
Peter Geoghegan