Re: [HACKERS] Planning final assault on query length limits

Vadim Mikheev <vadim@krs.ru> writes:
>> a fairly localized task, if I'm not greatly mistaken about it.  And
>            ^^^^^^^^^^^^^^
> I'm not sure. Seems that we'll have to change heap_getattr:
> if a column crosses page boundary then we'll have to re-construct
> it in memory and pfree it after using...

I was thinking more along the lines of reconstructing the whole tuple
in palloc'd memory and leaving heap_getattr as-is.  Otherwise we have
problems with the system relations whose tuples are accessed as C
structs.  You'd need to somehow guarantee that those tuples are never
split if you do it as above.

Of course, that just moves the palloc/pfree bookkeeping problem down
a level; it's still going to be tricky to avoid storage leaks.
We might be able to get some win from storing reassembled tuples in
TupleTableSlots, though.

>> there's plenty of time left before 7.0.  So this seems like a perfect
>> project for someone who wants to learn more about the backend and has
>> some time to spend doing so.

> And we always ready to help...

Right.  Questions can be answered.
        regards, tom lane