Re: Making aggregate deserialization (and WAL receive) functions slightly faster

On Sun, 12 Feb 2023 at 19:39, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I find this patch horribly dangerous.

I see LogicalRepApplyLoop() does something similar with a
StringInfoData. Maybe it's just scarier having an external function in
stringinfo.c which does this as having it increases the chances of
someone using it for the wrong thing.

> It could maybe be okay if we added the capability for StringInfoData
> to understand (and enforce) that its "data" buffer is read-only.
> However, that'd add overhead to every existing use-case.

I'm not very excited by that.  I considered just setting maxlen = -1
in the new function and adding Asserts to check for that in each of
the appendStringInfo* functions. However, since the performance gains
are not so great, I'll probably just drop the whole thing given
there's resistance.

David