David Rowley <dgrowleyml@gmail.com> writes: > Tom commited some changes to appendStringInfoVA a few weeks ago which > allows it to return the required buffer size if the current buffer is not > big enough.
> On looking at appendPQExpBufferVA I'm thinking it would be nice if it could > make use of the new pvsnprintf function to bring the same potential > performance improvement in to there too.
Uh ... it does contain pretty much the same algorithm now. We can't simply use pvsnprintf there because exit-on-error is no good for libpq's purposes, so unless we want to rethink that, a certain amount of code duplication is unavoidable. But they both understand about C99 vsnprintf semantics now.
I only just noticed the changes you made to appendPQExpBufferVA().
I had wondered if making pvsnprintf return int instead of size_t and having it return -1 if there are problems, then letting the caller deal with those, but I'm starting to see why you did it the way you did it... There's also quite a few subtle differences with things like max allocation size that would have to be dealt with differently I guess.
I'm low on ideas on how to improve things much around here for now, but for what it's worth, I did create a patch which changes unnecessary calls to appendPQExpBuffer() into calls to appendPQExpBufferStr() similar to the recent one for appendStringInfo and appendStringInfoString.
