Re: V3 protocol gets out of sync on messages that cause allocation

Tom Lane wrote:
> I wrote:
>
>>Yeah. The intent of the protocol design was that the recipient could
>>skip over the correct number of bytes even if it didn't have room to
>>buffer them, but the memory allocation mechanism in the backend makes
>>it difficult to actually do that. Now that we have PG_TRY, though,
>>it might not be out of reach to do it right.
>
>
> And indeed it wasn't. Patch committed.

Thanks!

Re your commit comment:

> I'm a bit dubious that this is a real problem, since the client likely
> doesn't have any more space available than the server, but it's not hard
> to make it behave according to the protocol intention.

It's quite possible that the client isn't keeping the whole parameter in
memory. For example, JDBC has a method that allows a streamable
parameter (with prespecified length) to be set, and the stream contents
could be coming from disk or computed on demand. That is actually where
I came across the problem in the first place.

-O