Re: A bad behavior under autocommit off mode

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Tom, did you have any thought of adding the ability to ask for reports
> on GUC variables on every query return?

That seems excessive. There is a case for reporting autocommit (if
we don't decide to remove it altogether, which is still an open
argument). I have not heard any complaints suggesting that we need any
others.

A fixed commitment to report xact status will cost us one byte added to
Z messages. If we add a commitment to report autocommit status, we
could choose to pack that bit into the same byte as xact status (still
only three bits used...). A slightly more forward-looking approach
would be to decree that Z messages carry labeled status bytes, ie, pairs
of <label> <status> bytes, which makes total cost 4 bytes to transmit
xact state and autocommit state. But if we want to say that we'll
transmit *any* darn random GUC variable you want to hear about, I don't
think we can use a compact encoding of this sort; instead we're talking
about sending the whole GUC variable name and string value as label and
value. In other words the Z message starts to look like
Z X a c t s t a t u s \0 i d l e \0 a u t o c o m m i t \0 o f f \0
and somewhere around here my concern for connection bandwidth kicks in.
A 10X increase in bytes sent is a bit much to cater to hypothetical
needs.

regards, tom lane