Re: libpq and prepared statements progress for 8.0

Greg Stark wrote:

> I was pretty shocked when I heard that JDBC implements the low level protocol
> itself. It seems like a dead-end strategy to me. Any new protocol innovations
> need to be implemented in every driver. Every implementation gets the chance
> to reimplement the same bugs and same inefficiencies over and over again.

There *are* benefits to implementing the protocol directly. First on my
personal list is that our Java application would not be able to use
postgresql at all if the driver required JNI/libpq.

There are also some things in the JDBC API that seem hard to map to the
current libpq API, e.g. streaming parameter data from a Java stream
without taking an intermediate copy.

The protocol implementation is not really all that complex. The
implementation for both V2 and V3 weighs in at ~6k lines of Java out of
~38k total, and much of that is connection-state juggling that we'd have
to do anyway if using libpq (working out when to send BEGIN, breaking up
multiple-statement queries into individual statements and matching the
results up, managing portal state, etc).

-O