From: | Chris Bitmead <chrisb(at)nimrod(dot)itg(dot)telstra(dot)com(dot)au> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Postgres Hackers List <hackers(at)postgresql(dot)org> |
Subject: | Re: postgres fe/be protocol |
Date: | 2000-07-11 00:53:04 |
Message-ID: | 396A6FF0.BC320BAF@nimrod.itg.telecom.com.au |
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Lists: | pgsql-hackers |
Tom Lane wrote:
>
> Chris Bitmead <chris(at)bitmead(dot)com> writes:
> > I inserted some debug into libpq, then I ran psql, and I noticed that
> > there are two 'Z' "Ready for query" messages sent after each query. Is
> > there a reason for that? Is it a bug?
>
> I'm pretty sure the backend sends only one 'Z' per query cycle. Are you
> watching the outgoing requests too? Maybe psql is sending an extra
> empty query. (It didn't use to do that, but maybe it does after Peter's
> recent work on it...)
I put in a printf in parseInput in fe-exec.c in libpq, straight after it
reads the id. This is only going to see messages incoming to the front
end.
I also had a break-point on PQexec and it was only called once per
query.
For each query that I input to psql, everything looked normal except
for the two 'Z's.
Ok, I've just done it again on another platform with the same result.
This
is what I see...
chrisb=# select * from a;
P
T
D
C
Z
Z
aa | bb | cc
-----+-----+-----
aaa | bbb | ccc
(1 row)
We've got the P - select results, T - describe output D - one output
tuple,
C - complete Z - ready for input.
It all seems sensible except for the two Z's.
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