pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Iwata, Aya <iwata.aya@jp.fujitsu.com>
Cc: Jamison, Kirk <k.jamison@jp.fujitsu.com>
Cc: Nagaura, Ryohei <nagaura.ryohei@jp.fujitsu.com>
Cc: Jacob Champion <pchampion@pivotal.io>
Cc: Jim Doty <jdoty@pivotal.io>
Cc: PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
Cc: nagata@sraoss.co.jp <nagata@sraoss.co.jp>
Cc: Haribabu Kommi <kommi.haribabu@gmail.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Subject: Re: libpq debug log
Date: Mon, 04 Mar 2019 22:25:39 -0500
Message-ID: <5008.1551756339@sss.pgh.pa.us> (raw )
In-Reply-To: <CA+TgmobGvUKiNQfh-4GzTWxoD1qX63D3_W3O+fnzBXBCiRSo=g@mail.gmail.com >
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<CA+TgmobviA3E6JH4ohq50FvvL8Lo1=jGKR3t2L196J3CjVeQJg@mail.gmail.com >
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Robert Haas <robertmhaas@gmail.com> writes:
> The basic idea being:
> - Each line is a whole message.
> - The line begins with <<< for a message received and >>> for a message sent.
+1, though do we really need to repeat the direction marker thrice?
> - Strings in single quotes are those sent/received as a fixed number of bytes.
> - Strings in double quotes are those sent/received as a string.
> - 4-byte integers are printed unadorned.
> - 2-byte integers are prefixed by #.
> - I guess 1-byte integers would need some other prefix, maybe @ or ##.
I doubt that anybody gives a fig for those distinctions, except when
they're writing actual code that speaks the protocol --- and I do not
think that that's the target use-case. So strings and integers seem
like plenty. I'd also suggest that just because the protocol has
single-letter codes for message types doesn't mean that average users
have memorized those codes; and that framing data like the message
length is of no interest.
In short, rather than
<<< 'T' 101 4 "Schema" 2615 #2 19 #64 -1 #0 "Name" 1259 #2 19 #64 -1 #0 "Owner" 0 #0 19 #64 -1 #0
I'd envision something more like
< RowDescription "Schema" 2615 2 19 64 -1 0 "Name" 1259 2 19 64 -1 0 "Owner" 0 0 19 64 -1 0
> But I still don't really see a need for different levels or whatever.
> I mean, you either want a dump of all of the protocol traffic, or you
> don't, I think. Or maybe I am confused as to what the goal of all
> this really is.
Yeah, me too. But a lot of this detail would only be useful if you
were trying to diagnose something like a discrepancy between the server
and libpq as to the width of some field. And the number of users for
that can be counted without running out of fingers. I think what would
be of use for a trace facility is as high-level a view as possible of
the message contents.
Or, in other words: a large part of the problem with the existing PQtrace
facility is that it *was* designed to help debug libpq itself, and that
use-case is no longer very interesting. We should assume that the library
knows how to parse protocol messages.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, robertmhaas@gmail.com, iwata.aya@jp.fujitsu.com, k.jamison@jp.fujitsu.com, nagaura.ryohei@jp.fujitsu.com, pchampion@pivotal.io, jdoty@pivotal.io, nagata@sraoss.co.jp, kommi.haribabu@gmail.com, peter.eisentraut@2ndquadrant.com
Subject: Re: libpq debug log
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