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From: george young <gry@ll.mit.edu>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-sql@postgresql.org
Subject: Re: debugging query to put message in pg logfile?
Date: Fri, 5 Mar 2004 10:23:45 -0500
Message-ID: <20040305102345.60293483.gry@ll.mit.edu> (raw)
In-Reply-To: <28982.1078436101@sss.pgh.pa.us>
References: <20040304153219.210f3648.gry@ll.mit.edu>
	<28982.1078436101@sss.pgh.pa.us>

On Thu, 04 Mar 2004 16:35:01 -0500
Tom Lane <tgl@sss.pgh.pa.us> threw this fish to the penguins:

> george young <gry@ll.mit.edu> writes:
> > I've started putting debugging queries like:
> >    select "opwin.py: committing step signoff"
> > in my app, just to have an entry in the postgres logfile.
> 
> > Is there some cheaper (or more appropriate) sql statement that will show
> > up in the postgres log?
> 
> You could just send SQL comments:
> 
> 	-- opwin.py: committing step signoff
> 
> One advantage of this is that you can merge the comments with actual
> commands, thus not incurring even a network round-trip time for them.
> If you do send it separately, it will act like an empty query string.
> 
> People tend not to think of this because psql strips -- comments before
> sending commands.  But I believe all the lower-level libraries will pass
> them through.  (If you need to pass loggable comments through psql, I
> think the /* ... */ form will work.)

Alas no:

Python 2.3.3 (#1, Jan  3 2004, 07:17:11) 
[GCC 3.3.2] on linux2
>>> import pgdb
>>> db=pgdb.connect(host='ivy:5433',database='pigtest')
>>> c=db.cursor()
>>> cur.execute('-- the rain')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/local/lib/python2.3/site-packages/pgdb.py", line 189, in execute
    self.executemany(operation, (params,))
  File "/usr/local/lib/python2.3/site-packages/pgdb.py", line 210, in executemany
    raise OperationalError, "internal error in '%s'" % sql
pgdb.OperationalError: internal error in '-- the rain'

Likewise for /* comments */. :-(

I'll continue this on the pygresql mailing list; and I guess stick to
"select 'comment text'" for now...

Thanks,

   -- George Young

-- 
"Are the gods not just?"  "Oh no, child.
What would become of us if they were?" (CSL)



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