Re: debugging query to put message in pg logfile?

george young <gry(at)ll(dot)mit(dot)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.)

regards, tom lane