Thread: Need a debugging tip or two
I've just started fooling with some modifications to the backend. I'm new at doing this in PG, so I'm blundering I'm sure. In any event when I start the backend standalone (i.e. running the 'postgres -D ....' command, it seems I have to be the root or postgres root user because of file permissions. But I want access to the database of my normal username, which is 'kevin'. Questions: have I identified the problem right? Is that why I can't see my tables? If so, is there a way to change databases, given that the \ commands don't work in the backend? Or am I just going at this all wrong in some way? ++ kevin -- Kevin O'Gorman (805) 650-6274 mailto:kogorman@pacbell.net Permanent e-mail forwarder: mailto:Kevin.O'Gorman.64@Alum.Dartmouth.org At school: mailto:kogorman@cs.ucsb.edu Web: http://www.cs.ucsb.edu/~kogorman/index.html Web: http://trixie.kosman.via.ayuda.com/~kevin/index.html "There is a freedom lying beyond circumstance, derived from the direct intuition that life can be grounded upon its absorption in what is changeless amid change" -- Alfred North Whitehead
Kevin O'Gorman writes: > In any event when I start the backend standalone (i.e. running > the 'postgres -D ....' command, it seems I have to be the root > or postgres root user because of file permissions. Yup. > But I want access to the database of my normal username, which is > 'kevin'. postgres [options] dbname > Questions: have I identified the problem right? Is that why I > can't see my tables? If so, is there a way to change databases, > given that the \ commands don't work in the backend? Not sure when a \ command *changed* a database last time. > Or am I just going at this all wrong in some way? There's probably little reason to start a backend standalone. If you want to do stock-of-the-trade debugging you simply start a postmaster, then psql (or whatever floats your boat), and attach gdb to the resulting backend process. -- Peter Eisentraut peter_e@gmx.net http://yi.org/peter-e/
Peter Eisentraut <peter_e@gmx.net> writes:
> There's probably little reason to start a backend standalone. If you want
> to do stock-of-the-trade debugging you simply start a postmaster, then
> psql (or whatever floats your boat), and attach gdb to the resulting
> backend process.
Right, that's what I always do (unless I have to debug a crash at initdb
time :-(). A tip here is that you can even debug backend-startup-time
problems this way, and no you don't have to be superhumanly quick on the
trigger: you set PGOPTIONS="-W n" in the environment of psql. This
will cause an n-second sleep() call very early in the backend startup
process. I find 30 seconds plenty of time to run ps, start gdb, and
attach. You can also throw in things like "-d2" to crank up the
postmaster log level for just the backend under test.
I thought this lore was in the developer's FAQ already, but I don't
see it there at the moment. Bruce, is it lurking someplace else?
regards, tom lane
I see the mention of -w in the main FAQ. > Peter Eisentraut <peter_e@gmx.net> writes: > > There's probably little reason to start a backend standalone. If you want > > to do stock-of-the-trade debugging you simply start a postmaster, then > > psql (or whatever floats your boat), and attach gdb to the resulting > > backend process. > > Right, that's what I always do (unless I have to debug a crash at initdb > time :-(). A tip here is that you can even debug backend-startup-time > problems this way, and no you don't have to be superhumanly quick on the > trigger: you set PGOPTIONS="-W n" in the environment of psql. This > will cause an n-second sleep() call very early in the backend startup > process. I find 30 seconds plenty of time to run ps, start gdb, and > attach. You can also throw in things like "-d2" to crank up the > postmaster log level for just the backend under test. > > I thought this lore was in the developer's FAQ already, but I don't > see it there at the moment. Bruce, is it lurking someplace else? > > regards, tom lane > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026