Re: Query gone wild

on 1/29/03 11:11 AM, Tom Lane at tgl(at)sss(dot)pgh(dot)pa(dot)us wrote:

> Neil Conway <neilc(at)samurai(dot)com> writes:
>> On Wed, 2003-01-29 at 12:58, Garo Hussenjian wrote:
>>> Is there any way to view the query
>>> that is being run from knowing a process id?
>
>> You can use the pg_stat_activity view in PostgreSQL 7.2 and later -- see
>
> However, he probably doesn't have stats_command_string turned on, or
> he'd already be aware of pg_stat_activity :-(. So this isn't much help
> if the problem is to determine what an already-running query is.
>
> Another possibility is to attach to the runaway process with a debugger
> and print debug_query_string. For example, with gdb:
>
> $ gdb /path/to/postgres-executable
> gdb> attach PID-OF-PROCESS
> gdb> p debug_query_string
> gdb> quit
>
Thanks, Tom.

Here's what I got going...

semerjia% gdb usr/local/pgsql/bin/postmaster
GNU gdb 4.18
< MORE GDB STUFF... >
(gdb) attach 43179
Attaching to program: /usr/home/semerjia/usr/local/pgsql/bin/postmaster,
process 43179
Reading symbols from /usr/lib/libz.so.2...done.
Reading symbols from /usr/lib/libcrypt.so.2...done.
Reading symbols from /usr/lib/libm.so.2...done.
Reading symbols from /usr/lib/libutil.so.3...done.
Reading symbols from /usr/lib/libreadline.so.4...done.
Reading symbols from /usr/lib/libc.so.4...done.
Reading symbols from /usr/lib/libncurses.so.5...done.
Reading symbols from /usr/libexec/ld-elf.so.1...done.
0x28346088 in read () from /usr/lib/libc.so.4
(gdb) p debug_query_string
$1 = 138514480
(gdb)

> This should work unless you are running a stripped backend executable.
> (On many systems, the "file" command can tell you whether an executable
> has been stripped of debug symbols.)

I can't tell if this worked... What is '$1 = 138514480'. After running gdb,
the process STAT for 42179 changed from R to T so I kill'ed it...

>
> regards, tom lane
>
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