Re: session id and global storage

Rodrigo De Leon wrote:

Hi, I cant find any function, which tells me something like session
id. Is there something like that? I need it in my AM, because I need
to know, if something which I wrote in file was written in this
current session or previously.

How about
select procpid||' '||backend_start from pg_stat_activity;
Yours,
Laurenz Albe

Something like this would be maybe possible, but this select can
return more rows, when the user is connected with more instances...

You could do this:

SELECT procpid||' '||backend_start
FROM pg_stat_activity
WHERE datname = current_database()
AND usename = session_user
AND client_addr = inet_client_addr()
AND client_port = inet_client_port();

That's pretty roundabout. We already expose (hex coded) pid.starttime as
a session identifier in log_line_prefix (it's the %c escape) so I don't
see any reason not to provide either the same thing directly in a
function, or at least to expose the backend pid.

If you need it in backend C code, the data can be fetched from MyProcPid
and MyProcPort->session_start.tv_sec

cheers

andrew

That's pretty roundabout. We already expose (hex coded) pid.starttime as
a session identifier in log_line_prefix (it's the %c escape) so I don't
see any reason not to provide either the same thing directly in a
function, or at least to expose the backend pid.

That would be nice.

Andrew Dunstan <andrew@dunslane.net> writes:

Rodrigo De Leon wrote:

You could do this:

SELECT procpid||' '||backend_start
FROM pg_stat_activity
WHERE datname = current_database()
AND usename = session_user
AND client_addr = inet_client_addr()
AND client_port = inet_client_port();

That's pretty roundabout.

Indeed. Use pg_backend_pid() instead:

SELECT whatever FROM pg_stat_activity WHERE procpid = pg_backend_pid();

A difficulty with this in existing releases is that pg_stat_activity
lags behind reality, so that you won't see your session listed in it
until you've been connected at least half a second or so. 8.2 won't
have that problem.

regards, tom lane