reason for default PGSTAT_ACTIVITY_SIZE
From my angle, it looks as if the default for PGSTAT_ACTIVITY_SIZE is
too small, or rather that it ought to be configurable at least, so
that longer current_query strings that are shown via
pg_stat_get_backend_activity() in the system view pg_stat_activity
aren't truncated.
The use case is to watch pg_stat_activity when troubleshooting a
busy/struggling live server which is building up a queue of long
running queries, to be able to see which of your SQL is most
problematic, and where it's coming from: We append a code reference as
a comment to all SQL that is sent by the ORM (we use a python web
application development framework, namely Django), in order to figure
out where it originates, which is otherwise tricky with SQL that is
generated by a translation layer - and this code reference is often
cut off because the string is limited.
Is there a good reason to set PGSTAT_ACTIVITY_SIZE at 256 and is my
only option to recompile the server? Is there a practical
limit/drawback to making the variable say 4 or 8 times the default?
I am referring to this post here:
http://archives.postgresql.org/pgsql-sql/2002-05/msg00087.php
and this one:
http://archives.postgresql.org/pgsql-novice/2004-02/msg00187.php
according to which recompiling would be the only option, but that was
a few years back so maybe it's a different story now.
Regards,
Frank
Le 05/01/2010 18:02, frank joerdens a �crit :
From my angle, it looks as if the default for PGSTAT_ACTIVITY_SIZE is
too small, or rather that it ought to be configurable at least, so
that longer current_query strings that are shown via
pg_stat_get_backend_activity() in the system view pg_stat_activity
aren't truncated.The use case is to watch pg_stat_activity when troubleshooting a
busy/struggling live server which is building up a queue of long
running queries, to be able to see which of your SQL is most
problematic, and where it's coming from: We append a code reference as
a comment to all SQL that is sent by the ORM (we use a python web
application development framework, namely Django), in order to figure
out where it originates, which is otherwise tricky with SQL that is
generated by a translation layer - and this code reference is often
cut off because the string is limited.Is there a good reason to set PGSTAT_ACTIVITY_SIZE at 256 and is my
only option to recompile the server? Is there a practical
limit/drawback to making the variable say 4 or 8 times the default?I am referring to this post here:
http://archives.postgresql.org/pgsql-sql/2002-05/msg00087.php
and this one:
http://archives.postgresql.org/pgsql-novice/2004-02/msg00187.php
according to which recompiling would be the only option, but that was
a few years back so maybe it's a different story now.
On current releases, it has a higher value (1024 IIRC). And it's a
configuration parameter on 8.4.
--
Guillaume.
http://www.postgresqlfr.org
http://dalibo.com
On Tue, Jan 5, 2010 at 6:24 PM, Guillaume Lelarge
<guillaume@lelarge.info> wrote:
[...]
Is there a good reason to set PGSTAT_ACTIVITY_SIZE at 256 and is my
only option to recompile the server? Is there a practical
limit/drawback to making the variable say 4 or 8 times the default?
[...]
On current releases, it has a higher value (1024 IIRC). And it's a
configuration parameter on 8.4.
A cool that's great news! We'll probably deal with this issue then by
going from 8.3->8.4 asap.
But I just grepped the 8.3 source tree for PGSTAT_ACTIVITY_SIZE and
it's not there? So the value/variable has a different name now?
Cheers,
Frank
Le 05/01/2010 20:36, Frank Joerdens a �crit :
On Tue, Jan 5, 2010 at 6:24 PM, Guillaume Lelarge
<guillaume@lelarge.info> wrote:
[...]Is there a good reason to set PGSTAT_ACTIVITY_SIZE at 256 and is my
only option to recompile the server? Is there a practical
limit/drawback to making the variable say 4 or 8 times the default?[...]
On current releases, it has a higher value (1024 IIRC). And it's a
configuration parameter on 8.4.A cool that's great news! We'll probably deal with this issue then by
going from 8.3->8.4 asap.But I just grepped the 8.3 source tree for PGSTAT_ACTIVITY_SIZE and
it's not there? So the value/variable has a different name now?
PGBE_ACTIVITY_SIZE since 8.2.
In 8.4, the GUC is named track_activity_query_size.
--
Guillaume.
http://www.postgresqlfr.org
http://dalibo.com