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* track_activity_query_size note
@ 2012-05-24 12:16 Thom Brown <thom@linux.com>
0 siblings, 1 reply; 8+ messages in thread
From: Thom Brown @ 2012-05-24 12:16 UTC (permalink / raw)
To: pgsql-docs
Hi,
I attach a proposed change to the docs which points out that if the
size of track_activity_query_size is changed and the is server
restarted, it won't have any effect if query statistics are already
present.
Thanks
Thom
Attachments:
track_activity_query_size_note.patch (application/octet-stream, 615B) download
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 074afee..e02b94d 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4290,7 +4290,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
executing command for each active session, for the
<structname>pg_stat_activity</>.<structfield>query</> field.
The default value is 1024. This parameter can only be set at server
- start.
+ start and will also not take effect until any pre-existing statistics
+ are cleared.
</para>
</listitem>
</varlistentry>
* Re: track_activity_query_size note
@ 2012-05-24 12:39 Magnus Hagander <magnus@hagander.net>
parent: Thom Brown <thom@linux.com>
0 siblings, 1 reply; 8+ messages in thread
From: Magnus Hagander @ 2012-05-24 12:39 UTC (permalink / raw)
To: Thom Brown <thom@linux.com>; +Cc: pgsql-docs
On Thu, May 24, 2012 at 2:16 PM, Thom Brown <thom@linux.com> wrote:
> Hi,
>
> I attach a proposed change to the docs which points out that if the
> size of track_activity_query_size is changed and the is server
> restarted, it won't have any effect if query statistics are already
> present.
But aren't pg_stat_activity queries always cleared when you restart
the server - because they are all disconnected... And you can't change
track_activity_query_size without restarting.
--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: track_activity_query_size note
@ 2012-05-24 12:49 Thom Brown <thom@linux.com>
parent: Magnus Hagander <magnus@hagander.net>
0 siblings, 1 reply; 8+ messages in thread
From: Thom Brown @ 2012-05-24 12:49 UTC (permalink / raw)
To: Magnus Hagander <magnus@hagander.net>; +Cc: pgsql-docs
On 24 May 2012 13:39, Magnus Hagander <magnus@hagander.net> wrote:
> On Thu, May 24, 2012 at 2:16 PM, Thom Brown <thom@linux.com> wrote:
>> Hi,
>>
>> I attach a proposed change to the docs which points out that if the
>> size of track_activity_query_size is changed and the is server
>> restarted, it won't have any effect if query statistics are already
>> present.
>
> But aren't pg_stat_activity queries always cleared when you restart
> the server - because they are all disconnected... And you can't change
> track_activity_query_size without restarting.
But not pg_stat_statistics queries, which is where I should have
probably made the note. Restarting the server won't change the length
of the field if there's already data present in pg_stat_statistics,
but upon resetting them, the field is appropriately sized.
--
Thom
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: track_activity_query_size note
@ 2012-05-24 12:54 Magnus Hagander <magnus@hagander.net>
parent: Thom Brown <thom@linux.com>
0 siblings, 1 reply; 8+ messages in thread
From: Magnus Hagander @ 2012-05-24 12:54 UTC (permalink / raw)
To: Thom Brown <thom@linux.com>; +Cc: pgsql-docs
On Thu, May 24, 2012 at 2:49 PM, Thom Brown <thom@linux.com> wrote:
> On 24 May 2012 13:39, Magnus Hagander <magnus@hagander.net> wrote:
>> On Thu, May 24, 2012 at 2:16 PM, Thom Brown <thom@linux.com> wrote:
>>> Hi,
>>>
>>> I attach a proposed change to the docs which points out that if the
>>> size of track_activity_query_size is changed and the is server
>>> restarted, it won't have any effect if query statistics are already
>>> present.
>>
>> But aren't pg_stat_activity queries always cleared when you restart
>> the server - because they are all disconnected... And you can't change
>> track_activity_query_size without restarting.
>
> But not pg_stat_statistics queries, which is where I should have
> probably made the note. Restarting the server won't change the length
> of the field if there's already data present in pg_stat_statistics,
> but upon resetting them, the field is appropriately sized.
Uh, what's pg_stat_statistics?
--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: track_activity_query_size note
@ 2012-05-24 12:59 Thom Brown <thom@linux.com>
parent: Magnus Hagander <magnus@hagander.net>
0 siblings, 1 reply; 8+ messages in thread
From: Thom Brown @ 2012-05-24 12:59 UTC (permalink / raw)
To: Magnus Hagander <magnus@hagander.net>; +Cc: pgsql-docs
On 24 May 2012 13:54, Magnus Hagander <magnus@hagander.net> wrote:
> On Thu, May 24, 2012 at 2:49 PM, Thom Brown <thom@linux.com> wrote:
>> On 24 May 2012 13:39, Magnus Hagander <magnus@hagander.net> wrote:
>>> On Thu, May 24, 2012 at 2:16 PM, Thom Brown <thom@linux.com> wrote:
>>>> Hi,
>>>>
>>>> I attach a proposed change to the docs which points out that if the
>>>> size of track_activity_query_size is changed and the is server
>>>> restarted, it won't have any effect if query statistics are already
>>>> present.
>>>
>>> But aren't pg_stat_activity queries always cleared when you restart
>>> the server - because they are all disconnected... And you can't change
>>> track_activity_query_size without restarting.
>>
>> But not pg_stat_statistics queries, which is where I should have
>> probably made the note. Restarting the server won't change the length
>> of the field if there's already data present in pg_stat_statistics,
>> but upon resetting them, the field is appropriately sized.
>
> Uh, what's pg_stat_statistics?
s/pg_stat_statistics/pg_stat_statements/
--
Thom
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: track_activity_query_size note
@ 2012-05-24 13:03 Magnus Hagander <magnus@hagander.net>
parent: Thom Brown <thom@linux.com>
0 siblings, 1 reply; 8+ messages in thread
From: Magnus Hagander @ 2012-05-24 13:03 UTC (permalink / raw)
To: Thom Brown <thom@linux.com>; +Cc: pgsql-docs
On Thu, May 24, 2012 at 2:59 PM, Thom Brown <thom@linux.com> wrote:
> On 24 May 2012 13:54, Magnus Hagander <magnus@hagander.net> wrote:
>> On Thu, May 24, 2012 at 2:49 PM, Thom Brown <thom@linux.com> wrote:
>>> On 24 May 2012 13:39, Magnus Hagander <magnus@hagander.net> wrote:
>>>> On Thu, May 24, 2012 at 2:16 PM, Thom Brown <thom@linux.com> wrote:
>>>>> Hi,
>>>>>
>>>>> I attach a proposed change to the docs which points out that if the
>>>>> size of track_activity_query_size is changed and the is server
>>>>> restarted, it won't have any effect if query statistics are already
>>>>> present.
>>>>
>>>> But aren't pg_stat_activity queries always cleared when you restart
>>>> the server - because they are all disconnected... And you can't change
>>>> track_activity_query_size without restarting.
>>>
>>> But not pg_stat_statistics queries, which is where I should have
>>> probably made the note. Restarting the server won't change the length
>>> of the field if there's already data present in pg_stat_statistics,
>>> but upon resetting them, the field is appropriately sized.
>>
>> Uh, what's pg_stat_statistics?
>
> s/pg_stat_statistics/pg_stat_statements/
Ah, suddenly it makes sense.
And in that case yes, the docs changes should go under
pg_stat_statements, I believe.
--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: track_activity_query_size note
@ 2012-05-24 14:19 Tom Lane <tgl@sss.pgh.pa.us>
parent: Magnus Hagander <magnus@hagander.net>
0 siblings, 1 reply; 8+ messages in thread
From: Tom Lane @ 2012-05-24 14:19 UTC (permalink / raw)
To: Magnus Hagander <magnus@hagander.net>; +Cc: Thom Brown <thom@linux.com>; pgsql-docs
Magnus Hagander <magnus@hagander.net> writes:
> On Thu, May 24, 2012 at 2:59 PM, Thom Brown <thom@linux.com> wrote:
>>> I attach a proposed change to the docs which points out that if the
>>> size of track_activity_query_size is changed and the is server
>>> restarted, it won't have any effect if query statistics are already
>>> present.
> Ah, suddenly it makes sense.
> And in that case yes, the docs changes should go under
> pg_stat_statements, I believe.
But surely the statement is flat out wrong; or if it's not wrong,
there's a bug somewhere. We do not absorb the value of
track_activity_query_size from the stats file.
regards, tom lane
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: track_activity_query_size note
@ 2012-05-24 14:43 Thom Brown <thom@linux.com>
parent: Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 0 replies; 8+ messages in thread
From: Thom Brown @ 2012-05-24 14:43 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: Magnus Hagander <magnus@hagander.net>; pgsql-docs
On 24 May 2012 15:19, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Magnus Hagander <magnus@hagander.net> writes:
>> On Thu, May 24, 2012 at 2:59 PM, Thom Brown <thom@linux.com> wrote:
>>>> I attach a proposed change to the docs which points out that if the
>>>> size of track_activity_query_size is changed and the is server
>>>> restarted, it won't have any effect if query statistics are already
>>>> present.
>
>> Ah, suddenly it makes sense.
>
>> And in that case yes, the docs changes should go under
>> pg_stat_statements, I believe.
>
> But surely the statement is flat out wrong; or if it's not wrong,
> there's a bug somewhere. We do not absorb the value of
> track_activity_query_size from the stats file.
Hmm... well I think I may have misinterpreted the behaviour. What I
saw was the size of the query shown in pg_stat_statements remaining
unchanged after restarting the server with a new
track_activity_query_size value, but I'm guessing this is merely
because its representation remains unchanged. If I run the same query
with an extra condition on the end, it shows up as a separate row, but
not truncated to the same length as the previous query.
So I retract my proposed amendment as it's a falsehood. It was merely
an unexpected behaviour on my part. The truth is that pre-existing
queries listed in pg_stat_statements won't magically become less
truncated if track_activity_query_size is increased. That only
applies to new entries from that point that don't share the same query
signature.
--
Thom
^ permalink raw reply [nested|flat] 8+ messages in thread
end of thread, other threads:[~2012-05-24 14:43 UTC | newest]
Thread overview: 8+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2012-05-24 12:16 track_activity_query_size note Thom Brown <thom@linux.com>
2012-05-24 12:39 ` Magnus Hagander <magnus@hagander.net>
2012-05-24 12:49 ` Thom Brown <thom@linux.com>
2012-05-24 12:54 ` Magnus Hagander <magnus@hagander.net>
2012-05-24 12:59 ` Thom Brown <thom@linux.com>
2012-05-24 13:03 ` Magnus Hagander <magnus@hagander.net>
2012-05-24 14:19 ` Tom Lane <tgl@sss.pgh.pa.us>
2012-05-24 14:43 ` Thom Brown <thom@linux.com>
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