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* excessive WAL activity
@ 2013-06-19 23:22 Sean Dillon <sean@dillonsoftware.com>
0 siblings, 1 reply; 3+ messages in thread
From: Sean Dillon @ 2013-06-19 23:22 UTC (permalink / raw)
To: pgsql-admin
Just turned on WAL archiving to an S3 bucket for a small database - total size of perhaps 2-4G. After turning on achiving, we're seeing WAL logs written to S3 at the rate of about 1G every 3 minutes. That seems completely unreasonable given usage of the db. I can even see that nearly nothing is happening with this:
select datname, usename, procpid, client_addr, waiting, query_start, current_query from pg_stat_activity;
Nearly every time I run that, all 20 connections have current_query = '<IDLE>'. Does current_query include inserts, updates, and deletes or just select statements?
Any ideas what to look for or how to solve this?
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^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: excessive WAL activity
@ 2013-06-20 14:33 bricklen <bricklen@gmail.com>
parent: Sean Dillon <sean@dillonsoftware.com>
0 siblings, 1 reply; 3+ messages in thread
From: bricklen @ 2013-06-20 14:33 UTC (permalink / raw)
To: Sean Dillon <sean@dillonsoftware.com>; +Cc: pgsql-admin
On Wed, Jun 19, 2013 at 4:22 PM, Sean Dillon <sean@dillonsoftware.com>wrote:
> Just turned on WAL archiving to an S3 bucket for a small database - total
> size of perhaps 2-4G. After turning on achiving, we're seeing WAL logs
> written to S3 at the rate of about 1G every 3 minutes. That seems
> completely unreasonable given usage of the db. I can even see that nearly
> nothing is happening with this:
>
> select datname, usename, procpid, client_addr, waiting, query_start,
> current_query from pg_stat_activity;
>
> Nearly every time I run that, all 20 connections have current_query =
> '<IDLE>'. Does current_query include inserts, updates, and deletes or just
> select statements?
>
> Any ideas what to look for or how to solve this?
>
Can you show the results from:
SELECT name, current_setting(name), source
FROM pg_settings
WHERE source NOT IN ('default', 'override')
UNION ALL
SELECT 'version' as name, version(), null;
Perhaps there is a setting there (like archive_timeout) which could lead to
an answer. In your $PGDATA/pg_xlog directory, look at the timestamps of the
WAL segments, are there lots of files generated per minute?
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: excessive WAL activity
@ 2013-06-21 07:54 Albe Laurenz <laurenz.albe@wien.gv.at>
parent: bricklen <bricklen@gmail.com>
0 siblings, 0 replies; 3+ messages in thread
From: Albe Laurenz @ 2013-06-21 07:54 UTC (permalink / raw)
To: bricklen *EXTERN* <bricklen@gmail.com>; Sean Dillon <sean@dillonsoftware.com>; +Cc: pgsql-admin
bricklen wrote:
> On Wed, Jun 19, 2013 at 4:22 PM, Sean Dillon <sean@dillonsoftware.com> wrote:
>> Just turned on WAL archiving to an S3 bucket for a small database - total size of perhaps 2-4G.
>> After turning on achiving, we're seeing WAL logs written to S3 at the rate of about 1G every 3
>> minutes. That seems completely unreasonable given usage of the db. I can even see that nearly
>> nothing is happening with this:
>>
>> select datname, usename, procpid, client_addr, waiting, query_start, current_query from
>> pg_stat_activity;
>>
>> Nearly every time I run that, all 20 connections have current_query = '<IDLE>'. Does
>> current_query include inserts, updates, and deletes or just select statements?
>>
>> Any ideas what to look for or how to solve this?
>
> Can you show the results from:
>
> SELECT name, current_setting(name), source
> FROM pg_settings
> WHERE source NOT IN ('default', 'override')
> UNION ALL
> SELECT 'version' as name, version(), null;
>
>
> Perhaps there is a setting there (like archive_timeout) which could lead to an answer. In your
> $PGDATA/pg_xlog directory, look at the timestamps of the WAL segments, are there lots of files
> generated per minute?
Also, it might be good to check how much is really going on.
Try log_statement=all and see how much gets logged.
Yours,
Laurenz Albe
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^ permalink raw reply [nested|flat] 3+ messages in thread
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2013-06-19 23:22 excessive WAL activity Sean Dillon <sean@dillonsoftware.com>
2013-06-20 14:33 ` bricklen <bricklen@gmail.com>
2013-06-21 07:54 ` Albe Laurenz <laurenz.albe@wien.gv.at>
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