Re: Performance with the new security release? - Mailing list pgsql-hackers

On 13-04-22 04:41 PM, Anne Rosset wrote:
> Hi Steve,
> Yes I see these messages in our log. Is there a solution to this?
> Thanks,
> Anne

A manual analyze of the effected tables should work and give you updated 
statistics.  If your problem is just statistics then that should help.
A manual vacuum will , unfortunately, behave like the auto-vacuum. The 
only way to get vacuum past this (until this issue is fixed) is for 
vacuum to be able to get that exclusive lock.   If there are times of 
the day your database is less busy you might have some luck turning off 
auto-vacuum on these tables  and doing manual vacuums during those times.




> -----Original Message-----
> From: Steve Singer [mailto:steve@ssinger.info]
> Sent: Monday, April 22, 2013 1:26 PM
> To: Anne Rosset
> Cc: pgsql-hackers@postgresql.org
> Subject: Re: [HACKERS] Performance with the new security release?
>
> On 13-04-22 04:15 PM, Anne Rosset wrote:
>> Hi Steve,
>> Thanks for your reply.
>> We are now running  9.0.13. Before it was 9.0.7.
>> How can I find out if we are running into this issue: "ie if
>> statistics are no longer being updated because analyze can't get the exclusive lock for truncation"?
> This issue is discussed in the thread
> http://www.postgresql.org/message-id/CAMkU=1xYXOJp=jLAASPdSAqab-HwhA_tnRhy+JUe=4=b=v3KoQ@mail.gmail.com
>
> If your seeing messages in your logs of the form:
>
> automatic vacuum of table XXX.YYY cannot (re)acquire exclusive lock for truncate scan"
>
> then you might be hitting this issue.
>
>
>> I will dig into our logs to see for the query times.
>> Thanks,
>> Anne
>>
>> -----Original Message-----
>> From: Steve Singer [mailto:steve@ssinger.info]
>> Sent: Monday, April 22, 2013 12:59 PM
>> To: Anne Rosset
>> Cc: pgsql-hackers@postgresql.org
>> Subject: Re: [HACKERS] Performance with the new security release?
>>
>> On 13-04-22 01:38 PM, Anne Rosset wrote:
>>> Hi,
>>> We are seeing some overall performance degradation in our application
>>>     since we installed the security release. Other commits were also
>>> done at the same time in the application so we don't know yet if the
>>>     degradation has any relationship with the security release.
>>>
>>>     While we are digging into this, I would like to know if it is possible
>>>     that the release has some impact on performance. After reading this
>>>     "It was created as a side effect of a refactoring effort to make
>>>     establishing new connections to a PostgreSQL server faster, and the
>>>     associated code more maintainable.", I am thinking it is quite possible.
>>>
>>>     Please let me know. Thanks,
>> Exactly which version of PostgreSQL are you running? (we released security update releases for multiple PG
versions). Also which version were you running before?
 
>>
>> There were some changes to analyze/vacuum in the previous set of minor releases that could cause performance issues
insome cases (ie if statistics are no longer being updated because analyze can't get the
 
>> exclusive lock for truncation).   There might be other unintended
>> performance related changes.
>>
>> Are all queries taking longer or only some?  Can you find any sort of pattern that might help narrow the issue?
>>
>> Steve
>>
>>>     Anne
>>>
>>>
>>
>
>