Re: Are there tuning parameters that don't take effect immediately?

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От Michael Nolan
Тема Re: Are there tuning parameters that don't take effect immediately?
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Msg-id CAOzAquJa4XvkQefd2ZYK8BrNFyssGMgCwSgHeaUwnE-hxmmM3w@mail.gmail.com
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Ответ на Re: Are there tuning parameters that don't take effect immediately?  ("David G. Johnston" <david.g.johnston@gmail.com>)
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On Fri, Jun 12, 2015 at 4:52 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:
On Fri, Jun 12, 2015 at 4:37 PM, Michael Nolan <htfoot@gmail.com> wrote:
The only thing I can come up that's happened since last night was that we ran the nightly vacuum analyze on that database, but I did not change the statistics target.  


​The answer to your question is no, parameters changes are worse would take effect after a reboot - though most are used on the very next query that runs.

The vacuum would indeed likely account for the gains - there being significantly fewer ​dead/invisible rows to have to scan over and discard while retrieving the live rows that fulfill your query.

David J.


I wouldn't have said there was much activity in those tables since the previous day's vacuum, maybe a couple hundred rows changed or added in a table that has nearly 900,000 rows, and the other tables involved probably even less than that.  There may be one table with more activity, perhaps 20,000 row updates and maybe a few dozen new rows in a table that has 400,000 rows.  Maybe I need to manually analyze that table more often? 

Vacuum analyze verbose generate way too much output, is there a way to get some more straight forward numbers from an analyze?

I'm definitely not complaining about the improvement, I'm just trying to get a handle on what really caused it and whether I can improve it even further.
--
Mike Nolan


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