Re: [GENERAL] Can we Flush the Postgres Shared Memory ?

From: Merlin Moncure <mmoncure(at)gmail(dot)com>
To: Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>
Cc: raghu ram <raghuchennuru(at)gmail(dot)com>, Raghavendra <raghavendra(dot)rao(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-admin <pgsql-admin(at)postgresql(dot)org>, pgsql-general <pgsql-general(at)postgresql(dot)org>, pgsql novice <pgsql-novice(at)postgresql(dot)org>
Subject: Re: [GENERAL] Can we Flush the Postgres Shared Memory ?
Date: 2011-05-03 14:08:35
Message-ID: BANLkTim_LQ3oMVonYNX5-vbvw6d2A_M7vQ@mail.gmail.com
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On Tue, May 3, 2011 at 8:55 AM, Cédric Villemain
<cedric(dot)villemain(dot)debian(at)gmail(dot)com> wrote:
> 2011/5/3 Merlin Moncure <mmoncure(at)gmail(dot)com>:
>>
>> no it will not, or at least there is no guarantee it will be.  the
>> only way to reset the buffers in that sense is to restart the database
>> (and even then they might not be read from disk, because they could
>> sit in the o/s cache).  to force a read from the drive you'd have to
>> reboot the server, or at least shut it down and use a lot of memory
>> for some other purpose.
>
> with linux, you can : "echo 3 > /proc/sys/vm/drop_caches" for the OS cache
>

yeah -- good point. aside: does that also drop cache on the drive/raid card?

merlin

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