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Re: PG as in-memory db? How to warm up and re-populate buffers? How to read in all tuples into memory?

From: Stefan Keller <sfkeller(at)gmail(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Claudio Freire <klaussfreire(at)gmail(dot)com>, postgres performance list <pgsql-performance(at)postgresql(dot)org>
Subject: Re: PG as in-memory db? How to warm up and re-populate buffers? How to read in all tuples into memory?
Date: 2012-02-29 15:28:25
Message-ID: CAFcOn28yyQgkw9iKfBcehFzR9s0_998TwzPhrhsuupMTtWHnmA@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
2012/2/29 Stefan Keller <sfkeller(at)gmail(dot)com>:
> 2012/2/29 Jeff Janes <jeff(dot)janes(at)gmail(dot)com>:
>>> It's quite possible the vacuum full is thrashing your disk cache due
>>> to maintainance_work_mem. You can overcome this issue with the tar
>>> trick, which is more easily performed as:
>>>
>>> tar cf /dev/null $PG_DATA/base
>>
>> But on many implementations, that will not work.  tar detects the
>> output is going to the bit bucket, and so doesn't bother to actually
>> read the data.
>
> Right.
> But what about the commands cp $PG_DATA/base /dev/null or cat
> $PG_DATA/base > /dev/null ?
> They seem to do something.

...or let's try /dev/zero instead /dev/null:
tar cf /dev/zero $PG_DATA/base

-Stefan

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Subject: Inefficient min/max against partition (ver 9.1.1)
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Subject: Re: PG as in-memory db? How to warm up and re-populate buffers? How to read in all tuples into memory?

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