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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: 2012-03-01 22:52:48
Message-ID: CAFcOn2-bhKg3hbLMUDK1=_9FookxP6xbqeubzO9uwcP=dqnwyw@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
2012/3/1 Jeff Janes <jeff(dot)janes(at)gmail(dot)com>:
> On Tue, Feb 28, 2012 at 3:46 PM, Stefan Keller <sfkeller(at)gmail(dot)com> wrote:
>> 2012/2/28 Claudio Freire <klaussfreire(at)gmail(dot)com>:
>>>
>>> In the OP, you say "There is enough main memory to hold all table
>>> contents.". I'm assuming, there you refer to your current system, with
>>> 4GB memory.
>>
>> Sorry for the confusion: I'm doing these tests on this machine with
>> one table (osm_point) and one country. This table has a size of 2.6GB
>> and 10 million tuples. The other machine has to deal with at least 5
>> tables in total and will be hold more than one country plus routing
>> etc..
>
> What is your shared_buffers set to?  2.6GB is uncomfortably close to
> 4GB, considering the computer has other things it needs to use memory
> for as well.

These are the current modified settings in postgresql.conf:
shared_buffers = 128MB
work_mem = 3MB
maintenance_work_mem = 30MB
effective_cache_size = 352MB
wal_buffers = 8MB
default_statistics_target = 50
constraint_exclusion = on
checkpoint_completion_target = 0.9
checkpoint_segments = 16
max_connections = 80

-Stefan

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