Subject: Re: random_page_cost configuration parameter
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-docs@lists.postgresql.org
References: <9271c072-e91d-4dc5-c0a9-197f47291671@gmail.com>
 <1760891.1640707405@sss.pgh.pa.us>
From: Mathias Kunter <mathiaskunter@gmail.com>
Message-ID: <6bb6023b-fce3-801d-e799-8111cc317e35@gmail.com>
Date: Wed, 5 Jan 2022 19:27:55 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.14.0
MIME-Version: 1.0
In-Reply-To: <1760891.1640707405@sss.pgh.pa.us>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: de-AT
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/6bb6023b-fce3-801d-e799-8111cc317e35%40gmail.com>
Precedence: bulk

Am 28.12.21 um 17:03 schrieb Tom Lane:
> Mathias Kunter <mathiaskunter@gmail.com> writes:
>> Consider the situation
>> where the randomly fetched pages are mostly (or even entirely) cached in
>> RAM, but where the sequentially fetched pages must be mostly read from
>> disk. An example for such a scenario is a database system which uses
>> RAM-cached indices.
> 
> I think fooling with effective_cache_size is a better way to model
> that situation.

The default value of effective_cache_size is 4 GB.  Which value should 
be used instead on a system which only has 4 GB of total RAM, but still 
uses RAM-cached indices?

Thank you very much for the clarification!

Best regards
Mathias Kunter