From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mathias Kunter <mathiaskunter@gmail.com>
Cc: pgsql-docs@lists.postgresql.org
Subject: Re: random_page_cost configuration parameter
Date: Tue, 28 Dec 2021 11:03:25 -0500
Message-ID: <1760891.1640707405@sss.pgh.pa.us> (raw)
In-Reply-To: <9271c072-e91d-4dc5-c0a9-197f47291671@gmail.com>
References: <9271c072-e91d-4dc5-c0a9-197f47291671@gmail.com>
Mathias Kunter <mathiaskunter@gmail.com> writes:
> the documentation of the random_page_cost configuration parameter says:
>> Although the system will let you set random_page_cost to less than
>> seq_page_cost, it is not physically sensible to do so.
> However, I don't think this statement is true. 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.
regards, tom lane
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To: pgsql-docs@postgresql.org
Cc: tgl@sss.pgh.pa.us, mathiaskunter@gmail.com, pgsql-docs@lists.postgresql.org
Subject: Re: random_page_cost configuration parameter
In-Reply-To: <1760891.1640707405@sss.pgh.pa.us>
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