pgsql: doc: rewrite random_page_cost description

On Thu, Oct 30, 2025 at 11:12:20PM +0000, Bruce Momjian wrote:

doc: rewrite random_page_cost description

This removes some of the specifics of how the default was set, and adds
a mention of latency as a reason the value is lower than the storage
hardware might suggest. It still mentions caching.

Discussion: /messages/by-id/CAKAnmmK_nSPYr53LobUwQD59a-8U9GEC3XGJ43oaTYJq5nAOkw@mail.gmail.com

Backpatch-through: 13

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/3896e861b348f282813f165f60fb8ab3342114c6

Modified Files
--------------
doc/src/sgml/config.sgml | 36 ++++++++++++++++++------------------
1 file changed, 18 insertions(+), 18 deletions(-)

My apologies that I used the incorrect "Discussion" URL above. It
should have been:

/messages/by-id/80d8b470-50fe-40df-b692-3292dd015595@vondra.me

I had two random_page_cost threads in my mailbox and unfortunately used
the older one.

--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com

Do not let urgent matters crowd out time for investment in the future.