It was pointed out that pg_buffercache_summary()'s report of
the overall average usage count isn't that useful, and what
would be more helpful in many cases is to report totals for
each possible usage count. Add a new function to do it like
that. Since pg_buffercache 1.4 is already new for v16,
we don't need to create a new extension version; we'll just
define this as part of 1.4.
Nathan Bossart
Discussion: https://postgr.es/m/20230130233040.GA2800702@nathanxps13
Using pg_buffercache_summary() is significantly cheaper than querying
pg_buffercache and summarizing in SQL.
Author: Melih Mutlu <m.melihmutlu@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-by: Zhang Mingli <zmlpostgres@gmail.com>
Discussion: https://postgr.es/m/CAGPVpCQAXYo54Q%3D8gqBsS%3Du0uk9qhnnq4%2B710BtUhUisX1XGEg%40mail.gmail.com
We can't check the output of this view very closely without
creating portability headaches, but we can make sure that
the number of rows is as-expected. In any case, this is
sufficient to exercise all the C code within, which is a
lot better than the 0% coverage we had before.
DongWook Lee
Discussion: https://postgr.es/m/CAAcByaLCHGJB7qAENEcx9D09UL=w4ma+yijwF_-1MSqQZ9wK6Q@mail.gmail.com
Tom Lane
Andres Freund