A follow-up on this: Should documentation also mention that it does not make sense to set effective_cache_size < shared_buffers? And maybe it is worth prohibiting this or at least having a WARNING in logs?
Why: I see setups where with growing RAM and shared_buffers set to 25%, effective_cache_size remains untuned, at some point significantly below the value of shared_buffers. On Tue, Nov 6, 2018 at 21:42 Bruce Momjian <br...@momjian.us> wrote: > On Mon, Nov 5, 2018 at 02:01:12PM -0300, Alvaro Herrera wrote: > > On 2018-Nov-05, Bruce Momjian wrote: > > > > > Well, here are the lines in guc.c: > > > > > > gettext_noop("Sets the planner's assumption about the size > of the data cache."), > > > gettext_noop("That is, the size of the cache used for > PostgreSQL data files. " > > > "This is measured in disk pages, which are > normally 8 kB each."), > > > > I suggest "the size of data caches", plural, in the first line (two > > letters shorter, since I lost the article). And in the second line, use > > "... the size of the combined caches used for Pg data files, including > > both the kernel cache and shared buffers" -- a few words longer, which > > seems worth it to me. > > OK, I handled it slightly differently: > > > https://git.postgresql.org/pg/commitdiff/b43df566b372650a9b9e2a0dd9e695c1f16da14f > > I think "the size of" anything plural is confusing so I said "the total > size of". > > -- > Bruce Momjian <br...@momjian.us> http://momjian.us > EnterpriseDB http://enterprisedb.com > > + As you are, so once was I. As I am, so you will be. + > + Ancient Roman grave inscription + >