Tomas Vondra <tomas@vondra.me> writes:
> On 2/11/25 21:18, Tom Lane wrote:
>> I think what we actually would like to know is how often we have to
>> close an open FD in order to make room to open a different file.
>> Maybe that's the same thing you mean by "cache miss", but it doesn't
>> seem like quite the right terminology. Anyway, +1 for adding some way
>> to discover how often that's happening.
> We can count the evictions (i.e. closing a file so that we can open a
> new one) too, but AFAICS that's about the same as counting "misses"
> (opening a file after not finding it in the cache). After the cache
> warms up, those counts should be about the same, I think.
Umm ... only if the set of files you want access to is quite static,
which doesn't seem like a great bet in the presence of temporary
tables and such. I think if we don't explicitly count evictions
then we'll be presenting misleading results.
regards, tom lane
