Hi
effective_cache_size is not cache. It is just approx value for query planner: how many data can be found in RAM (both
inshared_buffers and OS page cache)
> Q: Size of shared_buffers does not matter regarding keeping index in memory?
shared_buffers is cache for both tables and indexes pages. All data in tables and indexes are split to chunks 8 kb each
-pages (usually 8kb, it can be redefined during source compilation).
Shared buffers cache is fully automatic, active used pages keeps in memory, lower used pages may be evicted. You can
notpin any table or index to shared buffers.
regards, Sergei