I use postgresql for windows server 2012 R2.
I use select pg_prewarm('tablename','read','main'); to load data into the os cache.
How can I know the database used the data in the os cache when I use the sql, select * from tablename, to query.
explain(analyze true, buffers true) select * from tablename
This sql above just show that the data in the database cache are used by querying. Can not show the data in the os cache.
Because I am optimizing the query speed by loading data into the os cache.
but the speed of query is as the same as the speed before using pg_prewarm.
So I doubt the database do not use the data in the os cache when it is querying.
I want to pick up the speed of query by using os cache and database cache.