Is there a way to retrieve the total read/write operations initiated by a PG server. I'm looking for measuring the IOPS of a server over a period of time.
postgres itself doesn't actually know how many physical disk operations are taking place as it only deals with files.
if its unix/linux, you can use iostat or sar to track all the disk I/O over an interval of time.
Depending on your goal, you can use pg_stat_database to see blocks read and blocks read from buffer cache as well as block read time and block write time per database.