doc

    Name:    blkpings.sql

    Author:  Mark Gurry

    The following query shows how many times each buffer has been pinged
    out of the buffer cache.

#

SELECT  df.tablespace_name, df.file_name, SUM(NVL(buf.xnc,0))    "PINGS"
  FROM  dba_data_files df, v$bh buf
  WHERE df.file_id = buf.file#
GROUP BY df.tablespace_name, df.file_name;