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What Is fn_virtualfilestats()
What Is fn_virtualfilestats() function view in SQL Server?
✍: FYIcenter.com
fn_virtualfilestats() is a Transact-SQL function view that returns I/O statistics for database files, including log files. In SQL Server, this information is also available from the sys.dm_io_virtual_file_stats dynamic management view.
fn_virtualfilestats() function has the following calling syntax:
fn_virtualfilestats ( { database_id | NULL } , { file_id | NULL } )
If you call it with NULL arguments, it will return I/O statistics for all files of all databases on this server.
fn_virtualfilestats() returns the following output fields on each data files:
Among all output fields, NumberReads, BytesRead, NumberWrites and BytesWritten are very useful to helpful for us to calculate the I/O performance.
For example, the following query returns I/O statistics of the first physical files in the current database:
select * from fn_virtualfilestats(DB_ID(), 1) DBID FILEID NUMBERREADS BYTESREAD NUMBERWRITES BYTESWRITTEN ... 6 1 3 114156 41344335872 1077341 39180853248 ...
⇒ Join sys.allocation_units with fn_virtualfilestats()
⇐ Find the File IDs of a Given Table
2019-06-29, 1746🔥, 0💬
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