How to obtain actual file name of a FILESTREAM file.

Question

When a file is added to a FILESTREAM Blob field in SQL Server 2008 the file is renamed to something like 0000001c-0000019c-0004. Is there a way to retrieve this file name after a file is added?  I thought that [BLOB_Field].PathName() was promising
but this turns out to be some sort of virtual filepath that is only used when accessing the file through the filesystem and not via T-SQL. Any ideas?

Answer 1

Many Thanks to Kevin and Jacob, from your help I've been able to whip up a solution. It hasn't been throughly tested but seems to be what I'm looking for.
If you want to use this solution, you'll need to add the following Stored Procedures to your FILESTREAM database.
CREATE
PROCEDURE
[dbo].[procDBCC_PAGE]
@db_name varchar
(500),
@filenum INT
@pagenum INT
AS
BEGIN
SET
NOCOUNT
ON
DBCC
TRACEON (3604);
DBCC
PAGE (@db_name, @filenum, @pagenum, 3) WITH
TABLERESULTS;
SET
NOCOUNT
OFF
END
GO
CREATE
PROCEDURE
[dbo].[procFindLogSequenceNumber]
@TableName varchar
(500),
@FileLedgerID varchar
(500), --INT Causes error "Conversion failed when converting the varchar value '0x08166000' to data type int"
@LogSequenceNumber varchar
(500) OUTPUT
AS
SET
NOCOUNT
ON
DECLARE
@db_name varchar
(500)
DECLARE
@filenum INT
DECLARE
@pagenum INT
DECLARE
@parent_object varchar
(500)
SET
@db_name = db_name
CREATE
TABLE
#AllocationMetadata ([filenum] INT
, [pagenum] INT
INSERT
#AllocationMetadata ([filenum], [pagenum]) EXECUTE
sp_AllocationMetadata_FileNum_PageNum @TableName
--My Primary Key ID column is named FileLedgerID
SET
@filenum = (SELECT
TOP
1 [filenum] FROM
#AllocationMetadata)
SET
@pagenum = (SELECT
TOP
1 [pagenum] FROM
#AllocationMetadata)
CREATE
TABLE
#DBCC_PAGE_Output ([ParentObject] varchar
(MAX
), [Object] varchar
(MAX
), [Field] varchar
(MAX
), [VALUE] varchar
(MAX
INSERT
#DBCC_PAGE_Output ([ParentObject], [Object], [Field], [VALUE]) EXECUTE
procDBCC_PAGE @db_name, @filenum, @pagenum
SET
@parent_object = (SELECT
TOP
1 [ParentObject] FROM
#DBCC_PAGE_Output WHERE
[Field] = 'FileLedgerID'
AND
[VALUE] = @FileLedgerID)
--CreateLSN field Only
SET
@LogSequenceNumber = (SELECT
[VALUE] FROM
#DBCC_PAGE_Output WHERE
[ParentObject] = @parent_object AND
[Field] = 'CreateLSN'
DROP
TABLE
#AllocationMetadata
DROP
TABLE
#DBCC_PAGE_Output
SET
NOCOUNT
OFF
GO
You'll need to add the following Stored Procedure to your 'master' database. Don't forgo the
sys.sp_MS_marksystemobject step, as it won't work without it.
CREATE
PROCEDURE
[dbo].[sp_AllocationMetadata_FileNum_PageNum]
@object VARCHAR
(128) = NULL
AS
SELECT
CONVERT
(VARCHAR
(6),
CONVERT
(INT
, SUBSTRING
(sa.first_page, 6, 1) +
SUBSTRING
(sa.first_page, 5, 1))) AS
[filenum],
CONVERT
(VARCHAR
(20),
CONVERT
(INT
, SUBSTRING
(sa.first_page, 4, 1) +
SUBSTRING
(sa.first_page, 3, 1) +
SUBSTRING
(sa.first_page, 2, 1) +
SUBSTRING
(sa.first_page, 1, 1))) AS
[pagenum]
-- sp.object_id AS [Object_ID],
-- OBJECT_NAME (sp.object_id) AS [Object Name],
-- sp.index_id AS [Index ID],
-- sa.allocation_unit_id AS [Alloc Unit ID],
-- sa.type_desc AS [AllocUnitType],
-- '(' + CONVERT (VARCHAR (6),
-- CONVERT (INT, SUBSTRING (sa.first_page, 6, 1) +
-- SUBSTRING (sa.first_page, 5, 1))) +
-- ':' + CONVERT (VARCHAR (20),
-- CONVERT (INT, SUBSTRING (sa.first_page, 4, 1) +
-- SUBSTRING (sa.first_page, 3, 1) +
-- SUBSTRING (sa.first_page, 2, 1) +
-- SUBSTRING (sa.first_page, 1, 1))) +
-- ')' AS [First Page],
--sa.total_pages AS [Total Pages],
-- '(' + CONVERT (VARCHAR (6),
-- CONVERT (INT,
-- SUBSTRING (sa.root_page, 6, 1) +
-- SUBSTRING (sa.root_page, 5, 1))) +
-- ':' + CONVERT (VARCHAR (20),
-- CONVERT (INT,
-- SUBSTRING (sa.root_page, 4, 1) +
-- SUBSTRING (sa.root_page, 3, 1) +
-- SUBSTRING (sa.root_page, 2, 1) +
-- SUBSTRING (sa.root_page, 1, 1))) +
-- ')' AS [Root Page],
-- '(' + CONVERT (VARCHAR (6),
-- CONVERT (INT,
-- SUBSTRING (sa.first_iam_page, 6, 1) +
-- SUBSTRING (sa.first_iam_page, 5, 1))) +
-- ':' + CONVERT (VARCHAR (20),
-- CONVERT (INT,
-- SUBSTRING (sa.first_iam_page, 4, 1) +
-- SUBSTRING (sa.first_iam_page, 3, 1) +
-- SUBSTRING (sa.first_iam_page, 2, 1) +
-- SUBSTRING (sa.first_iam_page, 1, 1))) +
-- ')' AS [First IAM Page]
FROM
sys.system_internals_allocation_units AS
sa,
sys.partitions AS
sp
WHERE
sa.container_id = sp.partition_id
AND
sp.object_id =
(CASE
WHEN
(@object IS
NULL
THEN
sp.object_id
ELSE
OBJECT_ID
(@object)
END
AND
sa.type_desc = 'IN_ROW_DATA'
GO
EXEC
sys.sp_MS_marksystemobject sp_AllocationMetadata_FileNum_PageNum;
GO
And here's what I use in VBA to access the LogSequenceNumber.  FileLedgerID is the ID column of the data only table that stores the original filename, etc. This is also stored in the FILESTREAM table as a foreign key.
Public
Function
Test_procFindLogSequenceNumber(lngFileLedgerID as Long)
On
Error
GoTo
ErrorHandler
Dim
cmd As
New
ADODB.Command
Set
cnn_Public_FILESTREAM = Nothing
If
cnn_Public_FILESTREAM Is
Nothing
Then
Call
funOpenOrRefreshADOSQLConnection_FILESTREAM
cmd.ActiveConnection = cnn_Public_FILESTREAM 'This is my ADO connection to the FILESTREAM database, you'll have to do your own.
cmd.CommandText = "procFindLogSequenceNumber"
cmd.CommandType = adCmdStoredProc
cmd.Parameters.Append cmd.CreateParameter("@TableName"
, adLongVarChar, adParamInput, 500, "tblFileLedger_FILESTREAM"
cmd.Parameters.Append cmd.CreateParameter("@FileLedgerID"
, adInteger, adParamInput, , lngFileLedgerID)
cmd.Parameters.Append cmd.CreateParameter("@LogSequenceNumber"
, adVarWChar, adParamOutput, 500)
cmd.Execute , , adExecuteNoRecords
Debug.Print cmd.Parameters("@LogSequenceNumber"
ExitProcedure:
Set
cmd = Nothing
Exit
Function
ErrorHandler:
MsgBox Err.Description
Resume
ExitProcedure
End
Function
And here's what I use to convert the LSN into the exact File name.
Private
Function
funFileNameFromFile_LSN(strBLOB_File_LSN_fun As
String
) As
String
On
Error
GoTo
ErrorHandler
Dim
intPositionOfFirstSpace
'eg. 00000068:000008b0:0003 (104:2224:3)
'Replace colons with dashes
strBLOB_File_LSN_fun = Replace(strBLOB_File_LSN_fun, ":"
'Get position of first space character
intPositionOfFirstSpace = InStr(strBLOB_File_LSN_fun, " "
'Contract string to characters before the first space
funFileNameFromFile_LSN = Left(strBLOB_File_LSN_fun, intPositionOfFirstSpace - 1)
ExitProcedure:
Exit
Function
ErrorHandler:
MsgBox Err.Description
Resume
ExitProcedure
End
Function
I'm very grateful for the advice given here, but I think there still might be a legitimate reason to store the new file name that is created by SQL Server 2008. For instance, your MDF file might become corrupted beyond repair AND you have no backup. Stranger
things have happened. In this case, you would still have your important files available on the server (named like 00000068-000008b0-0003) but you'd be unable to salvage them. You could use trial and error, I suppose (ie. Try adding .doc to the file names and
see what works), but this would be unworkable as soon as you've got files in their hundreds.
Maybe this is just paranoia. Nevertheless I hope this can be of assistance to others.
Thanks again Kevin and Jacob.