Which table is blocking a shrinkfile operation

furthest-allocation.sql

/*
This script returns the further-allocated page per index per file in the database
This may be useful in reclaiming diskspace after a major data purge or migration operation

If a shrinkfile operation is not proceeding in a timely fashion or is being blocked,
this will help you target specific indexes to be rebuilt or migrated to a different filegroup
to help the space reclamation proceed.
*/


DECLARE
	  @tablename SYSNAME = NULL --Replace this if you only want to analyze a single table
	, @indexname SYSNAME = NULL --Replace this if you only want to analyze a single index of a single table
	, @result_limit INT = 200
;

-------------------------------------

DECLARE @tableid INT;
DECLARE @indexid INT;

SET @tableid = OBJECT_ID(@tablename)
SET @indexid = (
	SELECT i.index_id
	FROM sys.indexes i
	WHERE
		i.object_id = @tableid
		AND (
			i.name = @indexname
			OR (@indexname = '(Heap)' AND i.name IS NULL)
		)
)


SELECT
	TOP (@result_limit)
	  s.name AS [Schema]
	, COALESCE(t.name, '(System Table)') AS [Table]
	, COALESCE(i.name, '(Heap)') AS [Index]
	, df.name AS [File]
	, MAX(pg.allocated_page_page_id) AS [PageID]
	, MAX(pg.allocated_page_page_id) / 125 AS [Offset(MB)]
FROM sys.dm_db_database_page_allocations (DB_ID(), @tableid, @indexid, NULL, NULL) pg
	--INNER JOIN sys.partitions p
	--	ON pg.partition_id = p.partition_number
	--	AND pg.index_id = p.index_id
	--	AND pg.object_id = p.object_id
	INNER JOIN sys.indexes i
		ON pg.index_id = i.index_id
		AND pg.object_id = i.object_id
	LEFT JOIN sys.tables t
		ON pg.object_id = t.object_id
	LEFT JOIN sys.schemas s
		ON t.schema_id = s.schema_id
	INNER JOIN sys.database_files df
		ON pg.allocated_page_file_id = df.file_id
GROUP BY
	s.name, t.name, i.name, df.name
ORDER BY
	--pg.allocated_page_file_id ASC, pg.allocated_page_page_id DESC
	[File] ASC, [Offset(MB)] DESC