I hit an annoying issue today. I wanted to regain space after I dropped several columns in a table. When I run the famous query from StackOverflow:
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SELECT t.NAME AS TableName, s.Name AS SchemaName, p.rows AS RowCounts, SUM(a.total_pages) * 8 AS TotalSpaceKB, CAST(ROUND(((SUM(a.total_pages) * 8) / 1024.00 / 1024.00), 2) AS NUMERIC(36, 2)) AS TotalSpaceMB, SUM(a.used_pages) * 8 AS UsedSpaceKB, CAST(ROUND(((SUM(a.used_pages) * 8) / 1024.00/ 1024.00), 2) AS NUMERIC(36, 2)) AS UsedSpaceMB, (SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS UnusedSpaceKB, CAST(ROUND(((SUM(a.total_pages) - SUM(a.used_pages)) * 8) / 1024.00, 2) AS NUMERIC(36, 2)) AS UnusedSpaceMB FROM sys.tables t INNER JOIN sys.indexes i ON t.OBJECT_ID = i.object_id INNER JOIN sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id INNER JOIN sys.allocation_units a ON p.partition_id = a.container_id LEFT OUTER JOIN sys.schemas s ON t.schema_id = s.schema_id WHERE t.NAME NOT LIKE 'dt%' AND t.is_ms_shipped = 0 AND i.OBJECT_ID > 255 GROUP BY t.Name, s.Name, p.Rows ORDER BY t.Name |
I got a set of numbers which were the same before and after the removal has
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DBCC CLEANTABLE('YOUR_DB', 'SCHEMA.TABLE'); |
There is, however, a potential issue with this approach if you are working in an active database. The query seems to block any other queries.