Question

How would I go about finding the largest objects in a SQL Server database? First, by determining which tables (and related indices) are the largest and then determining which rows in a particular table are largest (we’re storing binary data in BLOBs)?

Are there any tools out there for helping with this kind of database analysis? Or are there some simple queries I could run against the system tables?

Answer 1

I’ve been using this SQL script (which I got from someone, somewhere – can’t reconstruct who it came from) for ages and it’s helped me quite a bit understanding and determining the size of indices and tables:

SELECT 
    t.name AS TableName,
    i.name as indexName,
    sum(p.rows) as RowCounts,
    sum(a.total_pages) as TotalPages, 
    sum(a.used_pages) as UsedPages, 
    sum(a.data_pages) as DataPages,
    (sum(a.total_pages) * 8) / 1024 as TotalSpaceMB, 
    (sum(a.used_pages) * 8) / 1024 as UsedSpaceMB, 
    (sum(a.data_pages) * 8) / 1024 as DataSpaceMB
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
WHERE 
    t.name NOT LIKE 'dt%' AND
    i.object_id > 255 AND  
    i.index_id <= 1
GROUP BY 
    t.name, i.object_id, i.index_id, i.name 
ORDER BY 
    object_name(i.object_id) 

Of course, you can use another ordering criteria, e.g.

ORDER BY SUM(p.rows) DESC

to get the tables with the most rows, or

ORDER BY SUM(a.total_pages) DESC

to get the tables with the most pages (8K blocks) used.