Sql-server – Page Splits on an empty table

page-splitssql serversql-server-2005

I have a monitoring tool that alerted me to high page splits, 50% of new allocations. After some Google Fu, I found the following query to look and see:

SELECT IOS.index_id, 
       O.NAME                       AS OBJECT_NAME, 
       I.NAME                       AS INDEX_NAME, 
       IOS.leaf_allocation_count    AS PAGE_SPLIT_FOR_INDEX, 
       IOS.nonleaf_allocation_count PAGE_ALLOCATION_CAUSED_BY_PAGESPLIT 
FROM 
<db>.sys.Dm_db_index_operational_stats(Db_id(N'DB_NAME'), NULL, NULL, NULL) IOS
JOIN <db>.sys.indexes I 
  ON IOS.index_id = I.index_id 
     AND IOS.object_id = I.object_id 
JOIN <db>.sys.objects O 
  ON IOS.object_id = O.object_id 
WHERE  o.NAME NOT LIKE 'sys%' 
       AND i.NAME IS NOT NULL 
       AND IOS.leaf_allocation_count != 0 
       AND IOS.nonleaf_allocation_count != 0 
ORDER  BY IOS.leaf_allocation_count DESC

The results showed that one index in particular was high in page splits/allocations caused by page splits. This table is empty.

Forgive my ignorance but how can an empty table cause page splits? There are no inserts, updates or deletes of the table.

SQL Server 9.0.5057

Any thoughts or direction would be appreciated.

Best Answer

if DB_ID(N'DB_NAME') returns null you will get object_id's from all databases. Try running from the target database:

use db_name


SELECT IOS.index_id, 
       O.NAME                       AS OBJECT_NAME, 
       I.NAME                       AS INDEX_NAME, 
       IOS.leaf_allocation_count    AS PAGE_SPLIT_FOR_INDEX, 
       IOS.nonleaf_allocation_count PAGE_ALLOCATION_CAUSED_BY_PAGESPLIT 
FROM 
sys.dm_db_index_operational_stats(Db_id(), NULL, NULL, NULL) IOS
JOIN sys.indexes I 
  ON IOS.index_id = I.index_id 
     AND IOS.object_id = I.object_id 
JOIN sys.objects O 
  ON IOS.object_id = O.object_id 
WHERE  o.NAME NOT LIKE 'sys%' 
       AND i.NAME IS NOT NULL 
       AND IOS.leaf_allocation_count != 0 
       AND IOS.nonleaf_allocation_count != 0 
ORDER  BY IOS.leaf_allocation_count DESC
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