CDC and sys.dm_db_task_space_usage.internal_object_alloc_page

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CDC and sys.dm_db_task_space_usage.internal_object_alloc_page_count

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Shinoj Ramanathan

Posted Wednesday, October 24, 2012 4:33 PM

SSC Veteran

Group: General Forum Members
Last Login: Thursday, May 16, 2013 2:15 PM
Points: 220, Visits: 484

Gurus -

I have CDC setup (2008 R2) and the job is set to run continuous. The job calls the cdc scan procedure with default parameters
maxtran = 500
maxscans = 10
continuous = 5
pollinginterval = 5

Attached are the properties of the sys.dm_db_file_space_usage and sys.dm_db_task_space_usage and sys.dm_db_session_space_usage.

In "sys.dm_db_task_space_usage" the "internal_object_alloc_page_count" column increases gradually and the "internal_object_dealloc_page_count" doesnot change.

This intern means that the session uses space in the tempdb that gradually increases. It used to be in MB's now have moved to GB's.
But this doesnot add up to the output from sys.dm_db_file_space_usage (429840 in dm_db_task_space_usage is much higher that the sum of the four rows for internal_object_reserved_page_count column in sys.dm_db_file_space_usage) -Yes I have 4 tempdb's

Questions:-
1) Why is the dealloc not happening for the CDC job - (It deallocates for other processes that are continuously running like replication jobs in our system)
2) Why is the counts not making sense

Appreciate help understand!

Thanks