MicrosoftMicrosoftJoseph_Pilov A followup question regarding "parallel processing" and multiple session_id's in the DMV's... you stated "You may sometimes notice a single session repeating multiple times in a DMV output"
In what DMS's does that happen?
Then it's kind of hard to figure out the differences between two samples of any DMV's (for working out differences in incremental counters, you need some kind of "uniqueness" or a "logical" Primary Key)
So what can be used as a "unique" column set for those DMV's
If there is no "uniqueness" for session_id's that are using DOP (kind of "family_id", or dop_id)
And several records are returned from the DMV's (with the same session_id)
* are all counters the "same" (in other words: do the "worker" report it's counter-statistics like "logical_reads" to the "parent/owning" session_id
- if all extra/duplicate DOP-session_id has the same values... why are they presented?
* If the extra/duplicate DOP-session_id entries contains counter-statistics that are *individual* for each of the "workers"... Should I just "sum" all incremental counters...
I can't just get my head around how DOP "workers" are reported in the DMV's
Any good paper out there that discusses this?
Another question which is probably "off topic" for this thread is: when/what counters are updated in DMV's
* At the end of SQL statement execution
* or: in real time -- meaning that I can see how many logical reads (etc) the query/session/xxx has been done *right now* (so I can calculate counter per second while the SQL Statement is executing)
