October 22, 2009 at 9:22 am
I have query which runs for 1.36min on a database A of 1.6TB but the same query runs for 7 hrs on a database B of 600GB.
How do i troubleshoot to improve performance on database B, I am sure its nothing to do with query tuning as the same query runs faster on larger database.
PS : Both databases are 100% identical with respect to layout,indexes etc.
October 22, 2009 at 12:31 pm
are the stats up to date? indexes fragmented.?do the queries return the same amount of data?
check to see if the query plans are the same on the two databases.
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October 22, 2009 at 1:12 pm
What about hardware differences? CPU/Memory/Disk Layout? What about usage? Number of users/requests per server?
October 22, 2009 at 1:29 pm
1) compare the execution plans ! (and statistics)
2) is the hardware configration the same ?
( cpu , ram, disk , io chanels,..)
3) are these both dedicated sqlserver servers ?
4) other userdatabases ?
5) number of parallel users ?
Johan
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October 23, 2009 at 6:42 am
I agree with what everyone else has said, and, I wouldn't discount query tuning. It might be working OK with the set of data in one database and poorly with the set of data in another, but the problem doesn't have to be statistics, or index fragmentation. It can be the code.
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