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Performance issue with Linked server in UAT environment, but same SQL when run from DEV server performs fine with the Linked server

Application:  Has linked servers to a SQL server and an Oracle server.

Recently a release was moved from DEV to UAT. A job which runs for 10mins in DEV is taking 90mins in UAT.

We isolated the problem to 2 SQL statements, but these statements run fine in DEV, which is also pointing to the same SQL linked server.

The JOB prior to release in UAT used to run in 10mins time. After the release the job is taking 90mins, but the same job runs in 10mins in DEV

Any pointers, I the problem SQL in the job has been identified to be SELECT statements from a VIEW, which in turn points to other views mapped out of the linked server(SQL).

But the same peice of code just runs fine in DEV??? puzzled.
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lakshmikatz
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lakshmikatz
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1 Solution
 
Mark WillsTopic AdvisorCommented:
There is a high probability that it is not the SQL code, but the environment around it...

Could be the drivers in UAT compared to DEV - make sure they are the same versions.

Could also be the configuration and networking for UAT compared to DEV.

Could be different security / virus settings where by UAT has very high scanning on all traffic (happended to me once - turned out the protection software was BYTE scanning in uat over the network because it was a different "trust" relationship between dev and production).

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Mark WillsTopic AdvisorCommented:
Also just heard of a production environment where the SAN was upgraded, and they "forgot" to turn caching back on ! Disaster for a few days (investigating everything SQL). There are a lot of environmental factors that can cause grief, trouble is, it tends to manifest itself in the SQL space and hence gets the blame.
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