相同的表，SQL 服务器查询中的不同表现

Question

We've been having problems with performance for a SQL Server at work. Queries that run well on one server run awfully on another (eg 20 minutes vs 16 hours, same box specs, seemingly same setup).

To try and understand the issue, I set up a update query (around 2m record table). When I tried to run it on a particular table, it could take anywhere up to 20 minutes to run. When I create a copy of that same table (ie select * into new table ) and run the same query on the copy it only takes 30 seconds.

For info, none of the tables have indexes on them.

I'm a bit limited in terms of what info I can share, but any ideas what could be causing an issue like this?

Answer 1

Creating just another table might not have all the indexes was created on the original table along with the data,or Query optimization configs might not be the same as the original table. DBAs will be able to help you why its talking this much time.