Tagged Questions
3
votes
2answers
61 views
Performance of different precedence pseudocolumn solutions with LIMIT
I was wondering about the relative performance of the solutions provided in the answers to a question on stackoverflow, I decided to run some tests.
The OP wanted to get the first matching row given ...
4
votes
2answers
176 views
Performance on SQL Join
I have a query which takes ages to run mainly due to a join between 2 tables on a PK and FK.
The Key is prefixed with 2 letters (which is always the same, RN) followed by 7 digits
So RN1234567 for ...
8
votes
2answers
888 views
How (and why) does TOP impact an execution plan?
For a moderately complex query I am trying to optimize, I noticed that removing the TOP n clause changes the execution plan. I would have guessed that when a query includes TOP n the database engine ...
15
votes
2answers
504 views
T-SQL query using completely different plan depending on number of rows I'm updating
I have a SQL UPDATE statement with a "TOP (X)" clause, and the row I'm updating values in has about 4 billion rows. When I use "TOP (10)", I get one execution plan that executes almost instantly, but ...
2
votes
1answer
215 views
Query tuning - SQL Server
One of our developers are trying to run the below query on a development server, which involves pulling data from a linked server, production. The query ran for more than 14 hours before it was ...
