What could cause this query to increase the execution time from 10 seconds to 2h30?
Without any changes in the database schema or the query, the execution time went from 10 seconds to about 2h30. The table has 1.04 million rows.
Additional info: if executing a "SELECT *" against this table, it executed in around 15 seconds; if executing a "SELECT ColX", the execution time went up to 1 minute.
Updated the statistics, rebuilt the clustered PK, but no changes in the performance were seen.
The query was improved, and this version is no longer in use, but I still would like to know what was the cause of this huge performance degradation.
The server is a SQL Server 2008R2.