I have a customer who has upgraded their SQL Server from SQL Server 2005 to SQL Server 2012. According to them, no other changes were made. They have an ERP database which does a full reindex once a week (the SQL just locates every index in the DB and rebuilds it) and it completed normally in 3 hours before the upgrade.
The DB is 178GB. After the upgrade, suddenly performance tanked. They performed a reindex and it was taking several hours and before being half way finished the log file grew to close to 500 GB. They ran out of disk space, so they dumped the log and did the reindex in pieces.
Would an upgrade to SQL Server 2012 change how indexes need to be rebuilt? Did something about the upgrade change the indexes? Do upgrades like this change indexes? We are going to monitor this on the next go around and see if it drops back to 3 hours or if it takes a huge amount of time and space again. Any imaginative thoughts would be appreciated as well, since I'm getting a lot of this information second hand from my customer :)