When data scientist calculates average value for two observations.
When third-party vendor is trying to sell me his new tool for index defragmentation.
When dev system goes under maintenance and we start coding in notepad.
When using IBM predictive analytics product on Apple tablet.
When you ask DBA to restore a month old backup.
When failing to correctly configure resource governor in SQL Server.
When handling big data.
When adding query hint to your query.
When you scale out your data warehouse server.
When running same query on new server.