\"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil.\" (Donald Knuth). My SQL tables are unlikely to conta
Put indexes ONLY if you have to :)
There are times when putting indexes can actually hurt performance, depending on what the table is used for...
So, in other words, you would think about putting indexes on tables when it is necessary as determined by profiling the application.