问题
I am using Sql Server 2000 and want to know why we can not create index on bit fields?
回答1:
Just a limitation of the product. SQL Server 2005+ does allow this.
Because of the Tipping Point a single column bit index is unlikely to be very useful unless the values are heavily skewed (a scenario for which filtered indexes in 2008 can help)
Still - could be useful as part of a composite covering index though.
回答2:
I would guess this is by design. A bit field can only have 1 of 2 values, so it would not be selective enough for an index to be useful.
来源：https://stackoverflow.com/questions/7607332/sql-server-index-on-bit-fields