Question : performance - NC Vc C index

Provided Clustered Index is designed right (incremental value), then there will not be any downside with Clustered index.

then, often, is NC index the bulk of performance factor for the database and app? For example, rarely does the queries just going to use the clustered index, but most likely a bunch of columns, for which a NC is required.

In other words, after a proper, one C index is setup, you never have to worry/deal about performance with the C index, but rather with the bunch of NC indexes that will or already have been created...?

thanks

Answer : performance - NC Vc C index

Well, remember that in some cases you will not have an incremental value in the clustered key, and sometimes there are multiple columns in the clustered key.  So you will have at some point fragmentation in the clustered index and that can cause performance problems.

Remember that you will probably never have covering indexes (NC) on all your queries unless your app is really simple, but having the right clustered index key and also having the right NC indexes, performance can be very good.  You will always have to maintain your indexes as you insert, update and delete rows in the tables.

Fragmentation and Statistics will be your performance problems and as long as you have a good strategy to watch and maintain the indexes and also detect unused indexes and remove them, you should be good on performance.  There is ALWAYS maintenance required on databases.