Extending Microsoft Dynamics 365 for Operations Cookbook

More on indexes

Table indexes are a physical structure that are used to improve read performance, ensure uniqueness of records, and for ordering of data in the table. When records are inserted, updated, or deleted, the index is also updated. We must therefore be careful when adding indexes, as they can carry a performance hit when writing data back to the table.

A typical index is an ordered collection of keys and a bookmark reference to the actual data. Finding a record matching a given key involves going to the appropriate location in the index where that key is stored. Then, you will have to follow the pointer to the location of the actual data. This, of course, requires two Operations: an index seek and a lookup to get the actual data. ...