Sql Server 2014. Simple table, as seen below...about 400 million rows
Non-clustered index on (last_name, first_name, dob, fk_client) INCLUDE (pk_member)
SELECT pk_member FROM tbl_member WHERE first_name = 'pat' AND last_name = 'xyz' AND dob = '11/1/82' AND fk_client = 5
Why would sql choose to ignore my index and instead scan the table on the clustered index on pk_member?
Also, the execution plan recommends this partial index instead: Index on (fk_client,dob) INCLUDE ([first_name],[last_name],[pk_member])
Thanks in advance.