It is in the case if you just use just first in the predicate.
It will do scan if you use first columns of composite key and non-key column of composite key.
To trick it you can just dummy predicates like this and then non-key column:
[A,B] is your index, [C] - another column
To utilize index you write as:
SELECT A,B,C,D,E FROM test WHERE A=1 AND B=B AND C=3 ...why does it select the composite index by default, if the single A index is available?
It will use index only in the case if there are one or two predicates [A] Or [A],[B]. It will not use it in the order [B],[A] or [A],[C]. To be able to utilize index with additional column [C], you need to enforce index by ordering predicates as [A],[B] and [C].
