If I have an index called idxT1_C1C2C3 on table T1 that is non-clustered non-unique non covering, has 3 colums C1, C2, C3 in same order,
and I run a query
SELECT <column list......, 50 columns...> FROM T1
WHERE C1 = 'value'
can such query be expected at all to still use the idxT1_C1C2C3 index? Or provide any benefits to the query at all ? Or should I definitely create a separate index idxT1_C1 ? (on C1 column only, no matter covering or not...).
Sorry for a too simple question...
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