For example:

```
Given columns A,B,C,D,

IX_A is an index on 'A'

IX_AB is a covering index on 'AB'

```

IX\_A can be safely removed, for it is redundant: IX\_AB will be used in its place.
I want to know if this generalizes:

If I have:

```
IX_AB
IX_ABC
IX_ABCD

```

and so forth,

Can the lesser indices still be safely removed?
That is, does IX\_ABC make IX\_AB redundant, and does IX\_ABCD make both IX\_AB and IX\_ABC redundant?