self doubt about dense index

Question

In dense index the index is created for every search key value, does it mean for every record there will be an entry in the dense index? if yes then clustering index need not be dense because clustering index will be created for the clustered attribute which need not be unique and thus for two same values of the clustered attribute in the file there will be only one entry in clustered index and hence for every record there is not an entry in clustering index, thus it is non-dense. What is it?

Comments

For every record , there will be an index record.

Seconday key indexing is one such example.

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If it is so then the clustering index is non-dense

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Yes , clustering index is an example of non-dense index since only unique instances are present rather than all