Can we create sparse index in Oracle or by default every index is a dense index (in Oracle).
Sparse index: In a sparse index, an index entry appears for only some of the
search-key values. Sparse indices can be used only if the relation is stored in
sorted order of the search key, that is, if the index is a clustering index. As
is true in dense indices, each index entry contains a search-key value and a
pointer to the first data record with that search-key value. To locate a record,
we find the index entry with the largest search-key value that is less than or
equal to the search-key value for which we are looking.We start at the record
pointed to by that index entry, and follow the pointers in the file untilwe find
the desired record.