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Registering in clustered tables shows more value than non-clustered tables?

I created a cluster, and two tables empand sepa cluster.

Now when I make a simple request ...

explain plan select * from emp_cluster join dep_cluster using (dno)

... the cost is 26.

I created two other tables in the heap ( emp_heapand dep_heap), and when I do ...

explain plan select * from emp_heap join dep_heap using (dno)

... the cost is only 15.

This is less than a cluster. I inserted 33,000 records in emp tables and 99 records in department tables. I know that in a connection cluster it behaves well, but in my case it is the opposite ...?

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Possible reasons:

  • Statistics are out of date
  • Cluster tables are fragmented or have a low fill factor

, .

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