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Iterators

An iterator provides access to all or some of the records in a heap or index.

We are going to model Iterator as an abstract class (to use C++ terminology).

I.e., Iterator specifies but does not implement (pure virtual) member functions:

• open: Prepare the iterator for retrieval of rows.

• next: Return the next orw, or NULL if there is none.

• close: Cleanup.

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