Scanning
[Storage Structures]

Collaboration diagram for Scanning:

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Detailed Description

Scans can be performed on B+tree and R-tree indexes and on files of records. Iterator classes scan_index_i, scan_rt_i and scan_file_i are used for Btree's, Rtree's and files, respectively.

Scans begin by creating an iterator to specify what to scan and the range of the scan.

An iterator's next() function is used to retrieve values from the scan (including the first). Next() will set the eof parameter to true only when no value can be retrieved for the current call, so if a file contains 2 records and next() has been called twice, eof will return false on the first and second calls, but true on the third.

The eof() function reports the value of eof returned from the last call to next(). This means you might find eof to be false, call next(), and get nothing back from next() (eof is now true).

The scan destructor frees and un-fixes (un-pins) all resources used by the scan.

Modules
	Scanning Files
	Scanning B+-Tree Indexes
	Scanning R-Tree Indexes

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