RPred Class Reference

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this class defines RTree searching predicates More...

#include <src/rtbasic.h>

Public Members


Detailed Description

this class defines RTree searching predicates.

This class is used to construct search predicates for RTree.

It consists of an "operator" (op), and a window (rectangle) that

is to be compared with the entries in the index.

An entry "e" in the RTree index satisfies the predicate if the

expression (const_key OP e) evaluates to be true.

The supported types of operators are:

EQUALS: for exact match (based on MBRs)

OVERLAPS: true if the window overlaps with the entry

The two types of queries below are not very useful for RTrees

but are provided anyway; but the result may not be correct.

CONTAINS: return entries that contains the window

WITHIN: return entries that are within the window

Note that the entries in the RTree use the minimum bounding

rectangle as the abstraction of real spatial objects. As such

the results returned by a search should be further examined to see

if the predicate holds true with the real representation of the

object. In some literature, this further examination is called

"refinement", while the procedure of searching the RTree is called

the "filtering" step.


Op op[public]

the operator to be performed on candidate records

RKey window[public]

querying window


Documentation generated by lqian@lqian-sun on Wed Jul 14 09:36:10 EDT 1999
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