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In today’s world of Internet applications, more and more sites are offering features involving geography. For example, many sites will show you their stores, branches or franchises located on a map. “Yellow Pages” sites allow searches for all businesses, branches or individuals within a certain distance of a location. List fulfillment sites allow people to do mailings for all people within a certain distance of a location, such as the centroid of zip code.
To support these types of searches, Omnidex provides the capability to report and search based on distances from geographic coordinates. These searches are possible using some simple Omnidex indexes paired with a $DISTANCE function available in SQL SELECT statements. This function reports the distance between two sets of coordinates, and can also be used in criteria to select rows that meet distance requirements.
Current implementations of relational databases provide some support for distance calculations; however, these can be complex and costly. Some database requiring that the developer code trigonometric functions in stored procedures. Some databases do not use indexes to speed these searches. Some databases charge separately for this feature. Omnidex provides this capability in the base product.