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Thursday, April 06, 2006 

Types of queries

Now after defining these data structure our database is ready to answer fundamental queries like:
  • Whole Match Queries: Given a collection of N objects O1,.., On and aquery object Q find data objects that are within distance delta from Q
  • Sub-pattern Match: Given a collection of N objects O1,.., On and a query(sub-) object Q and a tolerance delta identify the parts of the data objects that match the query Q.
  • K- Nearest Neighbor queries: Given a collection of N objects O1,.., On and a query object Q find the K most similar data objects to Q.
  • All pairs queries (or ”spatial joins”): Given a collection of N objects O1 ,.., On find all objects that are within distance delta from each other.
for solving such queries we first need to find a distance function between two objects and find one or more numerical feature-extraction functions (to provide a quick test). Then Use a SAM (e.g., R-tree) to store and retrieve k-d feature vectors. here is an example of queries in context to computer games which uses these data structures :
  • Visibility - What can I see?
  • Ray intersections - What did the player just shoot?
  • Collision detection - Did the player just hit a wall?
  • Proximity queries - Where is the nearest power-up?

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