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Introduction to Spatial Database 2003-07-26 김동오 건국대학교 데이타베이스연구실
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Content Overview Who can benefit from spatial data menagement? GIS and SDBMS Three classes of users for spatial database A Stroll Through Spatial Databases Summary
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Overview 공간 데이타나 공간 질의를 다루기 위한 데 이타베이스의 필요
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Who can benefit from spatial data menagement? Mobile phone user Where is the nearest gas station? Is there a pet-food vendor on my way home? Army field commander Has there been any significant enemy troop movement since last night? Emergency service Where is the person calling for help located? Where is the best route to reach her? ...
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GIS and SDBMS SDBMS SDBMS are designed to handle very large amounts of spatial data stored on secondary devices, using specialized indices and query- processing techniques SDBMS provides simpler operations on a set of objects and sets of layers GIS Geographic Information System(GIS) is the principal technology motivating interest in Spatial Database Management Systems(SDBMSs) GIS provides a convenient mechanism for the analysis and visualization of geographic data GIS provides a rich set of operations over few objects and layers GIS can be built as the front-end of an SDBMS An efficient SDBMS can greatly increase the efficiency and productivity of a GIS
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Three classes of users for spatial database Specialized data management Analysis of spatial data GIS middleware - ESRI's Spatial Data Engine Spatial operation & Representing geographic information LBS - use GPS and mobile devices 1980s 1990s 2000s Time GISystems GIScience GIServices
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A Stroll Through Spatial Databases Space taxonomy and data models Query Language Query processing File organization and indices Query optimization Data mining
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Space taxonomy and data models Space taxonomy 공간을 구성 가능한 다중 서술 ex) 연산을 위한 다양한 공간 타입 ( Topological - Adjacent ), (Network - Shortest-path) ( Directional - North-of ), (Euclidean - Distance) Data model 공간에 관련된 객체를 표현하고 식별하기위한 규칙이나 규칙의 집합 ex) 서울시는 2 차원 평면, 1 차원 선, 무수히 많은 점들의 집합 또는 점으 로 표현 Object model 정형적인 공간 개체를 표현하는 이상적인 것 Conceptual model Map onto the computer using the Vector data structure Vector data structure Map region into polygon, line, point
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Query processing Query Single scan query Ex) Window query Multi scan query Ex) join Range query use filter-refine paradigm FILTER REFINE
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Query processing An algorithm to process the filter step of a spatial-join query Plane sweep technique Move a sweep line from left to right and stop at the first entry in R ∪ S. This rectangle is T. Search through the sorted rectangles of S until arriving at the first rectangle S f such that S f.xl > T.xu. Search S j in sorted rectangles of S for S j < S f. If (T.yl, T.yu) ∩ (S j.yl, S j.yu) is not null, then the S j intersects T. are part of the join result. Remove T from the set R ∪ S Move the sweep line across the set R ∪ S until it reaches the next rectangle entry. Now proceed as in step 2 and 3. Stop when the R ∪ S = Ø R4 S2 R1 S1 S3 R2 R3 sweep line ( T.xl, T.yl ) ( T.xu, T.yu ) R4S2S1R1S3R2R3
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File organization and indices Minimizing the sum of the compution and the I/O time Search in the index Sort and Order Row-ordered or Z-ordered B-tree R-tree CPU Main Memory CPU DISK 1234 5678 9101112 13141516 1256 3478 9101314 11121516
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Query optimization Join query Select before join or join before select ? "Find all senators who serve a district of area greater than sqare miles and who own a business within the district" A range query and a spatial join query "Name all senators who serve a district of area greater than 300 square miles" "Find all senators who own a business located in the district they serve"
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연산 횟수 Query optimization "Name all senators who serve a district of area greater than 300 square miles" "Find all senators who own a business located in the district they serve" spatial join query -> range query range query -> spatial join query namedistrict 김동오한국 이동진남해 손훈수대전 강홍구의정부 namebusinesslocation 김동오식당여수 손훈수식당서울 장유정미용실서울 namedistrict 김동오한국 손훈수대전 namebusinesslocation 김동오식당여수 손훈수식당대전 장유정미용실서울 namedistrict 김동오한국 이동진남해 손훈수대전 강홍구의정부 namedistrictbusinesslocation 김동오한국식당여수 4 + ( 2 * 3 ) *α = 10 ( 4 * 3 ) *α + 1 = 13
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Summary 공간 데이타 관리는 다양한 분야에서 사용 되며 과학적으로 중요한 역할을 담당한다. 도시 계획, 자연 자원 관리, 지구 기후 변화 측 정 등 사용자 별 공간 데이타 관리의 이점 Business user : 지리 정보를 활용한 마케팅, 점 포 분할 등 중요한 이차 정보로 활용 가능 Scientific user : 환경 및 자원 연구의 전문화 가 능 Personal user: 지역적 개인화가 가능
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