CSCI585CSCI585Introduction to Spatial Database Systemsby Cyrus ShahabiSpatial Databases: A Tour, Shashi Shekhar and Sanjay Chawla* Hart Hartmut Guting’s VLDB Journal v3, n4, October 1994CSCI585CSCI585Value of SDBMS• Traditional (non-spatial) database management systems provide:– Persistence across failures– Allows concurrent access to data– Scalability to search queries on very large datasets which do not fit inside main memories of computers– Efficient for non-spatial queries, but not for spatial queries• Non-spatial queries:– List the names of all bookstore with more than ten thousand titles.– List the names of ten customers, in terms of sales, in the year 2001• Spatial Queries:– List the names of all bookstores with ten miles of Minneapolis– List all customers who live in Tennessee and its adjoining statesCSCI585CSCI585Value of SDBMS – Spatial Data Examples • Examples of non-spatial data– Names, phone numbers, email addresses of people• Examples of Spatial data– Census Data– NASA satellites imagery - terabytes of data per day– Weather and Climate Data– Rivers, Farms, ecological impact– Medical ImagingCSCI585CSCI585Value of SDBMS – Users, Application Domains• Many important application domains have spatial data and queries. Some Examples follow:– Army Field Commander: Has there been any significant enemy troop movement since last night?– Insurance Risk Manager: Which homes are most likely to be affected in the next great flood on the Mississippi?– Medical Doctor: Based on this patient's MRI, have we treated somebody with a similar condition ?– Molecular Biologist:Is the topology of the amino acid biosynthesis gene in the genome found in any other sequence feature map in the database ?– Astronomer:Find all blue galaxies within 2 arcmin of quasars.CSCI585CSCI585Applications+• Various fields/applications require management of geometric, geographic or spatial data:– A geographic space: surface of the earth– Man-made space: layout of VLSI design– Model of rat brainCSCI585CSCI585What is a SDBMS ?• A SDBMS is a software module that– can work with an underlying DBMS– supports spatial data models, spatial abstract data types (ADTs) and a query language from which these ADTs are callable– supports spatial indexing, efficient algorithms for processing spatial operations, and domain specific rules for query optimization• Example: Oracle Spatial Extension– can work with Oracle 10g DBMS– Has spatial data types (e.g. polygon), operations (e.g. overlap) callable from SQL3 query language– Has spatial indices, e.g. R-treesCSCI585CSCI585What is an SDBMS?*• Common challenge: dealing with large collections of relatively simple geometric objects• Different from image and pictorialdatabase systems: – Containing sets of objects in space rather than images or pictures of a spaceCSCI585CSCI585SDBMS Example• Consider a spatial dataset with:– County boundary (dashed white line) – Census block - name, area, population, boundary (dark line)– Water bodies (dark polygons)– Satellite Imagery (gray scale pixels)• Storage in a SDBMS table:create table census_blocks (name string,area float,population number,boundary polygon );CSCI585CSCI585Modeling Spatial Data in Traditional DBMSx-axis(0,1)(0,0) (1,0)(1,1)1234ABCD1050y-axisCensus_blocksNameArea Population BoundaryPolyline((0,0),(0,1),(1,1),(1,0))1050 1 1839•A row in the table census_blocks•Question: Is Polyline datatype supported in DBMS?CSCI585CSCI585Spatial Data Types and Traditional Databases• Traditional relational DBMS– Support simple data types, e.g. number, strings, date– Modeling Spatial data types is tedious• Example: next slide shows modeling of polygon using numbers– Three new tables: polygon, edge, points• Note: Polygon is a polyline where last point and first point are same– A simple unit sqaure represented as 16 rows across 3 tables– Simple spatial operators, e.g. area(), require joining tables– Tedious and computationally inefficientCSCI585CSCI585Mapping “census_table” into a Relational Database y-coorx-coorPolygonedge-nameEdgeendpointPointendpoint1050105010501050ABCD1223344112340 10 01 01 1boundary-IDAABBCCDDedge-name105018391340AreaNameCensus_blocksPopulationboundary-IDCSCI585CSCI585Evolution of DBMS technologyObject-OrientedSystems (OODBMS)Network DBMS Hierarchical DBMSFile SystemsObject -RelationalORDBMSRelational DBMSCSCI585CSCI585Spatial Data Types and Post-relational Databases• Post-relational DBMS– Support user defined abstract data types– Spatial data types (e.g. polygon) can be added• Choice of post-relational DBMS– Object oriented (OO) DBMS– Object relational (OR) DBMS • A spatial database is a collection of spatial data types, operators, indices, processing strategies, etc. and can work with many post-relational DBMS as well as programming languages like Java, Visual Basic etc.CSCI585CSCI585How is a SDBMS different from a GIS ?• GIS is a software to visualize and analyze spatial data using spatial analysis functions such as– Search Thematic search, search by region, (re-)classification– Location analysis Buffer, corridor, overlay– Terrain analysis Slope/aspect, catchment, drainage network– Flow analysis Connectivity, shortest path– Distribution Change detection, proximity, nearest neighbor– Spatial analysis/Statistics Pattern, centrality, autocorrelation, indices of similarity, topology: hole description– Measurements Distance, perimeter, shape, adjacency, direction• GIS uses SDBMS – to store, search, query, share large spatial data setsCSCI585CSCI585How is a SDBMS different from a GIS ?• SDBMS focuses on– Efficient storage, querying, sharing of large spatial datasets– Provides simpler set based query operations – Example operations: search by region, overlay, nearest neighbor, distance, adjacency, perimeter etc.– Uses spatial indices and query optimization to speedup queries over large spatial datasets.• SDBMS may be used by applications other than GIS– Astronomy, Genomics, Multimedia information systems, ...• Will one use a GIS or a SDBM to answer the following:– How many neighboring countries does USA have?– Which country has highest number of neighbors?CSCI585CSCI585Three meanings of the acronym GIS• Geographic Information Services– Web-sites and service centers for casual users, e.g. travelers– Example: Service (e.g. AAA, mapquest)