GIS Databases With focused on ArcSDE

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1 Linköpings universitet / IDA / Div. for human-centered systems GIS Databases With focused on ArcSDE Imad Abugessaisa [email protected] GIS and SDBMS Geographical data is spatial data whose underlying frame reference is the earth s surface. GIS provides a rich set of operations over few objects and layers, whereas an SDBMS provides simpler operations on a set of objects and set of layers. SDBMS are also designed to handle very large amounts of spatial data stored on secondary devices. Also it helps to allow multiple users to simultaneously access shared spatial data. GIS can be built as Front-end of SDBMS. 2 1

GIS provides a rich set of operations over few objects and layers, whereas an SDBMS provides simpler operations on a set of objects and set of layers.

2 Managing Spatial Data Two major trends have had a profound impact on GIS data management. Data volumes have expanded greatly and are continuing to increase dramatically. GIS enterprises are becoming increasingly distributed, that is, users at different (sometimes mobile) geographic locations want to use data stored at several different locations. 3 Geodatabase Describe an integrated collection of geographic information: Can store and retrieve virtually any type of spatially referenced data. Can manage large volumes of data with high performance in a multiuser environment. Manage all the basic geodata types, including simple feature vector data types (points, lines, and polygons), as well as more advanced features that use rules for defining relationships, topologies, and behaviors of features. Can model the world better than any other geographic database management environment. 4 2

3 Geodatabase Describe an integrated collection of geographic information: Can store and retrieve virtually any type of spatially referenced data.

3 File and Personal Geodatabases (1) F.G used by a single editor and many readers in a GIS project. They store folders in a file system and can be created with ArcView, ArcEditor, and ArcInfo levels of ArcGIS. There is no limit on geodatabase size. Each dataset is stored as a file that can scale up to 1 TB in size, but this limit can be extended to 256 TB if needed. Vector data in File geodatabases can be compressed into a read-only format. Long transactions and versioning are not supported. 5 File and Personal Geodatabases (2) Personal Geodatabases are designed for a single user working with smaller datasets. They are built on a Microsoft Access file generated by the Microsoft Jet Engine that is included with ArcView, ArcEditor, and ArcInfo levels of ArcGIS Desktop. They have a maximum size limit of 2 GB but begin to have performance degradation between 250 and 500 MB. 6 3

Each dataset is stored as a file that can scale up to 1 TB in size, but this limit can be extended to 256 TB if needed. Vector data in File geodatabases can be compressed into a read-only format.

4 Geodatabase Storage Format ESRI is introducing a file-based implementation of the geodatabase. File-Based Geodatabase At ArcGIS 9.2, the complete functionality of a personal geodatabase and its complete information model have been implemented on top of a file system. File-based geodatabases fully support vector; raster; terrain; annotation; and all other geodatabase data types, rules, and relationships without the performance and geodatabase size limitations. 7 Geodatabase XML The geodatabase defines a generic model for geographic information and is implemented as either: a collection of files in a file system or a collection of tables in a RDBMS. The benefit of this generic model is that the geodatabase and its contents are multipurpose, shareable, and standards based. Geodatabase XML represents ESRI's open mechanism for information exchange between geodatabases and other external systems. XML interchange of geospatial information to and from the geodatabase is greatly simplified using the geodatabase XML specification. 8 4

File-based geodatabases fully support vector; raster; terrain; annotation; and all other geodatabase data types, rules, and relationships without the performance and geodatabase size limitations.

5 Advantage of Geodatabase An RDBMS for spatial and attribute data 9 Geodatabase Archiving Preserve edit transactions. Determine objects to archive. Supports full Geodatabase data model. Register as versioned. Enable archiving. Edit data. 10 5

6 Geodatabase Replication (1) Allows you to distribute copies of data a cross two or more geodatabases. Databases can be edited independently, then synchronized as needed. Implement as part of business workflow, an example of that Maintain copies of data at different organizational levels. 11 Geodatabase Replication (2) 12 6

Databases can be edited independently, then synchronized as needed.

7 Geodatabase Application Logic While the RDBMS manages simple data types and table, ArcSDE technology enables communication between GIS clients and the RDBMS. Additional application logic is required to implement more complex object behavior and integrity constraints. For example, feature classes, feature datasets, raster catalogs, topologies, networks, terrains, and so forth, are all examples of advanced elements within the geodatabase that are used to implement and model GIS behavior on top of the simple spatial representations stored in an RDBMS. These examples of geodatabase application logic are implemented using a combination of advanced RDBMS functionality and ArcObjects. 13 Geodatabase in ArcGIS 9.2 New Geodatabase storage options. Microsoft SQL Server Express. File Geodatabase. Geodatabase archiving Geodatabase replication 14 7

For example, feature classes, feature datasets, raster catalogs, topologies, networks, terrains, and so forth, are all examples of advanced elements within the geodatabase that are used to implement

8 Other Applications Visualization Tool SQL Applications SQL Applications Queries OpenGIS Spatial Queries lat, long x, y Spatial Data 123 E. Third St. Spatial Extender Oracle Spatial Traditional Database 15 Oracle Spatial and IBM Extender Oracle Spatial Oracle Spatial, an option for Oracle Database 10g Enterprise Edition, includes advanced spatial capabilities to support GIS applications, location-based services, and enterprise spatial information systems. Oracle Spatial extends the core location features included in every Oracle database with Oracle Locator. IBM DB2 Spatial Extender Spatial information, in formats such as point, lines, and polygons, can be analyzed, generated, stored, accessed, and queried within IBM DB2. The combination of spatial data with other, more traditional type data, adds another layer of intelligence to the database. 16 8

capabilities to support GIS applications, location-based services, and enterprise spatial information systems.

9 Sharing geographical data There are three possible ways to share geographical data, 17 Requirments All data (spatial and attributes) need to be stored in the DBMS Image Raster Coverages Annotation CAD Shapefiles DBMS Open Middleware are need it to augment the range of data types to include spatial data managed in a traditional RDBMS 18 9

Raster Coverages Annotation CAD Shapefiles DBMS Open Middleware are need it to

10 ArcSDE Technology ArcSDE technology is an integrated part of ArcGIS Desktop and ArcGIS Server and a core element of any enterprise GIS solution. Its primary role is to act as the database access engine to spatial data, its associated attributes, and metadata stored within a relational database management system (RDBMS). ArcSDE technology serves as the gateway between GIS clients and an RDBMS. It enables users to easily store, access, and manage spatial data on the leading database platforms. It is an essential component for configuring and managing a scalable geodatabase. 19 ArcSDE Technology ArcSDE technology is critical for users who need to manage long transactions and versioned-based workflows such as Managing historical archives Distributed editing Federated replicas managed across many RDBMS architectures Support for multiuser editing environments The responsibility for defining the specific RDBMS schema used to represent geographic data and for application logic is retained in ArcGIS, which provides the behavior, integrity, and utility of the underlying records

ArcSDE technology serves as the gateway between GIS clients and an RDBMS. It enables users to easily store, access, and manage spatial data on the leading database platforms.

11 ArcSDE Architecture Client Application ArcSDE Client API ArcSDE Server DBMS Server 21 Cooperative C/S-Processing Search and Retrieve Client Intensive Geoprocessing Functions Questions Results SDE Server DBMS 22 11

C/S-Processing Search and Retrieve Client Intensive

12 ArcSDE Services ArcSDE provides a services that: Enhance data management performance. Extend the range of data types that can be stored in a RDBMS. Enable schema portability between RDBMS. Offer configuration flexibility. 23 Supports Vector and Raster All data sets have spatial refrence Records geographic properties. Vector data Stored in ArcSDE feature class ( layer ). Raster data Stored in ArcSDE raster dataset

13 Vector Data in ArcSDE Stored as feature classes. Geodatabase container for vector data. Includes geometry and attributes. All geometry of the same type. Logically one table with spatial column 25 Raster Data in ArcSDE Geodatabase container for raster data Smallest unit of data is pixel. No discrete features ot attributes 26 13

14 Raster Tile Divide raster into tiles A set of pixels are tiled up. Each tile given a row and column number ( indexrd). Fast for zoom in operations. 27 Pyrmids Reduced resolution copies of original raster. Improves query performance Clients request data resolution to match display resolution. Number of pixels fetched is static as user zooms. Each level is tiled for storage in raster blocks 28 14

27 Pyrmids Reduced resolution copies of original raster.

15 29 ArcSDE Connections Applications server Performance considerations Decreases client load Decreases network load Increases server load Direct connect Performance considerations Increases clients load Increases network load Decreases server load 30 15

Increases server load Direct connect Performance

19 Refrence on the topic Spatial Databases: A Tour Authors: Shashi Shekhar and Sanjay Chawla Publisher: Prentice Hall, 2003 (ISBN ) 37 19

Chapter 1: Introduction to ArcGIS Server

Chapter 1: Introduction to ArcGIS Server At a high level you can think of ArcGIS Server as software that helps you take your geographic information and make it available to others. This data can be distributed