Part of the responsibility of a GIS professional is to understand the strengths and weaknesses of various spatial data structures. This week your readings are focused on spatial storage and indexing in spatial database applications. Next week we will add temporal data consideration for spatial databases in Week 10. This discussion intends to cover the two weeks’ subjects.
Objectives of this Assignment
• Explain examples of spatial indexes built using the spatial databases we have been using in this course.
• Understand how geodatabases do and do not make use of R-DBMSs spatial extensions
• Describe how versioning, one manifestation of time, is accomplished in geodatabases
• Discuss how temporal data can be stored in GIS
WHAT TO HAND IN
Deliver your answers to the questions below as per the instructions below into the Week 9 Discussion #4 submission link in Module 4: Spatial Data Optimization and Spatial Access.
1. (2 pts) Answer any two questions in 1-2 short paragraphs (100 words max per paragraph, 200 words max) and include one example with each of your answers, and include a reference (not included in word max), with a URL(s) as appropriate. Your examples and references should be different from any answers posted before yours for the same question, and different from the assigned readings. Besides the Week 9 and Week 10 readings, you might need to further study on your own to find answers, primarily in Esri Help.
a. Provide one example case study briefly describing how and why spatial indexes were built in a SQL Server database, OR in an Esri ArcGIS Pro geodatabase.
b. In MS SQL Server, compare and contrast the geometry data type and the geography data type. Which of these types is predominantly utilized by Esri ArcGIS Pro? Why? Provide one example.
c. Give an example of short- and long-transactions that might be ongoing concurrently on a spatial database in a land-management agency such as a county planning department. Why would long transactions interfere with short transactions and vice versa?
d. The Esri geodatabase approach to data versioning supports multi-user editing and long- transactions, which works for vector data; can raster data be versioned? If not, what is the reason for this limitation? What is the workaround for rasters? Provide one example.
e. Time stamps, or temporal data, can be stored in either separate fields or in separate tables in a spatial database. In what situation is a table with separate fields more appropriate for storing temporal data? In what situation should separate tables Not be recommended for storing temporal data in a database? Provide one example.
2. (1 pt) Comment at least 2 of your classmates’ posts. For example, you can post an additional link to a reference, answer a question they might have about the topic, post a comment on their interests based on your own experiences, etc. Please be sure to reply to classmates who have not yet received feedback, if possible. (100 words max per comment).
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