GIS - Geographic Information System Geodatabase Design and Management Questions and Answers — Questions and Answers
Question 1: A GIS administrator is designing a geodatabase for a utilities company to manage water distribution assets. To ensure data integrity, the design specifies that for any 'Water_Mains' feature, the 'Material' field (e.g., 'Ductile Iron', 'PVC') must dictate the valid range of values for the 'Diameter_Inches' field. For instance, PVC pipes are only available in diameters from 4 to 12 inches, while Ductile Iron is available from 6 to 36 inches. Which geodatabase mechanism is specifically designed to enforce this type of conditional attribute validation?
- Subtypes with associated range domains
- Contingent values (Correct answer)
- Relationship classes with rules
- Coded value domains
Correct answer: Contingent values
Contingent values are the correct mechanism because they are designed to constrain the valid values for one field based on the value of another. In this scenario, the valid values for 'Diameter_Inches' are contingent upon the value selected in the 'Material' field. While subtypes can have different domains assigned to them, contingent values provide a more direct and scalable solution for creating dependencies between fields without necessarily categorizing the entire feature class. Coded value domains only restrict a field to a list of values, and relationship classes manage associations between objects, not conditional validation within a single feature's attributes.
Question 2: An enterprise geodatabase is experiencing performance degradation during periods of heavy editing by multiple concurrent users. A consultant has been hired to recommend maintenance tasks. Which of the following is a critical, routine maintenance operation for an enterprise geodatabase that removes unreferenced states and moves entries from delta tables into the base tables to improve query performance?
- Rebuilding spatial indexes
- Shrinking the database files
- Compressing the geodatabase (Correct answer)
- Updating database statistics
Correct answer: Compressing the geodatabase
Compressing the geodatabase is the correct answer. The compress operation is essential for maintaining performance in a versioned enterprise geodatabase by removing unreferenced states and their associated delta table rows, and moving entries common to all versions into the base tables. This reduces the depth of the state tree that the database must search through for queries. While rebuilding indexes and updating statistics are also crucial maintenance tasks, they address different aspects of performance optimization (speeding up data retrieval and aiding the query optimizer, respectively). Shrinking the database is a file-level operation that reclaims space and is performed less frequently.
Question 3: A county's planning department maintains separate feature classes for 'Parcels' and 'Zoning'. To enforce data integrity, they need to implement a rule ensuring that every parcel polygon must be completely contained within a single zoning polygon. Which of the following geodatabase components and rules would be most appropriate to enforce this spatial relationship?
- A relationship class with 1:1 cardinality
- A subtype on the 'Parcels' feature class
- A geodatabase topology with a 'Must Be Covered By' rule (Correct answer)
- A range domain on the parcel area attribute
Correct answer: A geodatabase topology with a 'Must Be Covered By' rule
A geodatabase topology is the correct component for managing and enforcing spatial relationships between features. The 'Must Be Covered By' rule specifically ensures that features from one feature class (Parcels) are geometrically contained within the features of another feature class (Zoning). A relationship class links records based on attributes but doesn't enforce spatial containment. Subtypes categorize features within a single class, and domains restrict attribute values, neither of which can enforce this kind of spatial rule.
Question 4: Which of the following best differentiates geodatabase replication from versioning?
- Versioning is used for disconnected editing, while replication is for managing long transactions in a connected environment.
- Replication creates full copies of data in different geodatabases for synchronization, while versioning manages multiple states of data within a single geodatabase. (Correct answer)
- Versioning creates a parent-child relationship between geodatabases, while replication creates peer-to-peer connections.
- Replication is only used for file geodatabases, while versioning is exclusive to enterprise geodatabases.
Correct answer: Replication creates full copies of data in different geodatabases for synchronization, while versioning manages multiple states of data within a single geodatabase.
The primary distinction is that replication is designed to distribute and synchronize copies of data across multiple geodatabases, which might be in different geographic locations. In contrast, versioning is a mechanism within a single enterprise geodatabase that allows multiple users to edit data concurrently without applying locks or duplicating data, by managing different 'states' or versions of the data.
Question 5: When designing a geodatabase schema, a GIS analyst needs to categorize a 'Roads' feature class into 'Highway', 'Arterial', and 'Local' types. Each road type must have a different default value for the 'SpeedLimit' field and a different set of valid materials in the 'Pavement' field. What is the most efficient geodatabase design element to achieve this?
- Creating three separate feature classes, one for each road type.
- Using a coded value domain on a 'RoadType' text field.
- Implementing subtypes based on an integer 'RoadType' field. (Correct answer)
- Establishing a relationship class linking roads to a road types table.
Correct answer: Implementing subtypes based on an integer 'RoadType' field.
Subtypes are the most efficient method for categorizing features within a single feature class. They allow you to apply different default values and attribute domains to specific categories of features. In this case, subtypes for 'Highway', 'Arterial', and 'Local' can be created, and each subtype can be configured with its own default 'SpeedLimit' and its own assigned domain for the 'Pavement' field. This is more efficient than creating separate feature classes and provides more advanced behavior than a simple domain.
Question 6: A city manages its utility pole assets in a 'Poles' feature class and inspection records in a non-spatial 'Inspections' table. A key requirement is that if a utility pole is deleted from the geodatabase, all of its associated inspection records must also be automatically deleted. Which type of relationship class is required to enforce this behavior?
- Simple relationship class
- Many-to-many relationship class
- Attributed relationship class
- Composite relationship class (Correct answer)
Correct answer: Composite relationship class
A composite relationship class is designed for situations where the lifetime of the destination object (Inspections) is controlled by the lifetime of the origin object (Poles). A key behavior of composite relationships is the cascade delete; when the origin object is deleted, all related destination objects are automatically deleted. Simple relationship classes manage associations but do not have this life-cycle dependency behavior.
GIS - Geographic Information System Geodatabase Design and Management Questions and Answers
A GIS administrator is designing a geodatabase for a utilities company to manage water distribution assets.
To ensure data integrity, the design specifies that for any 'Water_Mains' feature, the 'Material' field (e.g., 'Ductile Iron', 'PVC') must dictate the valid range of values for the 'Diameter_Inches' field.
For instance, PVC pipes are only available in diameters from 4 to 12 inches, while Ductile Iron is available from 6 to 36 inches.
Which geodatabase mechanism is specifically designed to enforce this type of conditional attribute validation?