Can primary keys and foreign keys be used in versioned geodatabases?Geographic Information Systems
When should you not use foreign keys?
Reasons not to use Foreign Keys:
- you are making the DB work extra on every CRUD operation because it has to check FK consistency.
- by enforcing relationships, FKs specify an order in which you have to add/delete things, which can lead to refusal by the DB to do what you want.
What can be stored in a geodatabase?
The geodatabase supports all the different types of GIS data that can be used by ArcGIS, such as attribute data, geographic features, satellite and aerial images (raster data), CAD data, surface modeling or 3D data, utility and transportation network systems, GPS coordinates, and survey measurements.
Should you have foreign keys in data warehouse?
The reason for using a foreign key constraint in a data warehouse is the same as for any other database: to ensure data integrity. It is also possible that query performance will benefit because foreign keys permit certain types of query rewrite that are not normally possible without them.
Apr 22, 2010
Can foreign key reference composite primary key?
A referential constraint must have a one-to-one relationship between referencing and referenced columns. In other words, if the primary key is a set of columns (a composite key), then the foreign key also must be a set of columns that corresponds to the composite key.
Can a primary key be a foreign key at the same time?
The primary key column(s) can be used (along with the foreign key) to create a reference between two tables. As shown earlier, the primary key column of one table can be the foreign key column in another table. Thus, it creates a link between the two tables.
Sep 29, 2021
Can two tables have the same foreign key?
A declared foreign key (i.e., one enforced by the database engine) cannot tie to multiple other tables.
What is geodatabase versioning?
Versioning is the mechanism that enables concurrent multiuser geodatabase editing in ArcSDE geodatabases. It uses an optimistic concurrency data-locking model, which means no locks are applied to affected features and rows during long transactions.
What are the 3 main components of a geodatabase?
The geodatabase contains three primary dataset types:
- Feature classes.
- Raster datasets.
What are the three types of geodatabases?
There are three types:
- File geodatabases—Stored as folders in a file system.
- Personal geodatabases—All datasets are stored within a Microsoft Access data file, which is limited in size to 2 GB.
- Enterprise geodatabases—Also known as multiuser geodatabases, they can be unlimited in size and numbers of users.
What is wrong with foreign key?
A foreign key might point to data that no longer exists, or the foreign key’s data type doesn’t match the primary key data type, eroding referential integrity. Referential integrity can also be corrupted if the foreign key doesn’t reference all the data from the primary key.
Under what conditions must a foreign key not be null?
A foreign key may not be null when it is part of a composite primary key in the child table.
Jan 19, 2013
Do foreign keys hurt performance?
It’s a common mistake to avoid creating foreign keys in a database because they negatively impact the performance. It is true that foreign keys will impact INSERT, UPDATE and DELETE statements because they are data checking, but they improve the overall performance of a database.
Mar 18, 2020
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