PostgreSQL Project Leaders,
Currently, when a CHECK constraint is violated, PostgreSQL returns a generic
error message that includes the constraint name. While informative for
developers familiar with the database schema, this message can be less clear
for other team members, end-users, or in application logs. This lack of
specificity hinders the quick identification of the exact business rule that
has been violated and can lead to more time-consuming debugging and less
user-friendly error messages in applications.
Proposal:
I propose extending the syntax of the ALTER TABLE ADD CONSTRAINT statement (and
potentially CREATE TABLE) to allow for the specification of a custom error
message for each CHECK constraint. A possible syntax could be as follows:
ALTER TABLE table_name
ADD CONSTRAINT constraint_name
CHECK (condition)
MESSAGE 'Custom error message when the condition is not met.';
Benefits of Implementation:
Improved User Experience: Applications could capture and display more
contextual and helpful error messages to end-users, improving usability and
reducing confusion.
Enhanced Debugging: Developers could immediately identify the specific
business rule that has been violated, speeding up the debugging and resolution
of data integrity issues.
Implicit Documentation: The custom message would serve as a way to document
the intent of the constraint directly within the database schema, facilitating
understanding and maintenance of the data model.
Consistency: It would allow for a more consistent approach to providing
informative feedback on business rule violations, complementing the existing
capability in triggers.
Best regards,
