How Can I Modify PostgreSQL Columns Without Recreating Dependent Views?

Relaxing PostgreSQL Column Modifications in Views

PostgreSQL ensures data integrity by requiring views to be recreated whenever columns used in them are modified. However, this can be cumbersome when you wish to simply adjust columns without affecting views.

Permanent Solution: Using Unrestricted Data Types

To completely avoid this issue, employ data types like text or varchar / character varying without a length specifier. These types allow unrestricted data storage, eliminating the need for length changes that require view recreation.

Enforcing Maximum Length with a CHECK Constraint

If you require maximum length enforcement, consider using a CHECK constraint:

ALTER TABLE monkey ADD CONSTRAINT monkey_name_len CHECK (length(name) < 101);

This constraint can be modified or removed independently, without impacting views or forcing unnecessary data modifications in the underlying table.

Impact of View Implementation

Contrary to popular belief, views in PostgreSQL are not mere aliases but special tables with rules defining their content. These rules, enforced by ON SELECT statements, ensure that any changes to underlying objects may need to be reflected in dependent views.

Limitations of ALTER VIEW

ALTER VIEW can only modify auxiliary attributes of views, such as permissions or comments. To alter the underlying query, use CREATE OR REPLACE VIEW. However, this method is not suitable when changing data types of resulting columns.

Dropping and Recreating Views

In such cases, the preferred approach is to DROP the existing view and CREATE a new one. This preserves the underlying data but eliminates any custom attributes associated with the view.

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