Disable all table constraints in Oracle

sql

constraint-handling

plsql

database-performance

byAnton Shumikhin·Oct 18, 2024

Disable all non-foreign key constraints in Oracle using this efficient PL/SQL block:

BEGIN
   FOR c IN (SELECT constraint_name, table_name FROM user_constraints WHERE constraint_type != 'R') LOOP
      -- Let's remove those chains... freedom for our tables!
      EXECUTE IMMEDIATE 'ALTER TABLE '|| c.table_name ||' DISABLE CONSTRAINT '|| c.constraint_name;
   END LOOP;
END;

This script is focused on disabling check, unique, and primary key constraints across all tables in your schema.

The in-depth guide

Efficient constraint handling using PL/SQL blocks

Way better than temporary spool files, PL/SQL blocks help to manage constraints in a way that's productive and reliable. By immediately executing alteration commands inside a loop, we can achieve atomic operations, saving you some precious time.

Constraint selectivity

This isn't a one-size-fits-all solution. In the SELECT statement, we've specified WHERE constraint_type != 'R' to intentionally ignore foreign key constraints. Adjust the WHERE clause according to the constraint_type you want to disable.

Disabling constraints across multiple tables

Oracle's handy utility dbms_utility.exec_ddl_statement makes it easy to disable or enable constraints across multiple tables at once, leading to a wonderful boost in productivity.

Constraint enablement strategy

Primary key constraints first

Remember the golden rule when you're re-enabling constraints: primary key constraints go first, followed by the foreign keys. Doing so maintains the referential integrity and ensures all foreign keys have relevant primary keys to refer to.

Identifying constraints accurately

Navigating the data dictionary

By joining user_constraints with user_tables, we specifically target only those constraints that belong to tables. Hence, we are playing it safe by not messing up the constraints of views or materialized views.

Verifying the current constraint status

Perform a quick checkup on the current status (ENABLED or DISABLED) of constraints. This helps avoid unnecessary alterations and maintains control over the database state.

Scaled-up operations

Disabling on multiple levels

Your solution should be agile enough to accommodate various situations - disabling constraints for a single table, a list of tables, or all tables in your schema. Take the soccer ball and run with it!

Expert Tips and Safeguards

Dry-runs and testing

"A stitch in time saves nine." First, test the disabling effects in a non-production environment. Debugging potential issues here saves you real-world headaches.

Keep an eye on performance

Disabling constraints may impact the system load and performance. You wouldn't want a rioting user mob on your hands. So, consider off-peak hours for chunky operations.