Constraint Operations

Operation: addConstraint

pgm.addConstraint( tablename, constraint_name, expression )

IMPORTANT

Add a named column constraint - postgres docs

Alias: createConstraint

Arguments

Name	Type	Description
tablename	Name	Name of the table to alter
constraint_name	string	Name for the constraint
expression	string or object	Constraint expression (raw sql) or definition -- see constraint definition section

Constraint Definition

Option	Type	Description
check	string or array	SQL for a check constraint(s)
unique	Name or array of Names or array of arrays of Names	Names of unique columns
primaryKey	Name or array of Names	Names of primary columns
exclude	string	SQL for an exclude constraint
deferrable	boolean	Flag for deferrable table constraint
deferred	boolean	Flag for initially deferred deferrable table constraint
comment	string	Comment on a singular, named constraint
foreignKeys	object or array of objects	Foreign keys specification -- see foreign keys section

Foreign Keys

Option	Type	Description
columns	Name or array of Names	Names of columns
references	Name	Names of foreign table and column names
referencesConstraintName	string	Name of the created constraint (only necessary when creating multiple constraints)
referencesConstraintComment	string	Comment on the individual foreign key constraint
onDelete	string	Action to perform on delete
onUpdate	string	Action to perform on update
match	string	FULL or SIMPLE

Reverse Operation: dropConstraint

pgm.dropConstraint( tablename, constraint_name, options )

IMPORTANT

Drop a named column constraint - postgres docs

Arguments

Name	Type	Description
tablename	Name	Name of the table to alter
constraint_name	string	Name of the constraint
options	object	Check below for available options

Options

Option	Type	Description
ifExists	boolean	Adds IF EXISTS to DROP CONSTRAINT so a missing constraint does not error
ifTableExists	boolean	Adds IF EXISTS to ALTER TABLE so a missing table does not error
cascade	boolean	Drops also dependent objects

NOTE

ifExists only guards the constraint name (DROP CONSTRAINT IF EXISTS). ifTableExists guards the table (ALTER TABLE IF EXISTS) and can hide typos, schema mistakes, or migration-order issues. It is mainly useful for retry-safe non-transactional migrations.

Operation: renameConstraint

pgm.renameConstraint( tablename, old_constraint_name, new_constraint_name )

IMPORTANT

Rename a constraint - postgres docs

Reverse Operation: same operation in opposite direction

Arguments

Name	Type	Description
tablename	Name	Name of the table to alter
old_constraint_name	string	Current constraint name
new_constraint_name	string	New constraint name