Method: Sequel::Schema::AlterTableGenerator#add_unique_constraint

Defined in:

lib/sequel/database/schema_generator.rb

#add_unique_constraint(columns, opts = OPTS) ⇒ Object

Add a unique constraint to the given column(s)

add_unique_constraint(:name) # ADD UNIQUE (name)
add_unique_constraint(:name, name: :unique_name) # ADD CONSTRAINT unique_name UNIQUE (name)

Supports the same :deferrable option as CreateTableGenerator#column.

PostgreSQL specific options:

:include

Include additional columns in the underlying index, to allow for index-only scans in more cases (PostgreSQL 11+).

:nulls_not_distinct

Use NULLS NOT DISTINCT to setup a constraint where NULL entries are considered distinct (PostgreSQL 15+)

:using_index

Use the USING INDEX clause to specify an existing unique index

:without_overlaps

Use WITHOUT OVERLAPS clause to specify an exclusion constraint on the final column (PostgreSQL 18+, composite unique constraints only).

# File 'lib/sequel/database/schema_generator.rb', line 493

def add_unique_constraint(columns, opts = OPTS)
  @operations << {:op => :add_constraint, :type => :unique, :columns => Array(columns)}.merge!(opts)
  nil
end