README.md in pg_ha_migrations-1.1.0 vs README.md in pg_ha_migrations-1.2.0

@@ -125,11 +125,17 @@
 #### safe\_change\_column\_default
 
 Safely change the default value for a column.
 
 ```ruby
+# Constant value:
 safe_change_column_default :table, :column, "value"
+safe_change_column_default :table, :column, DateTime.new(...)
+# Functional expression evaluated at row insert time:
+safe_change_column_default :table, :column, -> { "NOW()" }
+# Functional expression evaluated at migration time:
+safe_change_column_default :table, :column, -> { "'NOW()'" }
 ```
 
 #### safe\_make\_column\_nullable
 
 Safely make the column nullable.
@@ -166,9 +172,40 @@
 
 ```ruby
 safe_remove_concurrent_index :table, :name => :index_name
 ```
 
+#### safe\_add\_unvalidated\_check\_constraint
+
+Safely add a `CHECK` constraint. The constraint will not be immediately validated on existing rows to avoid a full table scan while holding an exclusive lock. After adding the constraint, you'll need to use `safe_validate_check_constraint` to validate existing rows.
+
+```ruby
+safe_add_unvalidated_check_constraint :table, "column LIKE 'example%'", name: :constraint_table_on_column_like_example
+```
+
+#### safe\_validate\_check\_constraint
+
+Safely validate (without acquiring an exclusive lock) existing rows for a newly added but as-yet unvalidated `CHECK` constraint.
+
+```ruby
+safe_validate_check_constraint :table, name: :constraint_table_on_column_like_example
+```
+
+#### safe\_rename\_constraint
+
+Safely rename any (not just `CHECK`) constraint.
+
+```ruby
+safe_rename_constraint :table, from: :constraint_table_on_column_like_typo, to: :constraint_table_on_column_like_example
+```
+
+#### unsafe\_remove\_constraint
+
+Drop any (not just `CHECK`) constraint.
+
+```ruby
+unsafe_remove_constraint :table, name: :constraint_table_on_column_like_example
+```
 
 ### Utilities
 
 #### safely\_acquire\_lock\_for\_table