Add UNIQUE constraints to internal schema

pkg/schema/schema.go

@@ -52,6 +52,9 @@ type Table struct {
 
 	// CheckConstraints is a map of all check constraints defined on the table
 	CheckConstraints map[string]CheckConstraint `json:"checkConstraints"`
+
+	// UniqueConstraints is a map of all unique constraints defined on the table
+	UniqueConstraints map[string]UniqueConstraint `json:"uniqueConstraints"`
 }
 
 type Column struct {
@@ -99,6 +102,14 @@ type CheckConstraint struct {
 	Definition string `json:"definition"`
 }
 
+type UniqueConstraint struct {
+	// Name is the name of the unique constraint in postgres
+	Name string `json:"name"`
+
+	// The columns that the unique constraint is defined on
+	Columns []string `json:"columns"`
+}
+
 func (s *Schema) GetTable(name string) *Table {
 	if s.Tables == nil {
 		return nil

pkg/state/state.go

@@ -190,6 +190,23 @@ BEGIN
 						AND cc_constraint.contype = 'c'
 						GROUP BY cc_constraint.oid
 					) AS cc_details
+        ),
+				'uniqueConstraints', (
+					SELECT json_object_agg(uc_details.conname, json_build_object(
+						'name', uc_details.conname,
+						'columns', uc_details.columns
+					))
+					FROM (
+						SELECT
+							uc_constraint.conname,
+							array_agg(uc_attr.attname ORDER BY uc_constraint.conkey::int[]) AS columns,
+							pg_get_constraintdef(uc_constraint.oid) AS definition
+						FROM pg_constraint AS uc_constraint
+						INNER JOIN pg_attribute uc_attr ON uc_attr.attrelid = uc_constraint.conrelid AND uc_attr.attnum = ANY(uc_constraint.conkey)
+						WHERE uc_constraint.conrelid = t.oid
+						AND uc_constraint.contype = 'u'
+						GROUP BY uc_constraint.oid
+					) AS uc_details
         ),
 				'foreignKeys', (
 					SELECT json_object_agg(fk_details.conname, json_build_object(