fix: ignore unique constraints in favor of indexes

Author: BuonOmo

lib/active_record/connection_adapters/cockroachdb/schema_statements.rb

@@ -222,36 +222,12 @@ def foreign_keys(table_name)
           end
         end
 
-        # OVERRIDE: Verify that the related attribute to the unique_constraint is not dropped.
-        #  See https://github.com/cockroachdb/activerecord-cockroachdb-adapter/issues/347.
+        # OVERRIDE: UNIQUE CONSTRAINTS will create indexes anyway, so we only consider
+        #   then as indexes.
+        # See https://github.com/cockroachdb/activerecord-cockroachdb-adapter/issues/347.
+        # See https://www.cockroachlabs.com/docs/stable/unique
         def unique_constraints(table_name)
-          scope = quoted_scope(table_name)
-
-          unique_info = internal_exec_query(<<~SQL, "SCHEMA", allow_retry: true, materialize_transactions: false)
-            SELECT c.conname, c.conrelid, c.conkey, c.condeferrable, c.condeferred
-            FROM pg_constraint c
-            JOIN pg_class t ON c.conrelid = t.oid
-            JOIN pg_namespace n ON n.oid = c.connamespace
-            JOIN pg_attribute a ON a.attrelid = c.conrelid AND a.attnum = c.conkey[1]    -- OVERRIDE
-            WHERE c.contype = 'u'
-              AND t.relname = #{scope[:name]}
-              AND n.nspname = #{scope[:schema]}
-              AND not a.attisdropped                                                     -- OVERRIDE
-          SQL
-
-          unique_info.map do |row|
-            conkey = row["conkey"].delete("{}").split(",").map(&:to_i)
-            columns = column_names_from_column_numbers(row["conrelid"], conkey)
-
-            deferrable = extract_constraint_deferrable(row["condeferrable"], row["condeferred"])
-
-            options = {
-              name: row["conname"],
-              deferrable: deferrable
-            }
-
-            UniqueConstraintDefinition.new(table_name, columns, options)
-          end
+          []
         end
 
         # CockroachDB uses unique_rowid() for primary keys, not sequences. It's

test/cases/schema_dumper_test.rb

@@ -35,11 +35,14 @@ def test_schema_dumps_unique_constraints
     end
 
     # See https://github.com/cockroachdb/activerecord-cockroachdb-adapter/issues/347
-    def test_dump_index_when_attisdropped_is_true
+    def test_dump_index_rather_than_unique_constraints
       ActiveRecord::Base.with_connection do |conn|
         conn.create_table :payments, force: true do |t|
           t.text "name"
-          t.index "lower(name::STRING) ASC", name: "lower_name_index_on_payments", unique: true
+          t.integer "value"
+          t.unique_constraint ["name", "value"], name: "as_unique_constraint"
+          t.index "lower(name::STRING) ASC", name: "simple_unique", unique: true
+          t.index "name", name: "unique_with_where", where: "name IS NOT NULL", unique: true
         end
       end
 
@@ -49,8 +52,11 @@ def test_dump_index_when_attisdropped_is_true
         dumper.send(:table, "payments", stream)
       end
       stream.rewind
-      index_line = stream.each_line.find { _1[/lower_name_index_on_payments/] }
-      assert_match /t\.index/, index_line
+      index_lines = stream.each_line.select { _1[/simple_unique|unique_with_where|as_unique_constraint/] }
+      assert_equal 3, index_lines.size
+      index_lines.each do |line|
+        assert_match /t.index/, line
+      end
     ensure
       ActiveRecord::Base.with_connection { _1.drop_table :payments, if_exists: true }
     end