From e75fcdf3feaca7fac44dde23ea3059399c0ff384 Mon Sep 17 00:00:00 2001
From: Fumiaki MATSUSHIMA <mtsmfm@gmail.com>
Date: Sun, 13 Dec 2015 12:46:59 +0900
Subject: Use `SET CONSTRAINTS` for `disable_referential_integrity` without
 superuser privileges

ref: 72c1557254

- We must use `authors` fixture with `author_addresses` because of its foreign key constraint.
- Tests require PostgreSQL >= 9.4.2 because it had a bug about `ALTER CONSTRAINTS` and fixed in 9.4.2.
---
 .../postgresql/referential_integrity.rb            | 47 ++++++++++++++++++++--
 1 file changed, 43 insertions(+), 4 deletions(-)

(limited to 'activerecord/lib/active_record/connection_adapters/postgresql')

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb b/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb
index 44a7338bf5..730e7c7137 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb
@@ -6,8 +6,50 @@ module ActiveRecord
           true
         end
 
-        def disable_referential_integrity # :nodoc:
+        def disable_referential_integrity(&block) # :nodoc:
           if supports_disable_referential_integrity?
+            if supports_alter_constraint?
+              disable_referential_integrity_with_alter_constraint(&block)
+            else
+              disable_referential_integrity_with_disable_trigger(&block)
+            end
+          else
+            yield
+          end
+        end
+
+        private
+
+          def disable_referential_integrity_with_alter_constraint
+            tables_constraints = execute(<<-SQL).values
+              SELECT table_name, constraint_name
+              FROM information_schema.table_constraints
+              WHERE constraint_type = 'FOREIGN KEY'
+              AND is_deferrable = 'NO'
+            SQL
+
+            execute(
+              tables_constraints.collect { |table, constraint|
+                "ALTER TABLE #{quote_table_name(table)} ALTER CONSTRAINT #{constraint} DEFERRABLE"
+              }.join(";")
+            )
+
+            begin
+              transaction do
+                execute("SET CONSTRAINTS ALL DEFERRED")
+
+                yield
+              end
+            ensure
+              execute(
+                tables_constraints.collect { |table, constraint|
+                  "ALTER TABLE #{quote_table_name(table)} ALTER CONSTRAINT #{constraint} NOT DEFERRABLE"
+                }.join(";")
+              )
+            end
+          end
+
+          def disable_referential_integrity_with_disable_trigger
             original_exception = nil
 
             begin
@@ -39,10 +81,7 @@ Rails needs superuser privileges to disable referential integrity.
               end
             rescue ActiveRecord::ActiveRecordError
             end
-          else
-            yield
           end
-        end
       end
     end
   end
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