From a25c2c8249592c2e4964d98d32a0747329d3d112 Mon Sep 17 00:00:00 2001
From: Pieter Hoste <hoste.pieter@gmail.com>
Date: Thu, 25 Feb 2021 12:31:12 +0100
Subject: [PATCH] Restore UNIQUE_CHECKS mysql variable to its original value
 when done with changing the database structure. This prevents potentially
 inserting duplicated values while manipulating data in the setup:upgrade
 command.

---
 .../Framework/Setup/Declaration/Schema/OperationsExecutor.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/internal/Magento/Framework/Setup/Declaration/Schema/OperationsExecutor.php b/lib/internal/Magento/Framework/Setup/Declaration/Schema/OperationsExecutor.php
index ed1baff1d3323..9c3c5b8a5b15d 100644
--- a/lib/internal/Magento/Framework/Setup/Declaration/Schema/OperationsExecutor.php
+++ b/lib/internal/Magento/Framework/Setup/Declaration/Schema/OperationsExecutor.php
@@ -135,7 +135,7 @@ private function startSetupForAllConnections()
             $this->resourceConnection->getConnection($resource)
                 ->startSetup();
             $this->resourceConnection->getConnection($resource)
-                ->query('SET UNIQUE_CHECKS=0');
+                ->query('SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0');
         }
     }
 
@@ -150,6 +150,8 @@ private function endSetupForAllConnections()
         foreach ($this->sharding->getResources() as $resource) {
             $this->resourceConnection->getConnection($resource)
                 ->endSetup();
+            $this->resourceConnection->getConnection($resource)
+                ->query('SET UNIQUE_CHECKS=IF(@OLD_UNIQUE_CHECKS=0, 0, 1)');
         }
     }