MAGETWO-96908: [2.3] Wrong attribute value in flat table

Author: dhorytskyi

app/code/Magento/Catalog/Model/Indexer/Product/Flat/FlatTableBuilder.php

@@ -346,12 +346,20 @@ protected function _updateTemporaryTableByStoreValues(
                 }
 
                 //Update not simple attributes (eg. dropdown)
-                if (isset($flatColumns[$attributeCode . $valueFieldSuffix])) {
-                    $select = $this->_connection->select()->joinInner(
-                        ['t' => $this->_productIndexerHelper->getTable('eav_attribute_option_value')],
-                        't.option_id = et.' . $attributeCode . ' AND t.store_id=' . $storeId,
-                        [$attributeCode . $valueFieldSuffix => 't.value']
-                    );
+                $columnName = $attributeCode . $valueFieldSuffix;
+                if (isset($flatColumns[$columnName])) {
+                    $select = $this->_connection->select();
+                    $select->joinLeft(
+                        ['t0' => $this->_productIndexerHelper->getTable('eav_attribute_option_value')],
+                        't0.option_id = et.' . $attributeCode . ' AND t0.store_id = 0',
+                        []
+                    )->joinLeft(
+                        ['ts' => $this->_productIndexerHelper->getTable('eav_attribute_option_value')],
+                        'ts.option_id = et.' . $attributeCode . ' AND ts.store_id = ' . $storeId,
+                        []
+                    )->columns(
+                        [$columnName => $this->_connection->getIfNullSql('ts.value', 't0.value')]
+                    )->where($columnName . ' IS NOT NULL');
                     if (!empty($changedIds)) {
                         $select->where($this->_connection->quoteInto('et.entity_id IN (?)', $changedIds));
                     }