diff --git a/lib/database/mysqlschema.php b/lib/database/mysqlschema.php
index 105ef54512..9b710b2902 100644
--- a/lib/database/mysqlschema.php
+++ b/lib/database/mysqlschema.php
@@ -363,28 +363,6 @@ class MysqlSchema extends Schema
         return 'InnoDB';
     }
 
-    /**
-     * Get the unique index key name for a given column on this table
-     * @param $tableName
-     * @param $columnName
-     * @return string
-     */
-    public function _uniqueKey($tableName, $columnName)
-    {
-        return $this->_key($tableName, $columnName);
-    }
-
-    /**
-     * Get the index key name for a given column on this table
-     * @param $tableName
-     * @param $columnName
-     * @return string
-     */
-    public function _key($tableName, $columnName)
-    {
-        return "{$tableName}_{$columnName}_idx";
-    }
-
     /**
      * Append phrase(s) to an array of partial ALTER TABLE chunks in order
      * to alter the given column from its old state to a new one.
@@ -427,6 +405,11 @@ class MysqlSchema extends Schema
         $phrase[] = 'DROP INDEX ' . $keyName;
     }
 
+    public function appendAlterDropForeign(array &$phrase, $keyName)
+    {
+        $phrase[] = 'DROP FOREIGN KEY ' . $keyName;
+    }
+
     /**
      * Throw some table metadata onto the ALTER TABLE if we have a mismatch
      * in expected type, collation.
diff --git a/lib/database/pgsqlschema.php b/lib/database/pgsqlschema.php
index 046a3bd43d..38f7566eaf 100644
--- a/lib/database/pgsqlschema.php
+++ b/lib/database/pgsqlschema.php
@@ -371,6 +371,8 @@ class PgsqlSchema extends Schema
         foreach ($tableDef['fields'] as $name => &$col) {
             // No convenient support for field descriptions
             unset($col['description']);
+            // @fixme Nor for MariaDB-specific collations
+            unset($col['collate']);
 
             if ($col['type'] === 'serial') {
                 $col['type'] = 'int';
diff --git a/lib/database/schema.php b/lib/database/schema.php
index 05530db6f1..f472388bd7 100644
--- a/lib/database/schema.php
+++ b/lib/database/schema.php
@@ -764,10 +764,10 @@ class Schema
             $phrase[] = $prefix . ' DROP NOT NULL';
         }
 
-        if (!($old['default'] ?? false) && ($cd['default'] ?? false)) {
-            $phrase[] = $prefix . ' SET DEFAULT ' . $this->quoteDefaultValue($cd);
-        } elseif (($old['default'] ?? false) && !($cd['default'] ?? false)) {
+        if (!is_null($old['default'] ?? null) && is_null($cd['default'] ?? null)) {
             $phrase[] = $prefix . ' DROP DEFAULT';
+        } elseif (($old['default'] ?? null) !== ($cd['default'] ?? null)) {
+            $phrase[] = $prefix . ' SET DEFAULT ' . $this->quoteDefaultValue($cd);
         }
     }
 
@@ -819,7 +819,7 @@ class Schema
 
     public function appendAlterDropForeign(array &$phrase, $keyName)
     {
-        $phrase[] = 'DROP FOREIGN KEY ' . $keyName;
+        $phrase[] = 'DROP CONSTRAINT ' . $keyName;
     }
 
     public function appendAlterExtras(array &$phrase, $tableName, array $def)
@@ -1043,7 +1043,6 @@ class Schema
                     $col['type'] = 'datetime';
                     if (!array_key_exists('default', $col)) {
                         $col['default'] = 'CURRENT_TIMESTAMP';
-                        $col['auto_update_timestamp'] = true;
                     }
                     // no break
                 case 'datetime':