diff --git a/lib/db/upgradelib.php b/lib/db/upgradelib.php
index 5103e0ba784..5247e49429e 100644
--- a/lib/db/upgradelib.php
+++ b/lib/db/upgradelib.php
@@ -30,6 +30,51 @@
 
 defined('MOODLE_INTERNAL') || die();
 
+/**
+ * Returns all non-view and non-temp tables with sane names.
+ * Prints list of non-supported tables using $OUTPUT->notification()
+ *
+ * @return array
+ */
+function upgrade_mysql_get_supported_tables() {
+    global $OUTPUT, $DB;
+
+    $tables = array();
+    $patprefix = str_replace('_', '\\_', $DB->get_prefix());
+    $pregprefix = preg_quote($DB->get_prefix(), '/');
+
+    $sql = "SHOW FULL TABLES LIKE '$patprefix%'";
+    $rs = $DB->get_recordset_sql($sql);
+    foreach ($rs as $record) {
+        $record = array_change_key_case((array)$record, CASE_LOWER);
+        $type = $record['table_type'];
+        unset($record['table_type']);
+        $fullname = array_shift($record);
+
+        if ($pregprefix === '') {
+            $name = $fullname;
+        } else {
+            $count = null;
+            $name = preg_replace("/^$pregprefix/", '', $fullname, -1, $count);
+            if ($count !== 1) {
+                continue;
+            }
+        }
+
+        if (!preg_match("/^[a-z][a-z0-9_]*$/", $name)) {
+            echo $OUTPUT->notification("Database table with invalid name '$fullname' detected, skipping.", 'notifyproblem');
+            continue;
+        }
+        if ($type === 'VIEW') {
+            echo $OUTPUT->notification("Unsupported database table view '$fullname' detected, skipping.", 'notifyproblem');
+            continue;
+        }
+        $tables[$name] = $name;
+    }
+    $rs->close();
+
+    return $tables;
+}
 
 /**
  * Remove all signed numbers from current database - mysql only.
@@ -50,7 +95,7 @@ function upgrade_mysql_fix_unsigned_columns() {
     $pbar = new progress_bar('mysqlconvertunsigned', 500, true);
 
     $prefix = $DB->get_prefix();
-    $tables = $DB->get_tables();
+    $tables = upgrade_mysql_get_supported_tables();
 
     $tablecount = count($tables);
     $i = 0;
@@ -115,7 +160,7 @@ function upgrade_mysql_fix_lob_columns() {
     $pbar = new progress_bar('mysqlconvertlobs', 500, true);
 
     $prefix = $DB->get_prefix();
-    $tables = $DB->get_tables();
+    $tables = upgrade_mysql_get_supported_tables();
     asort($tables);
 
     $tablecount = count($tables);