Merge branch '10.1' into 10.2mariadb-10.2.32

2 files changed, 12 insertions, 0 deletions

diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index f31c3f36aa8..45916220896 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -4445,10 +4445,19 @@ bool Lock_tables_prelocking_strategy::
 handle_table(THD *thd, Query_tables_list *prelocking_ctx,
              TABLE_LIST *table_list, bool *need_prelocking)
 {
+  TABLE_LIST **last= prelocking_ctx->query_tables_last;
+
   if (DML_prelocking_strategy::handle_table(thd, prelocking_ctx, table_list,
                                             need_prelocking))
     return TRUE;
 
+  /*
+    normally we don't need to open FK-prelocked tables for RESTRICT,
+    MDL is enough. But under LOCK TABLES we have to open everything
+  */
+  for (TABLE_LIST *tl= *last; tl; tl= tl->next_global)
+    tl->open_strategy= TABLE_LIST::OPEN_NORMAL;
+
   /* We rely on a caller to check that table is going to be changed. */
   DBUG_ASSERT(table_list->lock_type >= TL_WRITE_ALLOW_WRITE);
 
diff --git a/sql/table.h b/sql/table.h
index e0541ef3f2e..0cf0e4efe00 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -1818,6 +1818,9 @@ struct TABLE_LIST
     open_type= routine ? OT_TEMPORARY_OR_BASE : OT_BASE_ONLY;
     belong_to_view= belong_to_view_arg;
     trg_event_map= trg_event_map_arg;
+    /* MDL is enough for read-only FK checks, we don't need the table */
+    if (prelocking_placeholder == FK && lock_type < TL_WRITE_ALLOW_WRITE)
+      open_strategy= OPEN_STUB;
 
     **last_ptr= this;
     prev_global= *last_ptr;