Fixed bug mdev-10884.mariadb-10.2.2

If a materialized derived table / view is specified by a unit
with SELECTs containing ORDER BY ... LIMIT then condition pushdown
cannot be done for these SELECTs.
If a materialized derived table / view is specified by a unit
containing global ORDER BY ... LIMIT then condition pushdown
cannot be done for this unit.

2 files changed, 16 insertions, 12 deletions

diff --git a/sql/sql_derived.cc b/sql/sql_derived.cc
index 85a85b9c3b2..0b67b952056 100644
--- a/sql/sql_derived.cc
+++ b/sql/sql_derived.cc
@@ -1131,27 +1131,31 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
   st_select_lex_unit *unit= derived->get_unit();
   st_select_lex *sl= unit->first_select();
 
+  /* Do not push conditions into constant derived */
+  if (unit->executed)
+    return false;
+
+  /* Do not push conditions into recursive with tables */
+  if (derived->is_recursive_with_table())
+    return false;
+
+  /* Do not push conditions into unit with global ORDER BY ... LIMIT */
+  if (unit->fake_select_lex && unit->fake_select_lex->explicit_limit)
+    return false;
+
   /* Check whether any select of 'unit' allows condition pushdown */
-  bool any_select_allows_cond_pushdown= false;
+  bool some_select_allows_cond_pushdown= false;
   for (; sl; sl= sl->next_select())
   {
     if (sl->cond_pushdown_is_allowed())
     {
-      any_select_allows_cond_pushdown= true;
+      some_select_allows_cond_pushdown= true;
       break;
     }
   }
-  if (!any_select_allows_cond_pushdown)
+  if (!some_select_allows_cond_pushdown)
     return false; 
 
-  /* Do not push conditions into constant derived */
-  if (unit->executed)
-    return false;
-
-  /* Do not push conditions into recursive with tables */
-  if (derived->is_recursive_with_table())
-    return false;
-
   /*
     Build the most restrictive condition extractable from 'cond'
     that can be pushed into the derived table 'derived'.
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index e499cc794a1..6387b6d1c2d 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -1160,7 +1160,7 @@ public:
   bool have_window_funcs() const { return (window_funcs.elements !=0); }
 
   bool cond_pushdown_is_allowed() const
-  { return !have_window_funcs() && !olap; }
+  { return !have_window_funcs() && !olap && !explicit_limit; }
   
 private:
   bool m_non_agg_field_used;