Fixed the bug mdev-12838.

If the optimizer chose an execution plan where
a semi-join nest were materialized and the
result of materialization was scanned to access
other tables by ref access it could build a key
over columns of the tables from the nest that
were actually inaccessible.
The patch performs a proper check whether a key
that uses columns of the tables from a materialized
semi-join nest can be employed to access outer tables.

1 files changed, 8 insertions, 0 deletions

diff --git a/sql/sql_select.h b/sql/sql_select.h
index 0623672840e..1bc1e4c2b7a 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -540,6 +540,8 @@ typedef struct st_join_table {
             !(used_sjm_lookup_tables & ~emb_sj_nest->sj_inner_tables));
   }
 
+  bool keyuse_is_valid_for_access_in_chosen_plan(JOIN *join, KEYUSE *keyuse);
+
 } JOIN_TAB;
 
 
@@ -1003,6 +1005,11 @@ public:
     to materialize and access by lookups
   */
   table_map sjm_lookup_tables;
+  /** 
+    Bitmap of semijoin tables that the chosen plan decided
+    to materialize to scan the results of materialization
+  */
+  table_map sjm_scan_tables;
   /*
     Constant tables for which we have found a row (as opposed to those for
     which we didn't).
@@ -1331,6 +1338,7 @@ public:
     pre_sort_join_tab= NULL;
     emb_sjm_nest= NULL;
     sjm_lookup_tables= 0;
+    sjm_scan_tables= 0;
     /* 
       The following is needed because JOIN::cleanup(true) may be called for 
       joins for which JOIN::optimize was aborted with an error before a proper