A fix and a test case for Bug#26141 mixing table types in trigger

causes full table lock on innodb table.
Also fixes Bug#28502 Triggers that update another innodb table 
will block on X lock unnecessarily (duplciate).
Code review fixes.

Both bugs' synopses are misleading: InnoDB table is
not X locked. The statements, however, cannot proceed concurrently, 
but this happens due to lock conflicts for tables used in triggers,
not for the InnoDB table. 

If a user had an InnoDB table, and two triggers, AFTER UPDATE and 
AFTER INSERT, competing for different resources (e.g. two distinct
MyISAM tables), then these two triggers would not be able to execute
concurrently. Moreover, INSERTS/UPDATES of the InnoDB table would
not be able to run concurrently. 
The problem had other side-effects (see respective bug reports).

This behavior was a consequence of a shortcoming of the pre-locking
algorithm, which would not distinguish between different DML operations
(e.g. INSERT and DELETE) and pre-lock all the tables
that are used by any trigger defined on the subject table.

The idea of the fix is to extend the pre-locking algorithm to keep track,
for each table, what DML operation it is used for and not
load triggers that are known to never be fired.

1 files changed, 19 insertions, 0 deletions

diff --git a/sql/table.h b/sql/table.h
index b29ef8c6566..f8f7d7f06b7 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -59,6 +59,17 @@ enum tmp_table_type {NO_TMP_TABLE=0,
                      NON_TRANSACTIONAL_TMP_TABLE=1, TRANSACTIONAL_TMP_TABLE=2,
                      SYSTEM_TMP_TABLE=3};
 
+
+/** Event on which trigger is invoked. */
+enum trg_event_type
+{
+  TRG_EVENT_INSERT= 0,
+  TRG_EVENT_UPDATE= 1,
+  TRG_EVENT_DELETE= 2,
+  TRG_EVENT_MAX
+};
+
+
 enum frm_type_enum
 {
   FRMTYPE_ERROR= 0,
@@ -702,6 +713,13 @@ struct TABLE_LIST
   */
   bool          create;
 
+  /**
+    Indicates what triggers we need to pre-load for this TABLE_LIST
+    when opening an associated TABLE. This is filled after
+    the parsed tree is created.
+  */
+  uint8 trg_event_map;
+
   enum enum_schema_table_state schema_table_state;
   void calc_md5(char *buffer);
   void set_underlying_merge();
@@ -752,6 +770,7 @@ struct TABLE_LIST
   void reinit_before_use(THD *thd);
   Item_subselect *containing_subselect();
 
+  void set_trg_event_type(const st_lex *lex);
 private:
   bool prep_check_option(THD *thd, uint8 check_opt_type);
   bool prep_where(THD *thd, Item **conds, bool no_where_clause);