Merge branch 'mysql-5.6' into mysql-5.7

Author: Chaithra Gopalareddy

mysql-test/r/explain.result

@@ -749,3 +749,22 @@ ERROR 22007: Truncated incorrect INTEGER value: 'a'
 DROP TABLE t1;
 # End of test Bug#21139522
 End of 6.0 tests.
+#
+# Bug #18899860: EXPLAIN .. SELECT .. FOR UPDATE TAKES LOCKS
+#
+CREATE TABLE t1(c1 INT PRIMARY KEY) ENGINE=INNODB;
+INSERT INTO t1 VALUES (1),(2),(3);
+START TRANSACTION;
+EXPLAIN SELECT * FROM t1 WHERE c1 = 1 FOR UPDATE;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	NULL	const	PRIMARY	PRIMARY	4	const	1	100.00	Using index
+Warnings:
+Note	1003	/* select#1 */ select '1' AS `c1` from `test`.`t1` where 1
+START TRANSACTION;
+EXPLAIN SELECT * FROM t1 WHERE c1 = 1 FOR UPDATE;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	NULL	const	PRIMARY	PRIMARY	4	const	1	100.00	Using index
+Warnings:
+Note	1003	/* select#1 */ select '1' AS `c1` from `test`.`t1` where 1
+DROP TABLE t1;
+# End of test for Bug#18899860

mysql-test/t/explain.test

@@ -426,3 +426,25 @@ DROP TABLE t1;
 
 --echo # End of test Bug#21139522
 --echo End of 6.0 tests.
+
+--echo #
+--echo # Bug #18899860: EXPLAIN .. SELECT .. FOR UPDATE TAKES LOCKS
+--echo #
+
+CREATE TABLE t1(c1 INT PRIMARY KEY) ENGINE=INNODB;
+INSERT INTO t1 VALUES (1),(2),(3);
+CONNECT (c1,localhost,root,,);
+CONNECT (c2,localhost,root,,);
+CONNECTION c1;
+START TRANSACTION;
+EXPLAIN SELECT * FROM t1 WHERE c1 = 1 FOR UPDATE;
+CONNECTION c2;
+START TRANSACTION;
+EXPLAIN SELECT * FROM t1 WHERE c1 = 1 FOR UPDATE;
+CONNECTION default;
+DISCONNECT c1;
+DISCONNECT c2;
+DROP TABLE t1;
+
+--echo # End of test for Bug#18899860
+

sql/parse_tree_nodes.h

@@ -683,7 +683,12 @@ class PT_table_expression : public Parse_tree_node
          opt_procedure_analyse->contextualize(pc)))
       return true;
 
-    if (opt_select_lock_type.is_set)
+    /*
+      @todo: explain should not affect how we construct the query data
+      structure. Instead, consider to let lock_tables() adjust lock
+      requests according to the explain flag.
+    */
+    if (opt_select_lock_type.is_set && !pc->thd->lex->is_explain())
     {
       pc->select->set_lock_for_tables(opt_select_lock_type.lock_type);
       pc->thd->lex->safe_to_cache_query=
@@ -2256,7 +2261,12 @@ class PT_select_part2 : public Parse_tree_node
     DBUG_ASSERT(opt_procedure_analyse_clause == NULL ||
                 (opt_into1 == NULL && opt_into2 == NULL));
 
-    if (opt_select_lock_type.is_set)
+    /*
+      @todo: explain should not affect how we construct the query data
+      structure. Instead, consider to let lock_tables() adjust lock
+      requests according to the explain flag.
+    */
+    if (opt_select_lock_type.is_set && !pc->thd->lex->is_explain())
     {
       pc->select->set_lock_for_tables(opt_select_lock_type.lock_type);
       pc->thd->lex->safe_to_cache_query=

sql/sql_lex.h

@@ -2997,7 +2997,7 @@ struct LEX: public Query_tables_list
     m_current_select= select;
   }
   /// @return true if this is an EXPLAIN statement
-  bool is_explain() const { return describe; }
+  bool is_explain() const { return (describe & DESCRIBE_NORMAL); }
   char *length,*dec,*change;
   LEX_STRING name;
   char *help_arg;