BUG#21726: Incorrect result with multiple invocations of LAST_INSERT_ID

Non-upper-level INSERTs (the ones in the body of stored procedure,
stored function, or trigger) into a table that have AUTO_INCREMENT
column didn't affected the result of LAST_INSERT_ID() on this level.

The problem was introduced with the fix of bug 6880, which in turn was
introduced with the fix of bug 3117, where current insert_id value was
remembered on the first call to LAST_INSERT_ID() (bug 3117) and was
returned from that function until it was reset before the next
_upper-level_ statement (bug 6880).

The fix for bug#21726 brings back the behaviour of version 4.0, and
implements the following: remember insert_id value at the beginning
of the statement or expression (which at that point equals to
the first insert_id value generated by the previous statement), and
return that remembered value from LAST_INSERT_ID() or @@LAST_INSERT_ID.

Thus, the value returned by LAST_INSERT_ID() is not affected by values
generated by current statement, nor by LAST_INSERT_ID(expr) calls in
this statement.

Version 5.1 does not have this bug (it was fixed by WL 3146).


mysql-test/r/rpl_insert_id.result:
  Add results for bug#21726: Incorrect result with multiple invocations
  of LAST_INSERT_ID, and bug#20339: stored procedure using LAST_INSERT_ID()
  does not replicate statement-based.
mysql-test/t/rpl_insert_id.test:
  Add test cases for bug#21726: Incorrect result with multiple invocations
  of LAST_INSERT_ID, and bug#20339: stored procedure using LAST_INSERT_ID()
  does not replicate statement-based.
sql/item_func.cc:
  Add implementation of Item_func_last_insert_id::fix_fields(), where we
  remember in THD::current_insert_id the first value generated during
  execution of the previous statement, which is returned then from
  Item_func_last_insert_id::val_int().
sql/item_func.h:
  Add declaration of Item_func_last_insert_id::fix_fields().
sql/log_event.cc:
  Do not set THD::last_insert_id_used on LAST_INSERT_ID_EVENT.  Though we
  know the statement will call LAST_INSERT_ID(), it wasn't called yet.
sql/set_var.cc:
  In sys_var_last_insert_id::value_ptr() remember in
  THD::current_insert_id the first value generated during execution of the
  previous statement, and return this value for @@LAST_INSERT_ID.
sql/sql_class.cc:
  Reset THD::last_insert_id_used after each statement execution.
sql/sql_class.h:
  Rather then remember current insert_id value on first invocation of
  THD::insert_id(), remember it in Item_func_last_insert_id::fix_fields(),
  sys_var_last_insert_id::value_ptr(), or mysql_execute_command().
  Remove THD::insert_id(), as it lost its value now.
sql/sql_insert.cc:
  THD::insert_id() is removed, use THD::last_insert_id directly.
sql/sql_load.cc:
  THD::insert_id() is removed, using THD::last_insert_id directly is OK.
sql/sql_parse.cc:
  Remember in THD::current_insert_id first generated insert id value of
  the previous statement in mysql_execute_command().
  No need to reset THD::last_insert_id_used in
  mysql_reset_thd_for_next_command(), it will be reset after each
  statement.
sql/sql_select.cc:
  If "IS NULL" is replaced with "= <LAST_INSERT_ID>", use right value,
  which is THD::current_insert_id, and also set THD::last_insert_id_used
  to issue binary log LAST_INSERT_ID_EVENT.
sql/sql_update.cc:
  THD::insert_id() is removed, use THD::last_insert_id directly.
tests/mysql_client_test.c:
  Add test case for bug#21726: Incorrect result with multiple invocations
  of LAST_INSERT_ID.

14 files changed, 405 insertions, 41 deletions

diff --git a/mysql-test/r/rpl_insert_id.result b/mysql-test/r/rpl_insert_id.result
index e425cce9508..d0360c8b9a3 100644
--- a/mysql-test/r/rpl_insert_id.result
+++ b/mysql-test/r/rpl_insert_id.result
@@ -234,6 +234,135 @@ n	b
 2	100
 3	350
 drop table t1;
+DROP PROCEDURE IF EXISTS p1;
+DROP TABLE IF EXISTS t1, t2;
+SELECT LAST_INSERT_ID(0);
+LAST_INSERT_ID(0)
+0
+CREATE TABLE t1 (
+id INT NOT NULL DEFAULT 0,
+last_id INT,
+PRIMARY KEY (id)
+);
+CREATE TABLE t2 (
+id INT NOT NULL AUTO_INCREMENT,
+last_id INT,
+PRIMARY KEY (id)
+);
+CREATE PROCEDURE p1()
+BEGIN
+INSERT INTO t2 (last_id) VALUES (LAST_INSERT_ID());
+INSERT INTO t1 (last_id) VALUES (LAST_INSERT_ID());
+END|
+CALL p1();
+SELECT * FROM t1;
+id	last_id
+0	1
+SELECT * FROM t2;
+id	last_id
+1	0
+SELECT * FROM t1;
+id	last_id
+0	1
+SELECT * FROM t2;
+id	last_id
+1	0
+DROP PROCEDURE p1;
+DROP TABLE t1, t2;
+DROP PROCEDURE IF EXISTS p1;
+DROP FUNCTION IF EXISTS f1;
+DROP FUNCTION IF EXISTS f2;
+DROP TABLE IF EXISTS t1, t2;
+CREATE TABLE t1 (
+i INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
+j INT DEFAULT 0
+);
+CREATE TABLE t2 (i INT);
+CREATE PROCEDURE p1()
+BEGIN
+INSERT INTO t1 (i) VALUES (NULL);
+INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+INSERT INTO t1 (i) VALUES (NULL), (NULL);
+INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+END |
+CREATE FUNCTION f1() RETURNS INT MODIFIES SQL DATA
+BEGIN
+INSERT INTO t1 (i) VALUES (NULL);
+INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+INSERT INTO t1 (i) VALUES (NULL), (NULL);
+INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+RETURN 0;
+END |
+CREATE FUNCTION f2() RETURNS INT NOT DETERMINISTIC
+RETURN LAST_INSERT_ID() |
+INSERT INTO t1 VALUES (NULL, -1);
+CALL p1();
+SELECT f1();
+f1()
+0
+INSERT INTO t1 VALUES (NULL, f2()), (NULL, LAST_INSERT_ID()),
+(NULL, LAST_INSERT_ID()), (NULL, f2()), (NULL, f2());
+INSERT INTO t1 VALUES (NULL, f2());
+INSERT INTO t1 VALUES (NULL, LAST_INSERT_ID()), (NULL, LAST_INSERT_ID(5)),
+(NULL, @@LAST_INSERT_ID);
+INSERT INTO t1 VALUES (NULL, 0), (NULL, LAST_INSERT_ID());
+UPDATE t1 SET j= -1 WHERE i IS NULL;
+SELECT * FROM t1;
+i	j
+1	-1
+2	0
+3	0
+4	0
+5	0
+6	0
+7	0
+8	3
+9	3
+10	3
+11	3
+12	3
+13	8
+14	13
+15	5
+16	13
+17	-1
+18	14
+SELECT * FROM t2;
+i
+2
+3
+5
+6
+SELECT * FROM t1;
+i	j
+1	-1
+2	0
+3	0
+4	0
+5	0
+6	0
+7	0
+8	3
+9	3
+10	3
+11	3
+12	3
+13	8
+14	13
+15	5
+16	13
+17	-1
+18	14
+SELECT * FROM t2;
+i
+2
+3
+5
+6
+DROP PROCEDURE p1;
+DROP FUNCTION f1;
+DROP FUNCTION f2;
+DROP TABLE t1, t2;
 
 # End of 5.0 tests
 
diff --git a/mysql-test/t/rpl_insert_id.test b/mysql-test/t/rpl_insert_id.test
index 3c46a5b4ca1..126aad68df4 100644
--- a/mysql-test/t/rpl_insert_id.test
+++ b/mysql-test/t/rpl_insert_id.test
@@ -244,6 +244,118 @@ select * from t1 order by n;
 
 connection master;
 drop table t1;
+
+#
+# BUG#20339: stored procedure using LAST_INSERT_ID() does not
+# replicate statement-based 
+#
+--disable_warnings
+DROP PROCEDURE IF EXISTS p1;
+DROP TABLE IF EXISTS t1, t2;
+--enable_warnings
+
+# Reset result of LAST_INSERT_ID().
+SELECT LAST_INSERT_ID(0);
+
+CREATE TABLE t1 (
+  id INT NOT NULL DEFAULT 0,
+  last_id INT,
+  PRIMARY KEY (id)
+);
+
+CREATE TABLE t2 (
+  id INT NOT NULL AUTO_INCREMENT,
+  last_id INT,
+  PRIMARY KEY (id)
+);
+
+delimiter |;
+CREATE PROCEDURE p1()
+BEGIN
+  INSERT INTO t2 (last_id) VALUES (LAST_INSERT_ID());
+  INSERT INTO t1 (last_id) VALUES (LAST_INSERT_ID());
+END|
+delimiter ;|
+
+CALL p1();
+SELECT * FROM t1;
+SELECT * FROM t2;
+
+sync_slave_with_master;
+SELECT * FROM t1;
+SELECT * FROM t2;
+
+connection master;
+
+DROP PROCEDURE p1;
+DROP TABLE t1, t2;
+
+
+#
+# BUG#21726: Incorrect result with multiple invocations of
+# LAST_INSERT_ID
+#
+--disable_warnings
+DROP PROCEDURE IF EXISTS p1;
+DROP FUNCTION IF EXISTS f1;
+DROP FUNCTION IF EXISTS f2;
+DROP TABLE IF EXISTS t1, t2;
+--enable_warnings
+
+CREATE TABLE t1 (
+    i INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
+    j INT DEFAULT 0
+);
+CREATE TABLE t2 (i INT);
+
+delimiter |;
+CREATE PROCEDURE p1()
+BEGIN
+  INSERT INTO t1 (i) VALUES (NULL);
+  INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+  INSERT INTO t1 (i) VALUES (NULL), (NULL);
+  INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+END |
+
+CREATE FUNCTION f1() RETURNS INT MODIFIES SQL DATA
+BEGIN
+  INSERT INTO t1 (i) VALUES (NULL);
+  INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+  INSERT INTO t1 (i) VALUES (NULL), (NULL);
+  INSERT INTO t2 (i) VALUES (LAST_INSERT_ID());
+  RETURN 0;
+END |
+
+CREATE FUNCTION f2() RETURNS INT NOT DETERMINISTIC
+  RETURN LAST_INSERT_ID() |
+delimiter ;|
+
+INSERT INTO t1 VALUES (NULL, -1);
+CALL p1();
+SELECT f1();
+INSERT INTO t1 VALUES (NULL, f2()), (NULL, LAST_INSERT_ID()),
+                      (NULL, LAST_INSERT_ID()), (NULL, f2()), (NULL, f2());
+INSERT INTO t1 VALUES (NULL, f2());
+INSERT INTO t1 VALUES (NULL, LAST_INSERT_ID()), (NULL, LAST_INSERT_ID(5)),
+                      (NULL, @@LAST_INSERT_ID);
+# Test replication of substitution "IS NULL" -> "= LAST_INSERT_ID".
+INSERT INTO t1 VALUES (NULL, 0), (NULL, LAST_INSERT_ID());
+UPDATE t1 SET j= -1 WHERE i IS NULL;
+
+SELECT * FROM t1;
+SELECT * FROM t2;
+
+sync_slave_with_master;
+SELECT * FROM t1;
+SELECT * FROM t2;
+
+connection master;
+DROP PROCEDURE p1;
+DROP FUNCTION f1;
+DROP FUNCTION f2;
+DROP TABLE t1, t2;
+
+
 sync_slave_with_master;
 
 --echo 
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 2e594c74031..e395a7a3af5 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -3345,6 +3345,34 @@ longlong Item_func_release_lock::val_int()
 }
 
 
+bool Item_func_last_insert_id::fix_fields(THD *thd, Item **ref)
+{
+  DBUG_ASSERT(fixed == 0);
+
+  if (Item_int_func::fix_fields(thd, ref))
+    return TRUE;
+
+  if (arg_count == 0)
+  {
+    if (!thd->last_insert_id_used)
+    {
+      /*
+        As this statement calls LAST_INSERT_ID(), set
+        THD::last_insert_id_used and remember first generated insert
+        id of the previous statement in THD::current_insert_id.
+      */
+      thd->last_insert_id_used= TRUE;
+      thd->current_insert_id= thd->last_insert_id;
+    }
+    null_value= FALSE;
+  }
+
+  thd->lex->uncacheable(UNCACHEABLE_SIDEEFFECT);
+
+  return FALSE;
+}
+
+
 longlong Item_func_last_insert_id::val_int()
 {
   THD *thd= current_thd;
@@ -3354,12 +3382,13 @@ longlong Item_func_last_insert_id::val_int()
     longlong value= args[0]->val_int();
     thd->insert_id(value);
     null_value= args[0]->null_value;
-    return value;                       // Avoid side effect of insert_id()
+    return value;
   }
-  thd->lex->uncacheable(UNCACHEABLE_SIDEEFFECT);
-  return thd->last_insert_id_used ? thd->current_insert_id : thd->insert_id();
+
+  return thd->current_insert_id;
 }
 
+
 /* This function is just used to test speed of different functions */
 
 longlong Item_func_benchmark::val_int()
diff --git a/sql/item_func.h b/sql/item_func.h
index 177daf0311f..31adc033034 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -891,6 +891,7 @@ public:
     if (arg_count)
       max_length= args[0]->max_length;
   }
+  bool fix_fields(THD *thd, Item **ref);
 };
 
 
diff --git a/sql/log_event.cc b/sql/log_event.cc
index 219434ab218..271658d8054 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -3365,7 +3365,6 @@ int Intvar_log_event::exec_event(struct st_relay_log_info* rli)
 {
   switch (type) {
   case LAST_INSERT_ID_EVENT:
-    thd->last_insert_id_used = 1;
     thd->last_insert_id = val;
     break;
   case INSERT_ID_EVENT:
diff --git a/sql/set_var.cc b/sql/set_var.cc
index c667e2f2bcc..d00857a2bc1 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -2571,8 +2571,17 @@ bool sys_var_last_insert_id::update(THD *thd, set_var *var)
 byte *sys_var_last_insert_id::value_ptr(THD *thd, enum_var_type type,
 					LEX_STRING *base)
 {
-  thd->sys_var_tmp.long_value= (long) thd->insert_id();
-  return (byte*) &thd->last_insert_id;
+  if (!thd->last_insert_id_used)
+  {
+    /*
+      As this statement reads @@LAST_INSERT_ID, set
+      THD::last_insert_id_used and remember first generated insert id
+      of the previous statement in THD::current_insert_id.
+    */
+    thd->last_insert_id_used= TRUE;
+    thd->current_insert_id= thd->last_insert_id;
+  }
+  return (byte*) &thd->current_insert_id;
 }
 
 
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 093173ab949..4d47ec338c0 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -553,10 +553,24 @@ bool THD::store_globals()
 }
 
 
-/* Cleanup after a query */
+/*
+  Cleanup after query.
+
+  SYNOPSIS
+    THD::cleanup_after_query()
 
+  DESCRIPTION
+    This function is used to reset thread data to it's default state.
+
+  NOTE
+    This function is not suitable for setting thread data to some
+    non-default values, as there is only one replication thread, so
+    different master threads may overwrite data of each other on
+    slave.
+*/
 void THD::cleanup_after_query()
 {
+  last_insert_id_used= FALSE;
   if (clear_next_insert_id)
   {
     clear_next_insert_id= 0;
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 039c133e885..ccc7a661446 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1252,17 +1252,29 @@ public:
   ulonglong  next_insert_id;
   /* Remember last next_insert_id to reset it if something went wrong */
   ulonglong  prev_insert_id;
+
   /*
-    The insert_id used for the last statement or set by SET LAST_INSERT_ID=#
-    or SELECT LAST_INSERT_ID(#).  Used for binary log and returned by
-    LAST_INSERT_ID()
+    At the beginning of the statement last_insert_id holds the first
+    generated value of the previous statement.  During statement
+    execution it is updated to the value just generated, but then
+    restored to the value that was generated first, so for the next
+    statement it will again be "the first generated value of the
+    previous statement".
+
+    It may also be set with "LAST_INSERT_ID(expr)" or
+    "@@LAST_INSERT_ID= expr", but the effect of such setting will be
+    seen only in the next statement.
   */
   ulonglong  last_insert_id;
+
   /*
-    Set to the first value that LAST_INSERT_ID() returned for the last
-    statement.  When this is set, last_insert_id_used is set to true.
+    current_insert_id remembers the first generated value of the
+    previous statement, and does not change during statement
+    execution.  Its value returned from LAST_INSERT_ID() and
+    @@LAST_INSERT_ID.
   */
   ulonglong  current_insert_id;
+
   ulonglong  limit_found_rows;
   ulonglong  options;           /* Bitmap of states */
   longlong   row_count_func;	/* For the ROW_COUNT() function */
@@ -1325,7 +1337,22 @@ public:
   bool       last_cuted_field;
   bool	     no_errors, password, is_fatal_error;
   bool	     query_start_used, rand_used, time_zone_used;
-  bool	     last_insert_id_used,insert_id_used, clear_next_insert_id;
+
+  /*
+    last_insert_id_used is set when current statement calls
+    LAST_INSERT_ID() or reads @@LAST_INSERT_ID, so that binary log
+    LAST_INSERT_ID_EVENT be generated.
+  */
+  bool	     last_insert_id_used;
+
+  /*
+    insert_id_used is set when current statement updates
+    THD::last_insert_id, so that binary log INSERT_ID_EVENT be
+    generated.
+  */
+  bool       insert_id_used;
+
+  bool       clear_next_insert_id;
   /* for IS NULL => = last_insert_id() fix in remove_eq_conds() */
   bool       substitute_null_with_insert_id;
   bool	     in_lock_tables;
@@ -1461,15 +1488,6 @@ public:
     insert_id_used=1;
     substitute_null_with_insert_id= TRUE;
   }
-  inline ulonglong insert_id(void)
-  {
-    if (!last_insert_id_used)
-    {
-      last_insert_id_used=1;
-      current_insert_id=last_insert_id;
-    }
-    return last_insert_id;
-  }
   inline ulonglong found_rows(void)
   {
     return limit_found_rows;
diff --git a/sql/sql_insert.cc b/sql/sql_insert.cc
index 3db6eae8695..43d646404f1 100644
--- a/sql/sql_insert.cc
+++ b/sql/sql_insert.cc
@@ -590,10 +590,8 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
 #endif
       error=write_record(thd, table ,&info);
     /*
-      If auto_increment values are used, save the first one
-       for LAST_INSERT_ID() and for the update log.
-       We can't use insert_id() as we don't want to touch the
-       last_insert_id_used flag.
+      If auto_increment values are used, save the first one for
+      LAST_INSERT_ID() and for the update log.
     */
     if (! id && thd->insert_id_used)
     {						// Get auto increment value
@@ -2447,7 +2445,7 @@ bool select_insert::send_data(List<Item> &values)
       */
       table->next_number_field->reset();
       if (!last_insert_id && thd->insert_id_used)
-        last_insert_id= thd->insert_id();
+        last_insert_id= thd->last_insert_id;
     }
   }
   DBUG_RETURN(error);
diff --git a/sql/sql_load.cc b/sql/sql_load.cc
index d5faf6ee7e9..bdc08b7bd2d 100644
--- a/sql/sql_load.cc
+++ b/sql/sql_load.cc
@@ -616,10 +616,8 @@ read_fixed_length(THD *thd, COPY_INFO &info, TABLE_LIST *table_list,
     thd->no_trans_update= no_trans_update;
    
     /*
-      If auto_increment values are used, save the first one
-       for LAST_INSERT_ID() and for the binary/update log.
-       We can't use insert_id() as we don't want to touch the
-       last_insert_id_used flag.
+      If auto_increment values are used, save the first one for
+      LAST_INSERT_ID() and for the binary/update log.
     */
     if (!id && thd->insert_id_used)
       id= thd->last_insert_id;
@@ -784,10 +782,8 @@ read_sep_field(THD *thd, COPY_INFO &info, TABLE_LIST *table_list,
     if (write_record(thd, table, &info))
       DBUG_RETURN(1);
     /*
-      If auto_increment values are used, save the first one
-       for LAST_INSERT_ID() and for the binary/update log.
-       We can't use insert_id() as we don't want to touch the
-       last_insert_id_used flag.
+      If auto_increment values are used, save the first one for
+      LAST_INSERT_ID() and for the binary/update log.
     */
     if (!id && thd->insert_id_used)
       id= thd->last_insert_id;
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 18d048df393..1b69e266442 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -2422,6 +2422,20 @@ mysql_execute_command(THD *thd)
   thd->net.no_send_error= 0;
 
   /*
+    Remember first generated insert id value of the previous
+    statement.  We remember it here at the beginning of the statement,
+    and also in Item_func_last_insert_id::fix_fields() and
+    sys_var_last_insert_id::value_ptr().  Last two places are required
+    because LAST_INSERT_ID() and @@LAST_INSERT_ID may also be used in
+    expression that is not executed with mysql_execute_command().
+
+    And we remember it here because some statements read
+    @@LAST_INSERT_ID indirectly, like "SELECT * FROM t1 WHERE id IS
+    NULL", that may replace "id IS NULL" with "id = <LAST_INSERT_ID>".
+  */
+  thd->current_insert_id= thd->last_insert_id;
+
+  /*
     In many cases first table of main SELECT_LEX have special meaning =>
     check that it is first table in global list and relink it first in 
     queries_tables list if it is necessary (we need such relinking only
@@ -5636,7 +5650,7 @@ void mysql_reset_thd_for_next_command(THD *thd)
   DBUG_ENTER("mysql_reset_thd_for_next_command");
   thd->free_list= 0;
   thd->select_number= 1;
-  thd->last_insert_id_used= thd->query_start_used= thd->insert_id_used=0;
+  thd->query_start_used= thd->insert_id_used=0;
   thd->is_fatal_error= thd->time_zone_used= 0;
   thd->server_status&= ~ (SERVER_MORE_RESULTS_EXISTS | 
                           SERVER_QUERY_NO_INDEX_USED |
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index b328d9162d5..87cbdef0522 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -8142,7 +8142,7 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
       Field *field=((Item_field*) args[0])->field;
       if (field->flags & AUTO_INCREMENT_FLAG && !field->table->maybe_null &&
 	  (thd->options & OPTION_AUTO_IS_NULL) &&
-	  thd->insert_id() && thd->substitute_null_with_insert_id)
+          thd->current_insert_id && thd->substitute_null_with_insert_id)
       {
 #ifdef HAVE_QUERY_CACHE
 	query_cache_abort(&thd->net);
@@ -8150,9 +8150,16 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
 	COND *new_cond;
 	if ((new_cond= new Item_func_eq(args[0],
 					new Item_int("last_insert_id()",
-						     thd->insert_id(),
+						     thd->current_insert_id,
 						     21))))
 	{
+          /*
+            Set THD::last_insert_id_used manually, as this statement
+            uses LAST_INSERT_ID() in a sense, and should issue
+            LAST_INSERT_ID_EVENT.
+          */
+          thd->last_insert_id_used= TRUE;
+
 	  cond=new_cond;
           /*
             Item_func_eq can't be fixed after creation so we do not check
diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index a5a767b6ebc..50914fd3408 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -568,7 +568,7 @@ int mysql_update(THD *thd,
     thd->row_count_func=
       (thd->client_capabilities & CLIENT_FOUND_ROWS) ? found : updated;
     send_ok(thd, (ulong) thd->row_count_func,
-	    thd->insert_id_used ? thd->insert_id() : 0L,buff);
+	    thd->insert_id_used ? thd->last_insert_id : 0L,buff);
     DBUG_PRINT("info",("%d records updated",updated));
   }
   thd->count_cuted_fields= CHECK_FIELD_IGNORE;		/* calc cuted fields */
@@ -1567,6 +1567,6 @@ bool multi_update::send_eof()
   thd->row_count_func=
     (thd->client_capabilities & CLIENT_FOUND_ROWS) ? found : updated;
   ::send_ok(thd, (ulong) thd->row_count_func,
-	    thd->insert_id_used ? thd->insert_id() : 0L,buff);
+	    thd->insert_id_used ? thd->last_insert_id : 0L,buff);
   return FALSE;
 }
diff --git a/tests/mysql_client_test.c b/tests/mysql_client_test.c
index 8a444590301..d3f39296445 100644
--- a/tests/mysql_client_test.c
+++ b/tests/mysql_client_test.c
@@ -15237,6 +15237,43 @@ static void test_bug21206()
   DBUG_VOID_RETURN;
 }
 
+/*
+  Bug#21726: Incorrect result with multiple invocations of
+  LAST_INSERT_ID
+
+  Test that client gets updated value of insert_id on UPDATE that uses
+  LAST_INSERT_ID(expr).
+*/
+static void test_bug21726()
+{
+  const char *create_table[]=
+  {
+    "DROP TABLE IF EXISTS t1",
+    "CREATE TABLE t1 (i INT)",
+    "INSERT INTO t1 VALUES (1)",
+  };
+  const char *update_query= "UPDATE t1 SET i= LAST_INSERT_ID(i + 1)";
+  int rc;
+  my_ulonglong insert_id;
+
+  DBUG_ENTER("test_bug21726");
+  myheader("test_bug21726");
+
+  fill_tables(create_table, sizeof(create_table) / sizeof(*create_table));
+
+  rc= mysql_query(mysql, update_query);
+  myquery(rc);
+  insert_id= mysql_insert_id(mysql);
+  DIE_UNLESS(insert_id == 2);
+
+  rc= mysql_query(mysql, update_query);
+  myquery(rc);
+  insert_id= mysql_insert_id(mysql);
+  DIE_UNLESS(insert_id == 3);
+
+  DBUG_VOID_RETURN;
+}
+
 
 /*
   Read and parse arguments and MySQL options from my.cnf
@@ -15511,7 +15548,8 @@ static struct my_tests_st my_tests[]= {
   { "test_bug17667", test_bug17667 },
   { "test_bug19671", test_bug19671 },
   { "test_bug15752", test_bug15752 },
-  { "test_bug21206", test_bug21206},
+  { "test_bug21206", test_bug21206 },
+  { "test_bug21726", test_bug21726 },
   { 0, 0 }
 };