Merge bk-internal.mysql.com:/home/bk/mysql-5.1-runtime

into  damien-katzs-computer.local:/Users/dkatz/mysql-5.1-runtime

include/config-win.h

@@ -21,6 +21,9 @@
 /* We have to do this define before including windows.h to get the AWE API
 functions */
 #define _WIN32_WINNT     0x0500
+#else
+/* Get NT 4.0 functions */
+#define _WIN32_WINNT     0x0400
 #endif
 
 #if defined(_MSC_VER) && _MSC_VER >= 1400

include/my_pthread.h

@@ -101,6 +101,7 @@ struct timespec {
 
 void win_pthread_init(void);
 int win_pthread_setspecific(void *A,void *B,uint length);
+int win_pthread_mutex_trylock(pthread_mutex_t *mutex);
 int pthread_create(pthread_t *,pthread_attr_t *,pthread_handler,void *);
 int pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
 int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex);
@@ -156,7 +157,7 @@ void pthread_exit(void *a);	 /* was #define pthread_exit(A) ExitThread(A)*/
 #define pthread_equal(A,B) ((A) == (B))
 #define pthread_mutex_init(A,B)  (InitializeCriticalSection(A),0)
 #define pthread_mutex_lock(A)	 (EnterCriticalSection(A),0)
-#define pthread_mutex_trylock(A) (WaitForSingleObject((A), 0) == WAIT_TIMEOUT)
+#define pthread_mutex_trylock(A) win_pthread_mutex_trylock((A))
 #define pthread_mutex_unlock(A)  LeaveCriticalSection(A)
 #define pthread_mutex_destroy(A) DeleteCriticalSection(A)
 #define my_pthread_setprio(A,B)  SetThreadPriority(GetCurrentThread(), (B))
@@ -472,7 +473,7 @@ typedef struct st_safe_mutex_info_t
 
 int safe_mutex_init(safe_mutex_t *mp, const pthread_mutexattr_t *attr,
                     const char *file, uint line);
-int safe_mutex_lock(safe_mutex_t *mp,const char *file, uint line);
+int safe_mutex_lock(safe_mutex_t *mp, my_bool try_lock, const char *file, uint line);
 int safe_mutex_unlock(safe_mutex_t *mp,const char *file, uint line);
 int safe_mutex_destroy(safe_mutex_t *mp,const char *file, uint line);
 int safe_cond_wait(pthread_cond_t *cond, safe_mutex_t *mp,const char *file,
@@ -495,12 +496,12 @@ void safe_mutex_end(FILE *file);
 #undef pthread_cond_timedwait
 #undef pthread_mutex_trylock
 #define pthread_mutex_init(A,B) safe_mutex_init((A),(B),__FILE__,__LINE__)
-#define pthread_mutex_lock(A) safe_mutex_lock((A),__FILE__,__LINE__)
+#define pthread_mutex_lock(A) safe_mutex_lock((A), FALSE, __FILE__, __LINE__)
 #define pthread_mutex_unlock(A) safe_mutex_unlock((A),__FILE__,__LINE__)
 #define pthread_mutex_destroy(A) safe_mutex_destroy((A),__FILE__,__LINE__)
 #define pthread_cond_wait(A,B) safe_cond_wait((A),(B),__FILE__,__LINE__)
 #define pthread_cond_timedwait(A,B,C) safe_cond_timedwait((A),(B),(C),__FILE__,__LINE__)
-#define pthread_mutex_trylock(A) pthread_mutex_lock(A)
+#define pthread_mutex_trylock(A) safe_mutex_lock((A), TRUE, __FILE__, __LINE__)
 #define pthread_mutex_t safe_mutex_t
 #define safe_mutex_assert_owner(mp) \
           DBUG_ASSERT((mp)->count > 0 && \

libmysqld/lib_sql.cc

@@ -111,7 +111,7 @@ emb_advanced_command(MYSQL *mysql, enum enum_server_command command,
   }
 
   thd->net.no_send_error= 0;
-  result= dispatch_command(command, thd, (char *) arg, arg_length + 1);
+  result= dispatch_command(command, thd, (char *) arg, arg_length);
   thd->cur_data= 0;
 
   if (!skip_check)

mysql-test/r/sp.result

@@ -6620,6 +6620,182 @@ DROP TABLE t1;
 
 DROP PROCEDURE p1;
 DROP PROCEDURE p2;
+
+#
+# Bug#31035.
+#
+
+#
+# - Prepare.
+#
+
+DROP TABLE IF EXISTS t1;
+DROP FUNCTION IF EXISTS f1;
+DROP FUNCTION IF EXISTS f2;
+DROP FUNCTION IF EXISTS f3;
+DROP FUNCTION IF EXISTS f4;
+
+#
+# - Create required objects.
+#
+
+CREATE TABLE t1(c1 INT);
+
+INSERT INTO t1 VALUES (1), (2), (3);
+
+CREATE FUNCTION f1()
+RETURNS INT
+NOT DETERMINISTIC
+RETURN 1;
+
+CREATE FUNCTION f2(p INT)
+RETURNS INT
+NOT DETERMINISTIC
+RETURN 1;
+
+CREATE FUNCTION f3()
+RETURNS INT
+DETERMINISTIC
+RETURN 1;
+
+CREATE FUNCTION f4(p INT)
+RETURNS INT
+DETERMINISTIC
+RETURN 1;
+
+#
+# - Check.
+#
+
+SELECT f1() AS a FROM t1 GROUP BY a;
+a
+1
+
+SELECT f2(@a) AS a FROM t1 GROUP BY a;
+a
+1
+
+SELECT f3() AS a FROM t1 GROUP BY a;
+a
+1
+
+SELECT f4(0) AS a FROM t1 GROUP BY a;
+a
+1
+
+SELECT f4(@a) AS a FROM t1 GROUP BY a;
+a
+1
+
+#
+# - Cleanup.
+#
+
+DROP TABLE t1;
+DROP FUNCTION f1;
+DROP FUNCTION f2;
+DROP FUNCTION f3;
+DROP FUNCTION f4;
+
+#
+# Bug#31191.
+#
+
+#
+# - Prepare.
+#
+
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP FUNCTION IF EXISTS f1;
+
+#
+# - Create required objects.
+#
+
+CREATE TABLE t1 (
+id INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+barcode INT(8) UNSIGNED ZEROFILL nOT NULL,
+PRIMARY KEY  (id),
+UNIQUE KEY barcode (barcode)
+);
+
+INSERT INTO t1 (id, barcode) VALUES (1, 12345678);
+INSERT INTO t1 (id, barcode) VALUES (2, 12345679);
+
+CREATE TABLE test.t2 (
+id INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+barcode BIGINT(11) UNSIGNED ZEROFILL NOT NULL,
+PRIMARY KEY  (id)
+);
+
+INSERT INTO test.t2 (id, barcode) VALUES (1, 12345106708);
+INSERT INTO test.t2 (id, barcode) VALUES (2, 12345106709);
+
+CREATE FUNCTION f1(p INT(8))
+RETURNS BIGINT(11) UNSIGNED
+READS SQL DATA
+RETURN FLOOR(p/1000)*1000000 + 100000 + FLOOR((p MOD 1000)/10)*100 + (p MOD 10);
+
+#
+# - Check.
+#
+
+SELECT DISTINCT t1.barcode, f1(t1.barcode)
+FROM t1
+INNER JOIN t2
+ON f1(t1.barcode) = t2.barcode
+WHERE t1.barcode=12345678;
+barcode	f1(t1.barcode)
+12345678	12345106708
+
+#
+# - Cleanup.
+#
+
+DROP TABLE t1;
+DROP TABLE t2;
+DROP FUNCTION f1;
+
+#
+# Bug#31226.
+#
+
+#
+# - Prepare.
+#
+
+DROP TABLE IF EXISTS t1;
+DROP FUNCTION IF EXISTS f1;
+
+#
+# - Create required objects.
+#
+
+CREATE TABLE t1(id INT);
+
+INSERT INTO t1 VALUES (1), (2), (3);
+
+CREATE FUNCTION f1()
+RETURNS DATETIME
+NOT DETERMINISTIC NO SQL
+RETURN NOW();
+
+#
+# - Check.
+#
+
+SELECT f1() FROM t1 GROUP BY 1;
+f1()
+<timestamp>
+
+#
+# - Cleanup.
+#
+
+DROP TABLE t1;
+DROP FUNCTION f1;
+
 End of 5.0 tests
 
 #

mysql-test/t/sp.test

@@ -7581,6 +7581,296 @@ DROP TABLE t1;
 DROP PROCEDURE p1;
 DROP PROCEDURE p2;
 
+###########################################################################
+
+#
+# Bug#31035: select from function, group by result crasher.
+#
+
+###########################################################################
+
+--echo
+
+--echo #
+--echo # Bug#31035.
+--echo #
+
+--echo
+
+--echo #
+--echo # - Prepare.
+--echo #
+
+--echo
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP FUNCTION IF EXISTS f1;
+DROP FUNCTION IF EXISTS f2;
+DROP FUNCTION IF EXISTS f3;
+DROP FUNCTION IF EXISTS f4;
+--enable_warnings
+
+--echo
+
+--echo #
+--echo # - Create required objects.
+--echo #
+
+--echo
+
+CREATE TABLE t1(c1 INT);
+
+--echo
+
+INSERT INTO t1 VALUES (1), (2), (3);
+
+--echo
+
+CREATE FUNCTION f1()
+  RETURNS INT
+  NOT DETERMINISTIC
+    RETURN 1;
+
+--echo
+
+CREATE FUNCTION f2(p INT)
+  RETURNS INT
+  NOT DETERMINISTIC
+    RETURN 1;
+
+--echo
+
+CREATE FUNCTION f3()
+  RETURNS INT
+  DETERMINISTIC
+    RETURN 1;
+
+--echo
+
+CREATE FUNCTION f4(p INT)
+  RETURNS INT
+  DETERMINISTIC
+    RETURN 1;
+
+--echo
+
+--echo #
+--echo # - Check.
+--echo #
+
+--echo
+
+# Not deterministic function, no arguments.
+
+SELECT f1() AS a FROM t1 GROUP BY a;
+
+--echo
+
+# Not deterministic function, non-constant argument.
+
+SELECT f2(@a) AS a FROM t1 GROUP BY a;
+
+--echo
+
+# Deterministic function, no arguments.
+
+SELECT f3() AS a FROM t1 GROUP BY a;
+
+--echo
+
+# Deterministic function, constant argument.
+
+SELECT f4(0) AS a FROM t1 GROUP BY a;
+
+--echo
+
+# Deterministic function, non-constant argument.
+
+SELECT f4(@a) AS a FROM t1 GROUP BY a;
+
+--echo
+
+--echo #
+--echo # - Cleanup.
+--echo #
+
+--echo
+
+DROP TABLE t1;
+DROP FUNCTION f1;
+DROP FUNCTION f2;
+DROP FUNCTION f3;
+DROP FUNCTION f4;
+
+--echo
+
+###########################################################################
+
+#
+# Bug#31191: JOIN in combination with stored function crashes the server.
+#
+
+###########################################################################
+
+--echo #
+--echo # Bug#31191.
+--echo #
+
+--echo
+
+--echo #
+--echo # - Prepare.
+--echo #
+
+--echo
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP FUNCTION IF EXISTS f1;
+--enable_warnings
+
+--echo
+
+--echo #
+--echo # - Create required objects.
+--echo #
+
+--echo
+
+CREATE TABLE t1 (
+   id INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+   barcode INT(8) UNSIGNED ZEROFILL nOT NULL,
+   PRIMARY KEY  (id),
+   UNIQUE KEY barcode (barcode)
+);
+
+--echo
+
+INSERT INTO t1 (id, barcode) VALUES (1, 12345678);
+INSERT INTO t1 (id, barcode) VALUES (2, 12345679);
+
+--echo
+
+CREATE TABLE test.t2 (
+   id INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+   barcode BIGINT(11) UNSIGNED ZEROFILL NOT NULL,
+   PRIMARY KEY  (id)
+);
+
+--echo
+
+INSERT INTO test.t2 (id, barcode) VALUES (1, 12345106708);
+INSERT INTO test.t2 (id, barcode) VALUES (2, 12345106709);
+
+--echo
+
+CREATE FUNCTION f1(p INT(8))
+  RETURNS BIGINT(11) UNSIGNED
+  READS SQL DATA
+    RETURN FLOOR(p/1000)*1000000 + 100000 + FLOOR((p MOD 1000)/10)*100 + (p MOD 10);
+
+--echo
+
+--echo #
+--echo # - Check.
+--echo #
+
+--echo
+
+SELECT DISTINCT t1.barcode, f1(t1.barcode)
+FROM t1
+INNER JOIN t2
+ON f1(t1.barcode) = t2.barcode
+WHERE t1.barcode=12345678;
+
+--echo
+
+--echo #
+--echo # - Cleanup.
+--echo #
+
+--echo
+
+DROP TABLE t1;
+DROP TABLE t2;
+DROP FUNCTION f1;
+
+--echo
+
+###########################################################################
+
+#
+# Bug#31226: Group by function crashes mysql.
+#
+
+###########################################################################
+
+--echo #
+--echo # Bug#31226.
+--echo #
+
+--echo
+
+--echo #
+--echo # - Prepare.
+--echo #
+
+--echo
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP FUNCTION IF EXISTS f1;
+--enable_warnings
+
+--echo
+
+--echo #
+--echo # - Create required objects.
+--echo #
+
+--echo
+
+CREATE TABLE t1(id INT);
+
+--echo
+
+INSERT INTO t1 VALUES (1), (2), (3);
+
+--echo
+
+CREATE FUNCTION f1()
+  RETURNS DATETIME
+  NOT DETERMINISTIC NO SQL
+    RETURN NOW();
+
+--echo
+
+--echo #
+--echo # - Check.
+--echo #
+
+--echo
+
+--replace_column 1 <timestamp>
+SELECT f1() FROM t1 GROUP BY 1;
+
+--echo
+
+--echo #
+--echo # - Cleanup.
+--echo #
+
+--echo
+
+DROP TABLE t1;
+DROP FUNCTION f1;
+
+--echo
+
+###########################################################################
+
 --echo End of 5.0 tests
 
 ###########################################################################

mysql-test/t/upgrade.test

 -- source include/not_embedded.inc
 
+# Temporary disabled on windows,
+# because of --exec mkdir
+# TODO: implement Bug#31004 and remove this limitation
+--source include/not_windows.inc
+
 --disable_warnings
 drop database if exists `mysqltest1`;
 drop database if exists `mysqltest-1`;
@@ -60,7 +65,6 @@ drop table t1;
 # Bug#28360 (RENAME DATABASE destroys routines)
 #
 
-
 --disable_warnings
 drop database if exists `tabc`;
 drop database if exists `a-b-c`;

mysys/my_winthread.c

@@ -40,6 +40,29 @@ void win_pthread_init(void)
   pthread_mutex_init(&THR_LOCK_thread,MY_MUTEX_INIT_FAST);
 }
 
+
+/**
+   Adapter to @c pthread_mutex_trylock()
+
+   @retval 0      Mutex was acquired
+   @retval EBUSY  Mutex was already locked by a thread
+ */
+int
+win_pthread_mutex_trylock(pthread_mutex_t *mutex)
+{
+  if (TryEnterCriticalSection(mutex))
+  {
+    /* Don't allow recursive lock */
+    if (mutex->RecursionCount > 1){
+      LeaveCriticalSection(mutex);
+      return EBUSY;
+    }
+    return 0;
+  }
+  return EBUSY;
+}
+
+
 /*
 ** We have tried to use '_beginthreadex' instead of '_beginthread' here
 ** but in this case the program leaks about 512 characters for each

mysys/thr_mutex.c

@@ -91,7 +91,7 @@ int safe_mutex_init(safe_mutex_t *mp,
 }
 
 
-int safe_mutex_lock(safe_mutex_t *mp,const char *file, uint line)
+int safe_mutex_lock(safe_mutex_t *mp, my_bool try_lock, const char *file, uint line)
 {
   int error;
   if (!mp->file)
@@ -104,15 +104,50 @@ int safe_mutex_lock(safe_mutex_t *mp,const char *file, uint line)
   }
 
   pthread_mutex_lock(&mp->global);
-  if (mp->count > 0 && pthread_equal(pthread_self(),mp->thread))
+  if (mp->count > 0)
   {
-    fprintf(stderr,"safe_mutex: Trying to lock mutex at %s, line %d, when the mutex was already locked at %s, line %d in thread %s\n",
-	    file,line,mp->file, mp->line, my_thread_name());
-    fflush(stderr);
-    abort();
+    if (try_lock)
+    {
+      pthread_mutex_unlock(&mp->global);
+      return EBUSY;
+    }
+    else if (pthread_equal(pthread_self(),mp->thread))
+    {
+      fprintf(stderr,
+              "safe_mutex: Trying to lock mutex at %s, line %d, when the"
+              " mutex was already locked at %s, line %d in thread %s\n",
+              file,line,mp->file, mp->line, my_thread_name());
+      fflush(stderr);
+      abort();
+    }
   }
   pthread_mutex_unlock(&mp->global);
-  error=pthread_mutex_lock(&mp->mutex);
+
+  /*
+    If we are imitating trylock(), we need to take special
+    precautions.
+
+    - We cannot use pthread_mutex_lock() only since another thread can
+      overtake this thread and take the lock before this thread
+      causing pthread_mutex_trylock() to hang. In this case, we should
+      just return EBUSY. Hence, we use pthread_mutex_trylock() to be
+      able to return immediately.
+
+    - We cannot just use trylock() and continue execution below, since
+      this would generate an error and abort execution if the thread
+      was overtaken and trylock() returned EBUSY . In this case, we
+      instead just return EBUSY, since this is the expected behaviour
+      of trylock().
+   */
+  if (try_lock)
+  {
+    error= pthread_mutex_trylock(&mp->mutex);
+    if (error == EBUSY)
+      return error;
+  }
+  else
+    error= pthread_mutex_lock(&mp->mutex);
+
   if (error || (error=pthread_mutex_lock(&mp->global)))
   {
     fprintf(stderr,"Got error %d when trying to lock mutex at %s, line %d\n",

sql/item_func.cc

@@ -5592,8 +5592,13 @@ Item_func_sp::fix_fields(THD *thd, Item **ref)
     
 #endif /* ! NO_EMBEDDED_ACCESS_CHECKS */
   }
+
   if (!m_sp->m_chistics->detistic)
-   used_tables_cache |= RAND_TABLE_BIT;
+  {
+    used_tables_cache |= RAND_TABLE_BIT;
+    const_item_cache= FALSE;
+  }
+
   DBUG_RETURN(res);
 }
 
@@ -5601,8 +5606,12 @@ Item_func_sp::fix_fields(THD *thd, Item **ref)
 void Item_func_sp::update_used_tables()
 {
   Item_func::update_used_tables();
+
   if (!m_sp->m_chistics->detistic)
-   used_tables_cache |= RAND_TABLE_BIT;
+  {
+    used_tables_cache |= RAND_TABLE_BIT;
+    const_item_cache= FALSE;
+  }
 }
 
 

sql/mysql_priv.h

@@ -917,7 +917,6 @@ void decrease_user_connections(USER_CONN *uc);
 void thd_init_client_charset(THD *thd, uint cs_number);
 bool setup_connection_thread_globals(THD *thd);
 bool login_connection(THD *thd);
-void prepare_new_connection_state(THD* thd);
 void end_connection(THD *thd);
 
 bool mysql_create_db(THD *thd, char *db, HA_CREATE_INFO *create, bool silent);

sql/sql_class.cc

@@ -585,6 +585,12 @@ void THD::init(void)
   if (variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES)
     server_status|= SERVER_STATUS_NO_BACKSLASH_ESCAPES;
   options= thd_startup_options;
+
+  if (variables.max_join_size == HA_POS_ERROR)
+    options |= OPTION_BIG_SELECTS;
+  else
+    options &= ~OPTION_BIG_SELECTS;
+
   transaction.all.modified_non_trans_table= transaction.stmt.modified_non_trans_table= FALSE;
   open_options=ha_open_options;
   update_lock_default= (variables.low_priority_updates ?

sql/sql_connect.cc

@@ -933,7 +933,7 @@ bool login_connection(THD *thd)
   NET *net= &thd->net;
   Security_context *sctx= thd->security_ctx;
   DBUG_ENTER("login_connection");
-  DBUG_PRINT("info", ("handle_one_connection called by thread %lu",
+  DBUG_PRINT("info", ("login_connection called by thread %lu",
                       thd->thread_id));
 
   net->no_send_error= 0;
@@ -973,21 +973,29 @@ void end_connection(THD *thd)
   plugin_thdvar_cleanup(thd);
   if (thd->user_connect)
     decrease_user_connections(thd->user_connect);
+
+  if (thd->killed ||
+      net->error && net->vio != 0 && net->report_error)
+  {
+    statistic_increment(aborted_threads,&LOCK_status);
+  }
+
   if (net->error && net->vio != 0 && net->report_error)
   {
-    Security_context *sctx= thd->security_ctx;
     if (!thd->killed && thd->variables.log_warnings > 1)
+    {
+      Security_context *sctx= thd->security_ctx;
+
       sql_print_warning(ER(ER_NEW_ABORTING_CONNECTION),
                         thd->thread_id,(thd->db ? thd->db : "unconnected"),
                         sctx->user ? sctx->user : "unauthenticated",
                         sctx->host_or_ip,
                         (net->last_errno ? ER(net->last_errno) :
                          ER(ER_UNKNOWN_ERROR)));
+    }
+
     net_send_error(thd, net->last_errno, NullS);
-    statistic_increment(aborted_threads,&LOCK_status);
   }
-  else if (thd->killed)
-    statistic_increment(aborted_threads,&LOCK_status);
 }
 
 
@@ -995,7 +1003,7 @@ void end_connection(THD *thd)
   Initialize THD to handle queries
 */
 
-void prepare_new_connection_state(THD* thd)
+static void prepare_new_connection_state(THD* thd)
 {
   Security_context *sctx= thd->security_ctx;
 

sql/sql_parse.cc

@@ -86,7 +86,6 @@ const char *xa_state_names[]={
   "NON-EXISTING", "ACTIVE", "IDLE", "PREPARED"
 };
 
-
 static void unlock_locked_tables(THD *thd)
 {
   if (thd->locked_tables)
@@ -681,12 +680,12 @@ bool do_command(THD *thd)
     DBUG_PRINT("info",("Got error %d reading command from socket %s",
 		       net->error,
 		       vio_description(net->vio)));
+
     /* Check if we can continue without closing the connection */
+
     if (net->error != 3)
-    {
-      statistic_increment(aborted_threads,&LOCK_status);
       DBUG_RETURN(TRUE);			// We have to close it.
-    }
+
     net_send_error(thd, net->last_errno, NullS);
     net->error= 0;
     DBUG_RETURN(FALSE);

tests/mysql_client_test.c

@@ -16819,6 +16819,176 @@ static void test_bug30472()
   mysql_close(&con);
 }
 
+static void bug20023_change_user(MYSQL *con)
+{
+  DIE_IF(mysql_change_user(con,
+                           opt_user,
+                           opt_password,
+                           opt_db ? opt_db : "test"));
+}
+
+static void bug20023_query_int_variable(MYSQL *con,
+                                        const char *var_name,
+                                        int *var_value)
+{
+  MYSQL_RES *rs;
+  MYSQL_ROW row;
+
+  char query_buffer[MAX_TEST_QUERY_LENGTH];
+
+  my_snprintf(query_buffer,
+          sizeof (query_buffer),
+          "SELECT @@%s",
+          (const char *) var_name);
+
+  DIE_IF(mysql_query(con, query_buffer));
+  DIE_UNLESS(rs= mysql_store_result(con));
+  DIE_UNLESS(row= mysql_fetch_row(rs));
+  *var_value= atoi(row[0]);
+  mysql_free_result(rs);
+}
+
+static void test_bug20023()
+{
+  MYSQL con;
+
+  int sql_big_selects_orig;
+  int max_join_size_orig;
+
+  int sql_big_selects_2;
+  int sql_big_selects_3;
+  int sql_big_selects_4;
+  int sql_big_selects_5;
+
+  char query_buffer[MAX_TEST_QUERY_LENGTH];
+
+  /* Create a new connection. */
+
+  DIE_UNLESS(mysql_init(&con));
+
+  DIE_UNLESS(mysql_real_connect(&con,
+                                opt_host,
+                                opt_user,
+                                opt_password,
+                                opt_db ? opt_db : "test",
+                                opt_port,
+                                opt_unix_socket,
+                                CLIENT_FOUND_ROWS));
+
+  /***********************************************************************
+   Remember original SQL_BIG_SELECTS, MAX_JOIN_SIZE values.
+  ***********************************************************************/
+
+  bug20023_query_int_variable(&con,
+                              "session.sql_big_selects",
+                              &sql_big_selects_orig);
+
+  bug20023_query_int_variable(&con,
+                              "global.max_join_size",
+                              &max_join_size_orig);
+
+  /***********************************************************************
+   Test that COM_CHANGE_USER resets the SQL_BIG_SELECTS to the initial value.
+  ***********************************************************************/
+
+  /* Issue COM_CHANGE_USER. */
+
+  bug20023_change_user(&con);
+
+  /* Query SQL_BIG_SELECTS. */
+
+  bug20023_query_int_variable(&con,
+                              "session.sql_big_selects",
+                              &sql_big_selects_2);
+
+  /* Check that SQL_BIG_SELECTS is reset properly. */
+
+  DIE_UNLESS(sql_big_selects_orig == sql_big_selects_2);
+
+  /***********************************************************************
+   Test that if MAX_JOIN_SIZE set to non-default value,
+   SQL_BIG_SELECTS will be 0.
+  ***********************************************************************/
+
+  /* Set MAX_JOIN_SIZE to some non-default value. */
+
+  DIE_IF(mysql_query(&con, "SET @@global.max_join_size = 10000"));
+  DIE_IF(mysql_query(&con, "SET @@session.max_join_size = default"));
+
+  /* Issue COM_CHANGE_USER. */
+
+  bug20023_change_user(&con);
+
+  /* Query SQL_BIG_SELECTS. */
+
+  bug20023_query_int_variable(&con,
+                              "session.sql_big_selects",
+                              &sql_big_selects_3);
+
+  /* Check that SQL_BIG_SELECTS is 0. */
+
+  DIE_UNLESS(sql_big_selects_3 == 0);
+
+  /***********************************************************************
+   Test that if MAX_JOIN_SIZE set to default value,
+   SQL_BIG_SELECTS will be 1.
+  ***********************************************************************/
+
+  /* Set MAX_JOIN_SIZE to the default value (-1). */
+
+  DIE_IF(mysql_query(&con, "SET @@global.max_join_size = -1"));
+  DIE_IF(mysql_query(&con, "SET @@session.max_join_size = default"));
+
+  /* Issue COM_CHANGE_USER. */
+
+  bug20023_change_user(&con);
+
+  /* Query SQL_BIG_SELECTS. */
+
+  bug20023_query_int_variable(&con,
+                              "session.sql_big_selects",
+                              &sql_big_selects_4);
+
+  /* Check that SQL_BIG_SELECTS is 1. */
+
+  DIE_UNLESS(sql_big_selects_4 == 1);
+
+  /***********************************************************************
+   Restore MAX_JOIN_SIZE.
+   Check that SQL_BIG_SELECTS will be the original one.
+  ***********************************************************************/
+
+  /* Restore MAX_JOIN_SIZE. */
+
+  my_snprintf(query_buffer,
+           sizeof (query_buffer),
+           "SET @@global.max_join_size = %d",
+           (int) max_join_size_orig);
+
+  DIE_IF(mysql_query(&con, query_buffer));
+  DIE_IF(mysql_query(&con, "SET @@session.max_join_size = default"));
+
+  /* Issue COM_CHANGE_USER. */
+
+  bug20023_change_user(&con);
+
+  /* Query SQL_BIG_SELECTS. */
+
+  bug20023_query_int_variable(&con,
+                              "session.sql_big_selects",
+                              &sql_big_selects_5);
+
+  /* Check that SQL_BIG_SELECTS is 1. */
+
+  DIE_UNLESS(sql_big_selects_5 == sql_big_selects_orig);
+
+  /***********************************************************************
+   That's it. Cleanup.
+  ***********************************************************************/
+
+  mysql_close(&con);
+}
+
 
 /*
   Read and parse arguments and MySQL options from my.cnf
@@ -17115,6 +17285,7 @@ static struct my_tests_st my_tests[]= {
   { "test_bug29306", test_bug29306 },
   { "test_change_user", test_change_user },
   { "test_bug30472", test_bug30472 },
+  { "test_bug20023", test_bug20023 },
   { 0, 0 }
 };