Merge 10.3 into 10.4

13 files changed, 114 insertions, 100 deletions

diff --git a/sql/CMakeLists.txt b/sql/CMakeLists.txt
index 52fab2a029f..bab8e67fdac 100644
--- a/sql/CMakeLists.txt
+++ b/sql/CMakeLists.txt
@@ -418,15 +418,18 @@ IF(WIN32 AND TARGET mysqld AND NOT CMAKE_CROSSCOMPILING)
   ENDIF()
   MAKE_DIRECTORY(${CMAKE_CURRENT_BINARY_DIR}/data)
   ADD_CUSTOM_COMMAND(
-     OUTPUT  ${CMAKE_CURRENT_BINARY_DIR}/initdb.dep
-     COMMAND ${CMAKE_COMMAND} ${CONFIG_PARAM}
-       -DTOP_SRCDIR="${CMAKE_SOURCE_DIR}"
-       -DBINDIR="${CMAKE_CURRENT_BINARY_DIR}"
-       -DMYSQLD_EXECUTABLE="$<TARGET_FILE:mysqld>"
-       -DCMAKE_CFG_INTDIR="${CMAKE_CFG_INTDIR}"
-       -P ${CMAKE_SOURCE_DIR}/cmake/create_initial_db.cmake
+     OUTPUT initdb.dep
+     COMMAND ${CMAKE_COMMAND} -E remove_directory data
+     COMMAND ${CMAKE_COMMAND} -E make_directory data
+     COMMAND ${CMAKE_COMMAND} -E chdir data ${CMAKE_COMMAND}
+     ${CONFIG_PARAM}
+     -DTOP_SRCDIR="${CMAKE_SOURCE_DIR}"
+     -DBINDIR="${CMAKE_CURRENT_BINARY_DIR}"
+     -DMYSQLD_EXECUTABLE="$<TARGET_FILE:mysqld>"
+     -DCMAKE_CFG_INTDIR="${CMAKE_CFG_INTDIR}"
+     -P ${CMAKE_SOURCE_DIR}/cmake/create_initial_db.cmake
      COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/initdb.dep
-     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/data
+     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/
      DEPENDS mysqld
   )
   ADD_CUSTOM_TARGET(initial_database  
diff --git a/sql/item.cc b/sql/item.cc
index dc39755f63d..7d7d50da2cf 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -3225,12 +3225,13 @@ bool Item_field::get_date(THD *thd, MYSQL_TIME *ltime,date_mode_t fuzzydate)
 
 bool Item_field::get_date_result(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate)
 {
-  if (result_field->is_null() || result_field->get_date(ltime,fuzzydate))
+  if ((null_value= result_field->is_null()) ||
+      result_field->get_date(ltime, fuzzydate))
   {
     bzero((char*) ltime,sizeof(*ltime));
-    return (null_value= 1);
+    return true;
   }
-  return (null_value= 0);
+  return false;
 }
 
 
@@ -8229,7 +8230,7 @@ bool Item_ref::val_native(THD *thd, Native *to)
 longlong Item_ref::val_datetime_packed(THD *thd)
 {
   DBUG_ASSERT(fixed);
-  longlong tmp= (*ref)->val_datetime_packed(thd);
+  longlong tmp= (*ref)->val_datetime_packed_result(thd);
   null_value= (*ref)->null_value;
   return tmp;
 }
@@ -8238,7 +8239,7 @@ longlong Item_ref::val_datetime_packed(THD *thd)
 longlong Item_ref::val_time_packed(THD *thd)
 {
   DBUG_ASSERT(fixed);
-  longlong tmp= (*ref)->val_time_packed(thd);
+  longlong tmp= (*ref)->val_time_packed_result(thd);
   null_value= (*ref)->null_value;
   return tmp;
 }
diff --git a/sql/item_timefunc.cc b/sql/item_timefunc.cc
index 3b2ac55c59d..924fdecffa9 100644
--- a/sql/item_timefunc.cc
+++ b/sql/item_timefunc.cc
@@ -1101,9 +1101,10 @@ longlong Item_func_weekday::val_int()
 {
   DBUG_ASSERT(fixed == 1);
   THD *thd= current_thd;
-  Datetime d(thd, args[0], Datetime::Options(TIME_NO_ZEROS, thd));
-  return ((null_value= !d.is_valid_datetime())) ? 0 :
-         calc_weekday(d.daynr(), odbc_type) + MY_TEST(odbc_type);
+  Datetime dt(thd, args[0], Datetime::Options(TIME_NO_ZEROS, thd));
+  if ((null_value= !dt.is_valid_datetime()))
+    return 0;
+  return dt.weekday(odbc_type) + MY_TEST(odbc_type);
 }
 
 bool Item_func_dayname::fix_length_and_dec()
@@ -1122,14 +1123,15 @@ bool Item_func_dayname::fix_length_and_dec()
 String* Item_func_dayname::val_str(String* str)
 {
   DBUG_ASSERT(fixed == 1);
-  uint weekday=(uint) val_int();		// Always Item_func_weekday()
   const char *day_name;
   uint err;
+  THD *thd= current_thd;
+  Datetime dt(thd, args[0], Datetime::Options(TIME_NO_ZEROS, thd));
 
-  if (null_value)
+  if ((null_value= !dt.is_valid_datetime()))
     return (String*) 0;
-  
-  day_name= locale->day_names->type_names[weekday];
+
+  day_name= locale->day_names->type_names[dt.weekday(false)];
   str->copy(day_name, (uint) strlen(day_name), &my_charset_utf8_bin,
 	    collation.collation, &err);
   return str;
diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index fe9dc8b43e2..8a69a0a3d5a 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -422,20 +422,13 @@ public:
 };
 
 
-class Item_func_weekday :public Item_func
+class Item_func_weekday :public Item_long_func
 {
   bool odbc_type;
 public:
   Item_func_weekday(THD *thd, Item *a, bool type_arg):
-    Item_func(thd, a), odbc_type(type_arg) { collation.set_numeric(); }
+    Item_long_func(thd, a), odbc_type(type_arg) { }
   longlong val_int();
-  double val_real() { DBUG_ASSERT(fixed == 1); return (double) val_int(); }
-  String *val_str(String *str)
-  {
-    DBUG_ASSERT(fixed == 1);
-    str->set(val_int(), &my_charset_bin);
-    return null_value ? 0 : str;
-  }
   const char *func_name() const
   {
      return (odbc_type ? "dayofweek" : "weekday");
@@ -444,7 +437,6 @@ public:
   {
     return type_handler()->Item_get_date_with_warn(thd, this, ltime, fuzzydate);
   }
-  const Type_handler *type_handler() const { return &type_handler_long; }
   bool fix_length_and_dec()
   {
     decimals= 0;
@@ -462,11 +454,11 @@ public:
   { return get_item_copy<Item_func_weekday>(thd, this); }
 };
 
-class Item_func_dayname :public Item_func_weekday
+class Item_func_dayname :public Item_str_func
 {
   MY_LOCALE *locale;
  public:
-  Item_func_dayname(THD *thd, Item *a): Item_func_weekday(thd, a, 0) {}
+  Item_func_dayname(THD *thd, Item *a): Item_str_func(thd, a) {}
   const char *func_name() const { return "dayname"; }
   String *val_str(String *str);
   const Type_handler *type_handler() const { return &type_handler_varchar; }
@@ -476,6 +468,12 @@ class Item_func_dayname :public Item_func_weekday
   {
     return mark_unsupported_function(func_name(), "()", arg, VCOL_SESSION_FUNC);
   }
+  bool check_valid_arguments_processor(void *int_arg)
+  {
+    return !has_date_args();
+  }
+  Item *get_copy(THD *thd)
+  { return get_item_copy<Item_func_dayname>(thd, this); }
 };
 
 
diff --git a/sql/sql_audit.h b/sql/sql_audit.h
index 59cced13b0a..97317203e34 100644
--- a/sql/sql_audit.h
+++ b/sql/sql_audit.h
@@ -284,7 +284,9 @@ void mysql_audit_notify_connection_change_user(THD *thd)
 }
 
 static inline
-void mysql_audit_external_lock(THD *thd, TABLE_SHARE *share, int lock)
+void mysql_audit_external_lock_ex(THD *thd, my_thread_id thread_id,
+    const char *user, const char *host, const char *ip, query_id_t query_id,
+    TABLE_SHARE *share, int lock)
 {
   if (lock != F_UNLCK && mysql_audit_table_enabled())
   {
@@ -293,25 +295,33 @@ void mysql_audit_external_lock(THD *thd, TABLE_SHARE *share, int lock)
 
     event.event_subclass= MYSQL_AUDIT_TABLE_LOCK;
     event.read_only= lock == F_RDLCK;
-    event.thread_id= (unsigned long)thd->thread_id;
-    event.user= sctx->user;
+    event.thread_id= (unsigned long)thread_id;
+    event.user= user;
     event.priv_user= sctx->priv_user;
     event.priv_host= sctx->priv_host;
     event.external_user= sctx->external_user;
     event.proxy_user= sctx->proxy_user;
-    event.host= sctx->host;
-    event.ip= sctx->ip;
+    event.host= host;
+    event.ip= ip;
     event.database= share->db;
     event.table= share->table_name;
     event.new_database= null_clex_str;
     event.new_table= null_clex_str;
-    event.query_id= thd->query_id;
+    event.query_id= query_id;
 
     mysql_audit_notify(thd, MYSQL_AUDIT_TABLE_CLASS, &event);
   }
 }
 
 static inline
+void mysql_audit_external_lock(THD *thd, TABLE_SHARE *share, int lock)
+{
+  mysql_audit_external_lock_ex(thd, thd->thread_id, thd->security_ctx->user,
+      thd->security_ctx->host, thd->security_ctx->ip, thd->query_id,
+      share, lock);
+}
+
+static inline
 void mysql_audit_create_table(TABLE *table)
 {
   if (mysql_audit_table_enabled())
diff --git a/sql/sql_insert.cc b/sql/sql_insert.cc
index c8f4ac05efc..807dd94c6f0 100644
--- a/sql/sql_insert.cc
+++ b/sql/sql_insert.cc
@@ -2193,36 +2193,16 @@ public:
     passed from connection thread to the handler thread.
   */
   MDL_request grl_protection;
-  my_thread_id orig_thread_id;
-  void set_default_user()
-  {
-    thd.security_ctx->user=(char*) delayed_user;
-    thd.security_ctx->host=(char*) my_localhost;
-    thd.security_ctx->ip= NULL;
-    thd.query_id= 0;
-    thd.thread_id= orig_thread_id;
-  }
-
-  void set_user_from_row(const delayed_row *r)
-  {
-    if (r)
-    {
-      thd.security_ctx->user= r->user;
-      thd.security_ctx->host= r->host;
-      thd.security_ctx->ip= r->ip;
-      thd.query_id= r->query_id;
-      thd.thread_id= r->thread_id;
-    }
-  }
-
   Delayed_insert(SELECT_LEX *current_select)
     :locks_in_memory(0), thd(next_thread_id()),
      table(0),tables_in_use(0), stacked_inserts(0),
      status(0), retry(0), handler_thread_initialized(FALSE), group_count(0)
   {
     DBUG_ENTER("Delayed_insert constructor");
-    orig_thread_id= thd.thread_id;
-    set_default_user();
+    thd.security_ctx->user=(char*) delayed_user;
+    thd.security_ctx->host=(char*) my_localhost;
+    thd.security_ctx->ip= NULL;
+    thd.query_id= 0;
     strmake_buf(thd.security_ctx->priv_user, thd.security_ctx->user);
     thd.current_tablenr=0;
     thd.set_command(COM_DELAYED_INSERT);
@@ -3208,7 +3188,6 @@ pthread_handler_t handle_delayed_insert(void *arg)
       if (di->tables_in_use && ! thd->lock &&
           (!thd->killed || di->stacked_inserts))
       {
-        di->set_user_from_row(di->rows.head());
         /*
           Request for new delayed insert.
           Lock the table, but avoid to be blocked by a global read lock.
@@ -3230,16 +3209,18 @@ pthread_handler_t handle_delayed_insert(void *arg)
       {
         delayed_row *row;
         I_List_iterator<delayed_row> it(di->rows);
+        my_thread_id cur_thd= di->thd.thread_id;
+
         while ((row= it++))
         {
-          if (di->thd.thread_id != row->thread_id)
+          if (cur_thd != row->thread_id)
           {
-            di->set_user_from_row(row);
-            mysql_audit_external_lock(&di->thd, di->table->s, F_WRLCK);
+            mysql_audit_external_lock_ex(&di->thd, row->thread_id,
+                row->user, row->host, row->ip, row->query_id,
+                di->table->s, F_WRLCK);
+            cur_thd= row->thread_id;
           }
         }
-        di->set_default_user();
-
         if (di->handle_inserts())
         {
           /* Some fatal error */
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index 9d22eb1a8cc..0983cea44d0 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -1679,28 +1679,6 @@ public:
   uint sroutines_list_own_elements;
 
   /**
-    Locking state of tables in this particular statement.
-
-    If we under LOCK TABLES or in prelocked mode we consider tables
-    for the statement to be "locked" if there was a call to lock_tables()
-    (which called handler::start_stmt()) for tables of this statement
-    and there was no matching close_thread_tables() call.
-
-    As result this state may differ significantly from one represented
-    by Open_tables_state::lock/locked_tables_mode more, which are always
-    "on" under LOCK TABLES or in prelocked mode.
-  */
-  enum enum_lock_tables_state {
-    LTS_NOT_LOCKED = 0,
-    LTS_LOCKED
-  };
-  enum_lock_tables_state lock_tables_state;
-  bool is_query_tables_locked()
-  {
-    return (lock_tables_state == LTS_LOCKED);
-  }
-
-  /**
     Number of tables which were open by open_tables() and to be locked
     by lock_tables().
     Note that we set this member only in some cases, when this value
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index a685c948a3d..d9d9c229c2f 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -2121,6 +2121,7 @@ JOIN::optimize_inner()
         zero_result_cause= "Zero limit";
       }
       table_count= top_join_tab_count= 0;
+      handle_implicit_grouping_with_window_funcs();
       error= 0;
       subq_exit_fl= true;
       goto setup_subq_exit;
@@ -2168,6 +2169,7 @@ JOIN::optimize_inner()
         table_count= top_join_tab_count= 0;
 	error=0;
         subq_exit_fl= true;
+        handle_implicit_grouping_with_window_funcs();
         goto setup_subq_exit;
       }
       if (res > 1)
@@ -2183,6 +2185,7 @@ JOIN::optimize_inner()
       tables_list= 0;				// All tables resolved
       select_lex->min_max_opt_list.empty();
       const_tables= top_join_tab_count= table_count;
+      handle_implicit_grouping_with_window_funcs();
       /*
         Extract all table-independent conditions and replace the WHERE
         clause with them. All other conditions were computed by opt_sum_query
@@ -2331,6 +2334,7 @@ int JOIN::optimize_stage2()
     zero_result_cause= "no matching row in const table";
     DBUG_PRINT("error",("Error: %s", zero_result_cause));
     error= 0;
+    handle_implicit_grouping_with_window_funcs();
     goto setup_subq_exit;
   }
   if (!(thd->variables.option_bits & OPTION_BIG_SELECTS) &&
@@ -2362,6 +2366,7 @@ int JOIN::optimize_stage2()
     zero_result_cause=
       "Impossible WHERE noticed after reading const tables";
     select_lex->mark_const_derived(zero_result_cause);
+    handle_implicit_grouping_with_window_funcs();
     goto setup_subq_exit;
   }
 
@@ -2524,6 +2529,7 @@ int JOIN::optimize_stage2()
     zero_result_cause=
       "Impossible WHERE noticed after reading const tables";
     select_lex->mark_const_derived(zero_result_cause);
+    handle_implicit_grouping_with_window_funcs();
     goto setup_subq_exit;
   }
 
@@ -15741,7 +15747,7 @@ static COND* substitute_for_best_equal_field(THD *thd, JOIN_TAB *context_tab,
     }	 
   }
   else if (cond->type() == Item::FUNC_ITEM && 
-           ((Item_cond*) cond)->functype() == Item_func::MULT_EQUAL_FUNC)
+           ((Item_func*) cond)->functype() == Item_func::MULT_EQUAL_FUNC)
   {
     item_equal= (Item_equal *) cond;
     item_equal->sort(&compare_fields_by_table_order, table_join_idx);
@@ -19614,7 +19620,8 @@ void set_postjoin_aggr_write_func(JOIN_TAB *tab)
     }
   }
   else if (join->sort_and_group && !tmp_tbl->precomputed_group_by &&
-           !join->sort_and_group_aggr_tab && join->tables_list)
+           !join->sort_and_group_aggr_tab && join->tables_list &&
+           join->top_join_tab_count)
   {
     DBUG_PRINT("info",("Using end_write_group"));
     aggr->set_write_func(end_write_group);
@@ -25041,7 +25048,8 @@ change_to_use_tmp_fields(THD *thd, Ref_ptr_array ref_pointer_array,
   for (uint i= 0; (item= it++); i++)
   {
     Field *field;
-    if (item->with_sum_func() && item->type() != Item::SUM_FUNC_ITEM)
+    if ((item->with_sum_func() && item->type() != Item::SUM_FUNC_ITEM) ||
+       item->with_window_func)
       item_field= item;
     else if (item->type() == Item::FIELD_ITEM)
     {
@@ -28607,6 +28615,28 @@ Item *remove_pushed_top_conjuncts(THD *thd, Item *cond)
 }
 
 
+/*
+  There are 5 cases in which we shortcut the join optimization process as we
+  conclude that the join would be a degenerate one
+    1) IMPOSSIBLE WHERE
+    2) MIN/MAX optimization (@see opt_sum_query)
+    3) EMPTY CONST TABLE
+  If a window function is present in any of the above cases then to get the
+  result of the window function, we need to execute it. So we need to
+  create a temporary table for its execution. Here we need to take in mind
+  that aggregate functions and non-aggregate function need not be executed.
+
+*/
+
+void JOIN::handle_implicit_grouping_with_window_funcs()
+{
+  if (select_lex->have_window_funcs() && send_row_on_empty_set())
+  {
+    const_tables= top_join_tab_count= table_count= 0;
+  }
+}
+
+
 /**
   @brief
     Look for provision of the select_handler interface by a foreign engine
diff --git a/sql/sql_select.h b/sql/sql_select.h
index dcb8326ed8c..b9043a851e7 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -1127,6 +1127,7 @@ protected:
                                Join_plan_state *save_to);
   /* Choose a subquery plan for a table-less subquery. */
   bool choose_tableless_subquery_plan();
+  void handle_implicit_grouping_with_window_funcs();
 
 public:
   void save_query_plan(Join_plan_state *save_to);
diff --git a/sql/sql_type.h b/sql/sql_type.h
index 0dd82f3dfaf..04eb5a25891 100644
--- a/sql/sql_type.h
+++ b/sql/sql_type.h
@@ -1785,6 +1785,10 @@ protected:
   {
     return (ulong) ::calc_daynr((uint) year, (uint) month, (uint) day);
   }
+  int weekday(bool sunday_first_day_of_week) const
+  {
+    return ::calc_weekday(daynr(), sunday_first_day_of_week);
+  }
   ulong dayofyear() const
   {
     return (ulong) (daynr() - ::calc_daynr(year, 1, 1) + 1);
@@ -2165,6 +2169,11 @@ public:
     DBUG_ASSERT(is_valid_datetime_slow());
     return Temporal_with_date::daynr();
   }
+  int weekday(bool sunday_first_day_of_week) const
+  {
+    DBUG_ASSERT(is_valid_datetime_slow());
+    return Temporal_with_date::weekday(sunday_first_day_of_week);
+  }
   ulong dayofyear() const
   {
     DBUG_ASSERT(is_valid_datetime_slow());
diff --git a/sql/threadpool_generic.cc b/sql/threadpool_generic.cc
index eb92846ed07..6f8e1982836 100644
--- a/sql/threadpool_generic.cc
+++ b/sql/threadpool_generic.cc
@@ -1322,7 +1322,7 @@ void wait_begin(thread_group_t *thread_group)
   DBUG_ASSERT(thread_group->connection_count > 0);
 
   if ((thread_group->active_thread_count == 0) && 
-     (is_queue_empty(thread_group) || !thread_group->listener))
+     (!is_queue_empty(thread_group) || !thread_group->listener))
   {
     /* 
       Group might stall while this thread waits, thus wake 
diff --git a/sql/tztime.cc b/sql/tztime.cc
index c45a6598d69..46a24a137e5 100644
--- a/sql/tztime.cc
+++ b/sql/tztime.cc
@@ -2432,7 +2432,7 @@ print_tz_leaps_as_sql(const TIME_ZONE_INFO *sp)
   if (!opt_skip_write_binlog)
       printf("\\d |\n"
         "IF (select count(*) from information_schema.global_variables where\n"
-        "variable_name='wsrep_on') = 1 THEN\n"
+        "variable_name='wsrep_on' and variable_value='ON') = 1 THEN\n"
         "ALTER TABLE time_zone_leap_second ENGINE=InnoDB;\n"
         "END IF|\n"
         "\\d ;\n");
@@ -2452,7 +2452,7 @@ print_tz_leaps_as_sql(const TIME_ZONE_INFO *sp)
   if (!opt_skip_write_binlog)
       printf("\\d |\n"
         "IF (select count(*) from information_schema.global_variables where\n"
-        "variable_name='wsrep_on') = 1 THEN\n"
+        "variable_name='wsrep_on' and variable_value='ON') = 1 THEN\n"
         "ALTER TABLE time_zone_leap_second ENGINE=Aria;\n"
         "END IF|\n"
         "\\d ;\n");
@@ -2709,7 +2709,7 @@ main(int argc, char **argv)
        sql_log_bin and wsrep_on to avoid Galera replicating below
        truncate table clauses. This will allow user to set different
        time zones to nodes in Galera cluster. */
-    printf("set @prep1=if((select count(*) from information_schema.global_variables where variable_name='wsrep_on'), 'SET SESSION SQL_LOG_BIN=?, WSREP_ON=OFF;', 'do ?');\n"
+    printf("set @prep1=if((select count(*) from information_schema.global_variables where variable_name='wsrep_on' and variable_value='ON'), 'SET SESSION SQL_LOG_BIN=?, WSREP_ON=OFF;', 'do ?');\n"
            "prepare set_wsrep_write_binlog from @prep1;\n"
            "set @toggle=0; execute set_wsrep_write_binlog using @toggle;\n");
 
@@ -2725,7 +2725,7 @@ main(int argc, char **argv)
       // to allow changes to them to replicate with Galera
       printf("\\d |\n"
         "IF (select count(*) from information_schema.global_variables where\n"
-        "variable_name='wsrep_on') = 1 THEN\n"
+        "variable_name='wsrep_on' and variable_value='ON') = 1 THEN\n"
         "ALTER TABLE time_zone ENGINE=InnoDB;\n"
         "ALTER TABLE time_zone_name ENGINE=InnoDB;\n"
         "ALTER TABLE time_zone_transition ENGINE=InnoDB;\n"
@@ -2780,7 +2780,7 @@ main(int argc, char **argv)
       // Fall back to Aria
       printf("\\d |\n"
         "IF (select count(*) from information_schema.global_variables where\n"
-        "variable_name='wsrep_on') = 1 THEN\n"
+        "variable_name='wsrep_on' and variable_value='ON') = 1 THEN\n"
         "ALTER TABLE time_zone ENGINE=Aria;\n"
         "ALTER TABLE time_zone_name ENGINE=Aria;\n"
         "ALTER TABLE time_zone_transition ENGINE=Aria;\n"
diff --git a/sql/unireg.cc b/sql/unireg.cc
index d019b5f8a75..a1605dac2e6 100644
--- a/sql/unireg.cc
+++ b/sql/unireg.cc
@@ -432,7 +432,8 @@ LEX_CUSTRING build_frm_image(THD *thd, const LEX_CSTRING &table,
   pos+= reclength;
   int2store(pos, create_info->connect_string.length);
   pos+= 2;
-  memcpy(pos, create_info->connect_string.str, create_info->connect_string.length);
+  if (create_info->connect_string.length)
+    memcpy(pos, create_info->connect_string.str, create_info->connect_string.length);
   pos+= create_info->connect_string.length;
   int2store(pos, str_db_type.length);
   pos+= 2;