Bug #16567 binlog_format option does not show when doing ./mysqd --help --verbose

  Implementing this feature connected to wl#3368 mixed binlog_format default.
  Supplied by my.cnf or explicitly in command line option gets be displayed.
  When not supplied `(No default value)' is displayed, even though --log-bin might
  be supplied. The option is different object from @@global.binlog_format variable.
  The default `mixed' for the latter is dependant on presence of `--log-bin' option,
  otherwise the value of the var is set to NULL (undefined):

   var := opt | MIXED  when binlog-in-use
   var := NULL         otherwise (no binlog, no format)

  Comments on NDB and mixed format updated, also dependency the option on --log-bin
  aka binlog-in-use is worded.
  
  Making t/rpl_switch_stm_row_mixed.test to interprete DEFAULT for binlog_format
  as MIXED.
  Comments on what the test covers are added.

  todo/fixme: turning @@global.binlog_format to be read-only when it's set to NULL (no binlog).
  todo/fixme: options dependacy (acyclic) graph, particularly to solve a task of
setting defaults values for the leaf nodes
  only when parents' nodes are set.

mysql-test/r/rpl_switch_stm_row_mixed.result

@@ -7,8 +7,31 @@ start slave;
 drop database if exists mysqltest1;
 create database mysqltest1;
 use mysqltest1;
+set session binlog_format=mixed;
+show session variables like "binlog_format%";
+Variable_name	Value
+binlog_format	MIXED
+set session binlog_format=statement;
+show session variables like "binlog_format%";
+Variable_name	Value
+binlog_format	STATEMENT
 set session binlog_format=row;
-set global binlog_format=row;
+show session variables like "binlog_format%";
+Variable_name	Value
+binlog_format	ROW
+set global binlog_format=DEFAULT;
+show global variables like "binlog_format%";
+Variable_name	Value
+binlog_format	MIXED
+set global binlog_format=MIXED;
+show global variables like "binlog_format%";
+Variable_name	Value
+binlog_format	MIXED
+set global binlog_format=STATEMENT;
+show global variables like "binlog_format%";
+Variable_name	Value
+binlog_format	STATEMENT
+set global binlog_format=ROW;
 show global variables like "binlog_format%";
 Variable_name	Value
 binlog_format	ROW
@@ -67,12 +90,11 @@ execute stmt1 using @string;
 deallocate prepare stmt1;
 insert into t1 values("for_10_");
 insert into t1 select "yesterday_11_";
-set binlog_format=default;
+set binlog_format=statement;
 select @@global.binlog_format, @@session.binlog_format;
 @@global.binlog_format	@@session.binlog_format
 STATEMENT	STATEMENT
-set global binlog_format=default;
-ERROR 42000: Variable 'binlog_format' doesn't have a default value
+set global binlog_format=statement;
 select @@global.binlog_format, @@session.binlog_format;
 @@global.binlog_format	@@session.binlog_format
 STATEMENT	STATEMENT
@@ -87,11 +109,11 @@ execute stmt1 using @string;
 deallocate prepare stmt1;
 insert into t1 values("for_15_");
 insert into t1 select "yesterday_16_";
-set binlog_format=mixed;
+set global binlog_format=mixed;
 select @@global.binlog_format, @@session.binlog_format;
 @@global.binlog_format	@@session.binlog_format
-STATEMENT	MIXED
-set global binlog_format=mixed;
+MIXED	STATEMENT
+set binlog_format=default;
 select @@global.binlog_format, @@session.binlog_format;
 @@global.binlog_format	@@session.binlog_format
 MIXED	MIXED

mysql-test/t/rpl_switch_stm_row_mixed.test

+#
+# rpl_switch_stm_row_mixed tests covers
+#
+#   - switching explicitly between STATEMENT, ROW, and MIXED binlog format
+#     showing when it is possible and when not. 
+#   - switching from MIXED to RBR implicitly listing all use cases,
+#     e.g a query invokes UUID(), thereafter to serve as the definition
+#     of MIXED binlog format
+#   - correctness of execution
+
+
 -- source include/not_ndb_default.inc
 -- source include/master-slave.inc
 
@@ -8,9 +19,22 @@ create database mysqltest1;
 --enable_warnings
 use mysqltest1;
 
+
+#  play with switching
+set session binlog_format=mixed;
+show session variables like "binlog_format%";
+set session binlog_format=statement;
+show session variables like "binlog_format%";
 set session binlog_format=row;
-set global binlog_format=row;
+show session variables like "binlog_format%";
 
+set global binlog_format=DEFAULT;
+show global variables like "binlog_format%";
+set global binlog_format=MIXED;
+show global variables like "binlog_format%";
+set global binlog_format=STATEMENT;
+show global variables like "binlog_format%";
+set global binlog_format=ROW;
 show global variables like "binlog_format%";
 show session variables like "binlog_format%";
 select @@global.binlog_format, @@session.binlog_format;
@@ -63,12 +87,10 @@ deallocate prepare stmt1;
 insert into t1 values("for_10_");
 insert into t1 select "yesterday_11_";
 
-# test SET DEFAULT (=statement at this point of test)
-set binlog_format=default;
+# test statement (is not default after wl#3368)
+set binlog_format=statement;
 select @@global.binlog_format, @@session.binlog_format;
-# due to cluster it's hard to set back to default
---error ER_NO_DEFAULT
-set global binlog_format=default;
+set global binlog_format=statement;
 select @@global.binlog_format, @@session.binlog_format;
 
 prepare stmt1 from 'insert into t1 select ?';
@@ -87,10 +109,10 @@ insert into t1 select "yesterday_16_";
 
 # and now the mixed mode
 
-set binlog_format=mixed;
-select @@global.binlog_format, @@session.binlog_format;
 set global binlog_format=mixed;
 select @@global.binlog_format, @@session.binlog_format;
+set binlog_format=default;
+select @@global.binlog_format, @@session.binlog_format;
 
 prepare stmt1 from 'insert into t1 select concat(UUID(),?)';
 set @string="emergency_17_";

sql/mysqld.cc

@@ -444,9 +444,10 @@ my_bool sp_automatic_privileges= 1;
 ulong opt_binlog_rows_event_max_size;
 const char *binlog_format_names[]= {"STATEMENT", "ROW", "MIXED", NullS};
 TYPELIB binlog_format_typelib=
-  { array_elements(binlog_format_names)-1,"",
+  { array_elements(binlog_format_names) - 1, "",
     binlog_format_names, NULL };
-
+ulong opt_binlog_format_id= (ulong) BINLOG_FORMAT_UNSPEC;
+const char *opt_binlog_format= binlog_format_names[opt_binlog_format_id];
 #ifdef HAVE_INITGROUPS
 static bool calling_initgroups= FALSE; /* Used in SIGSEGV handler. */
 #endif
@@ -3148,17 +3149,24 @@ with --log-bin instead.");
                     "--log-slave-updates work.");
     unireg_abort(1);
   }
-
- if (!opt_bin_log && (global_system_variables.binlog_format != BINLOG_FORMAT_UNSPEC))
-  {
-    sql_print_error("You need to use --log-bin to make "
-                    "--binlog-format work.");
-    unireg_abort(1);
-  }
-  if (global_system_variables.binlog_format == BINLOG_FORMAT_UNSPEC)
-  {
+  if (!opt_bin_log)
+    if (opt_binlog_format_id != BINLOG_FORMAT_UNSPEC)
+    {
+      sql_print_error("You need to use --log-bin to make "
+		      "--binlog-format work.");
+      unireg_abort(1);
+    }
+    else
+    {
+      global_system_variables.binlog_format= BINLOG_FORMAT_UNSPEC;
+    }
+  else
+    if (opt_binlog_format_id == BINLOG_FORMAT_UNSPEC)
       global_system_variables.binlog_format= BINLOG_FORMAT_MIXED;
-  }
+    else
+    { 
+      DBUG_ASSERT(global_system_variables.binlog_format != BINLOG_FORMAT_UNSPEC);
+    }
 
   /* Check that we have not let the format to unspecified at this point */
   DBUG_ASSERT((uint)global_system_variables.binlog_format <=
@@ -4905,6 +4913,7 @@ struct my_option my_long_options[] =
    (gptr*) &my_bind_addr_str, (gptr*) &my_bind_addr_str, 0, GET_STR,
    REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"binlog_format", OPT_BINLOG_FORMAT,
+   "Does not have any effect without '--log-bin'. "
    "Tell the master the form of binary logging to use: either 'row' for "
    "row-based binary logging, or 'statement' for statement-based binary "
    "logging, or 'mixed'. 'mixed' is statement-based binary logging except "
@@ -4912,11 +4921,12 @@ struct my_option my_long_options[] =
    "involve user-defined functions (i.e. UDFs) or the UUID() function; for "
    "those, row-based binary logging is automatically used. "
 #ifdef HAVE_NDB_BINLOG
-   "If ndbcluster is enabled, the default is 'row'."
+   "If ndbcluster is enabled and binlog_format is `mixed', the format switches"
+   " to 'row' and back implicitly per each query accessing a NDB table."
 #endif
-   , 0, 0, 0, GET_STR, REQUIRED_ARG,
-   BINLOG_FORMAT_MIXED
-   , 0, 0, 0, 0, 0 },
+   ,(gptr*) &opt_binlog_format, (gptr*) &opt_binlog_format,
+   0, GET_STR, REQUIRED_ARG, BINLOG_FORMAT_MIXED, BINLOG_FORMAT_STMT,
+   BINLOG_FORMAT_MIXED, 0, 0, 0},
   {"binlog-do-db", OPT_BINLOG_DO_DB,
    "Tells the master it should log updates for the specified database, and exclude all others not explicitly mentioned.",
    0, 0, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
@@ -7267,7 +7277,7 @@ get_one_option(int optid, const struct my_option *opt __attribute__((unused)),
               binlog_format_names[BINLOG_FORMAT_MIXED]);
       exit(1);
     }
-    global_system_variables.binlog_format= id-1;
+    global_system_variables.binlog_format= opt_binlog_format_id= id - 1;
     break;
   }
   case (int)OPT_BINLOG_DO_DB: