This will be pushed only after I fix the testsuite.

This is the main commit for Worklog tasks:
 * A more dynamic binlog format which allows small changes (1064)
 * Log session variables in Query_log_event (1063)
Below 5.0 means 5.0.0.
MySQL 5.0 is able to replicate FOREIGN_KEY_CHECKS, UNIQUE_KEY_CHECKS (for speed),
SQL_AUTO_IS_NULL, SQL_MODE. Not charsets (WL#1062), not some vars (I can only think
of SQL_SELECT_LIMIT, which deserves a special treatment). Note that this
works for queries, except LOAD DATA INFILE (for this it would have to wait
for Dmitri's push of WL#874, which in turns waits for the present push, so...
the deadlock must be broken!). Note that when Dmitri pushes WL#874 in 5.0.1,
5.0.0 won't be able to replicate a LOAD DATA INFILE from 5.0.1.
Apart from that, the new binlog format is designed so that it can tolerate
a little variation in the events (so that a 5.0.0 slave could replicate a
5.0.1 master, except for LOAD DATA INFILE unfortunately); that is, when I
later add replication of charsets it should break nothing. And when I later
add a UID to every event, it should break nothing.
The main change brought by this patch is a new type of event, Format_description_log_event,
which describes some lengthes in other event types. This event is needed for
the master/slave/mysqlbinlog to understand a 5.0 log. Thanks to this event,
we can later add more bytes to the header of every event without breaking compatibility.
Inside Query_log_event, we have some additional dynamic format, as every Query_log_event
can have a different number of status variables, stored as pairs (code, value); that's
how SQL_MODE and session variables and catalog are stored. Like this, we can later
add count of affected rows, charsets... and we can have options --don't-log-count-affected-rows
if we want.
MySQL 5.0 is able to run on 4.x relay logs, 4.x binlogs.
Upgrading a 4.x master to 5.0 is ok (no need to delete binlogs),
upgrading a 4.x slave to 5.0 is ok (no need to delete relay logs);
so both can be "hot" upgrades.
Upgrading a 3.23 master to 5.0 requires as much as upgrading it to 4.0.
3.23 and 4.x can't be slaves of 5.0.
So downgrading from 5.0 to 4.x may be complicated.
Log_event::log_pos is now the position of the end of the event, which is
more useful than the position of the beginning. We take care about compatibility
with <5.0 (in which log_pos is the beginning).
I added a short test for replication of SQL_MODE and some other variables.
TODO:
- after committing this, merge the latest 5.0 into it
- fix all tests
- update the manual with upgrade notes.


client/Makefile.am:
  mysqlbinlog.cc depends slightly on sql/mysql_priv.h
client/mysqlbinlog.cc:
  Make mysqlbinlog able to read the new binlog format,
  by seeking to the start and reading the first few events, to
  detect the format of the binlog.
include/my_sys.h:
  a correct tell() for SEQ_READ_APPEND caches.
mysys/mf_iocache2.c:
  a correct tell() for SEQ_READ_APPEND caches
  (my_b_tell() is not working for such caches).
sql/ha_innodb.cc:
  we are getting rid of event lengthes here and there, which is good.
sql/log.cc:
  Start events will have created==0 if generated by rotation (like in 3.23).
  In 5.0 we always write a Format_description_log_event at the beginning of
  every master's binary log and of every slave's relay log.
  We also add Rotate and Stop to relay logs (like there already was in
  master's binary logs).
  When we rotate a relay log, we write the previous relay log's Start event
  (the one which was sent from the master) to the beginning of the new log,
  so that we don't need the previous relay log to understand the new one;
  that's the purpose of MYSQL_LOG::description_event_for_queue.
  Removed logging of SET FOREIGN_KEY_CHECKS, because we handle it as flags
  in the Query event now.
sql/log_event.cc:
  New event type: Format_description_log_event, to describe the log's format.
  read_log_event() needs to be passed this event to be able to read 5.0 events.
  Query_log_event has new members flags2 and sql_mode for replication of session
  variables (except charsets which are WL#1062) and SQL_MODE.
  flags2 is in fact a kind of copy of thd->options (&'d with a mask).
  Now with this replication of FOREIGN_KEY_CHECKS, SQL_AUTO_IS_NULL, UNIQUE_CHECKS
  and SQL_MODE work; with mysqlbinlog too.
sql/log_event.h:
  Binlog version is changed to 4.
  New classes (details in sql/log_event.cc).
  Removing some useless #defines.
sql/mysql_priv.h:
  Definition of SELECT_DISTINCT and others must be visible in client/mysqlbinlog.cc,
  so adding #ifdefs.
sql/mysqld.cc:
  update for prototype change
sql/slave.cc:
  When the slave opens a relay log, it reads the first few events to know the format.
  When slave I/O thread receives a Rotate from the master, it rotates its relay log
  (to avoid mixed format in the relay log).
sql/slave.h:
  in the slave we avoid lengthes and rely on absolute positions instead;
  hence the introduction of future_group_master_log_pos and future_event_relay_log_pos
  (explained in code).
sql/sql_class.cc:
  catalog in THD
sql/sql_class.h:
  catalog, and new members in MYSQL_LOG
sql/sql_repl.cc:
  When the master starts sending binlog to slave, it must
  first read the first few events to detect the binlog's format.
  Same for SHOW BINLOG EVENTS.

client/Makefile.am

@@ -39,7 +39,7 @@ mysqlbinlog_SOURCES =   mysqlbinlog.cc ../mysys/mf_tempdir.c
 mysqlbinlog_DEPENDENCIES=   	$(LIBRARIES) $(pkglib_LTLIBRARIES)
 mysqlmanagerc_SOURCES =   mysqlmanagerc.c 
 mysqlmanagerc_DEPENDENCIES=   	$(LIBRARIES) $(pkglib_LTLIBRARIES)
-sql_src=log_event.h log_event.cc
+sql_src=log_event.h mysql_priv.h log_event.cc
 
 # Fix for mit-threads
 DEFS =			-DUNDEF_THREADS_HACK

include/my_sys.h

@@ -498,6 +498,7 @@ typedef int (*qsort2_cmp)(const void *, const void *, const void *);
 
 /* tell write offset in the SEQ_APPEND cache */
 my_off_t my_b_append_tell(IO_CACHE* info);
+my_off_t my_b_safe_tell(IO_CACHE* info); /* picks the correct tell() */
 
 #define my_b_bytes_in_cache(info) (uint) (*(info)->current_end - \
 					  *(info)->current_pos)

mysql-test/r/rpl_session_var.result

+stop slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+reset master;
+reset slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+start slave;
+drop table if exists t1;
+Warnings:
+Note	1051	Unknown table 't1'
+create table t1(a varchar(10),b int);
+set @@session.sql_mode=pipes_as_concat;
+insert into t1 values('My'||'SQL', 1);
+set @@session.sql_mode=default;
+insert into t1 values('My'||'SQL', 2);
+select * from t1 where b<3 order by a;
+a	b
+0	2
+MySQL	1
+select * from t1 where b<3 order by a;
+a	b
+0	2
+MySQL	1
+set @@session.sql_mode=ignore_space;
+insert into t1 values(password          ('MySQL'), 3);
+set @@session.sql_mode=ansi_quotes;
+create table "t2" ("a" int);
+drop table t1, t2;
+set @@session.sql_mode=default;
+create table t1(a int auto_increment primary key);
+create table t2(b int, a int);
+set @@session.sql_auto_is_null=1;
+insert into t1 values(null);
+insert into t2 select 1,a from t1 where a is null;
+set @@session.sql_auto_is_null=0;
+insert into t1 values(null);
+insert into t2 select 2,a from t1 where a is null;
+select * from t2 order by b;
+b	a
+1	1
+select * from t2 order by b;
+b	a
+1	1
+drop table t1,t2;

mysql-test/t/rpl_session_var.test

+# Replication of session variables.
+# FOREIGN_KEY_CHECKS is tested in rpl_insert_id.test
+
+source include/master-slave.inc;
+drop table if exists t1;
+create table t1(a varchar(10),b int);
+set @@session.sql_mode=pipes_as_concat;
+insert into t1 values('My'||'SQL', 1);
+set @@session.sql_mode=default;
+insert into t1 values('My'||'SQL', 2);
+select * from t1 where b<3 order by a;
+save_master_pos;
+connection slave;
+sync_with_master;
+select * from t1 where b<3 order by a;
+connection master;
+# if the slave does the next sync_with_master fine, then it means it accepts the
+# two lines of ANSI syntax below, which is what we want to check.
+set @@session.sql_mode=ignore_space;
+insert into t1 values(password          ('MySQL'), 3);
+set @@session.sql_mode=ansi_quotes;
+create table "t2" ("a" int);
+drop table t1, t2;
+set @@session.sql_mode=default;
+create table t1(a int auto_increment primary key);
+create table t2(b int, a int);
+set @@session.sql_auto_is_null=1;
+insert into t1 values(null);
+insert into t2 select 1,a from t1 where a is null;
+set @@session.sql_auto_is_null=0;
+insert into t1 values(null);
+insert into t2 select 2,a from t1 where a is null;
+select * from t2 order by b;
+save_master_pos;
+connection slave;
+sync_with_master;
+select * from t2 order by b;
+connection master;
+drop table t1,t2;
+save_master_pos;
+connection slave;
+sync_with_master;

mysys/mf_iocache2.c

@@ -66,6 +66,13 @@ my_off_t my_b_append_tell(IO_CACHE* info)
   return res;
 }
 
+my_off_t my_b_safe_tell(IO_CACHE *info)
+{
+  if (unlikely(info->type == SEQ_READ_APPEND))
+    return my_b_append_tell(info);
+  return my_b_tell(info);
+}
+
 /*
   Make next read happen at the given position
   For write cache, make next write happen at the given position

sql/ha_innodb.cc

@@ -987,10 +987,19 @@ innobase_commit_low(
 
                 trx->mysql_master_log_file_name
                                         = active_mi->rli.group_master_log_name;
+                /*
+                  Guilhem to Heikki: in 5.0 we don't need to do a computation
+                  (old_pos+len) to get the end_pos, because we already have the
+                  end_pos under hand in the replication code
+                  (Query_log_event::exec_event()).
+                  I tested the code change below (simulated a crash with kill
+                  -9) and got the good (binlog, position) displayed by InnoDB at
+                  crash recovery, so this code change is ok.
+                */
                 trx->mysql_master_log_pos = ((ib_longlong)
-                                         (active_mi->rli.group_master_log_pos +
-                                          active_mi->rli.event_len
-                                          ));
+                                             (active_mi->rli.future_group_master_log_pos 
+                                              ));
+                
         }
 #endif /* HAVE_REPLICATION */
 

sql/log.cc

@@ -84,7 +84,8 @@ static int find_uniq_filename(char *name)
 MYSQL_LOG::MYSQL_LOG()
   :bytes_written(0), last_time(0), query_start(0), name(0),
    file_id(1), open_count(1), log_type(LOG_CLOSED), write_error(0), inited(0),
-   need_start_event(1)
+   need_start_event(1), description_event_for_exec(0),
+   description_event_for_queue(0)
 {
   /*
     We don't want to initialize LOCK_Log here as such initialization depends on
@@ -111,6 +112,8 @@ void MYSQL_LOG::cleanup()
   {
     inited= 0;
     close(LOG_CLOSE_INDEX);
+    delete description_event_for_queue;
+    delete description_event_for_exec;
     (void) pthread_mutex_destroy(&LOCK_log);
     (void) pthread_mutex_destroy(&LOCK_index);
     (void) pthread_cond_destroy(&update_cond);
@@ -179,7 +182,8 @@ bool MYSQL_LOG::open(const char *log_name, enum_log_type log_type_arg,
 		     const char *new_name, const char *index_file_name_arg,
 		     enum cache_type io_cache_type_arg,
 		     bool no_auto_events_arg,
-                     ulong max_size_arg)
+                     ulong max_size_arg,
+                     bool null_created_arg)
 {
   char buff[512];
   File file= -1, index_file_nr= -1;
@@ -272,8 +276,8 @@ bool MYSQL_LOG::open(const char *log_name, enum_log_type log_type_arg,
       if (my_b_safe_write(&log_file, (byte*) BINLOG_MAGIC,
 			  BIN_LOG_HEADER_SIZE))
         goto err;
-      bytes_written += BIN_LOG_HEADER_SIZE;
-      write_file_name_to_index_file=1;
+      bytes_written+= BIN_LOG_HEADER_SIZE;
+      write_file_name_to_index_file= 1;
     }
 
     if (!my_b_inited(&index_file))
@@ -302,10 +306,42 @@ bool MYSQL_LOG::open(const char *log_name, enum_log_type log_type_arg,
     }
     if (need_start_event && !no_auto_events)
     {
-      need_start_event=0;
-      Start_log_event s;
+      /*
+        In 4.x we set need_start_event=0 here, but in 5.0 we want a Start event
+        even if this is not the very first binlog.
+      */
+      Format_description_log_event s(BINLOG_VERSION);
+      if (!s.is_valid())
+        goto err;
       s.set_log_pos(this);
-      s.write(&log_file);
+      if (null_created_arg)
+        s.created= 0;
+      if (s.write(&log_file))
+        goto err;
+      bytes_written+= s.get_event_len();
+    }
+    if (description_event_for_queue &&
+        description_event_for_queue->binlog_version>=4)
+    {
+      /*
+        This is a relay log written to by the I/O slave thread.
+        Write the event so that others can later know the format of this relay
+        log.
+        Note that this event is very close to the original event from the
+        master (it has binlog version of the master, event types of the
+        master), so this is suitable to parse the next relay log's event. It
+        has been produced by
+        Format_description_log_event::Format_description_log_event(char*
+        buf,).
+        Why don't we want to write the description_event_for_queue if this event
+        is for format<4 (3.23 or 4.x): this is because in that case, the
+        description_event_for_queue describes the data received from the master,
+        but not the data written to the relay log (*conversion*), which is in
+        format 4 (slave's).
+      */
+      if (description_event_for_queue->write(&log_file))
+        goto err;
+      bytes_written+= description_event_for_queue->get_event_len();
     }
     if (flush_io_cache(&log_file))
       goto err;
@@ -596,7 +632,7 @@ bool MYSQL_LOG::reset_logs(THD* thd)
   if (!thd->slave_thread)
     need_start_event=1;
   open(save_name, save_log_type, 0, index_file_name,
-       io_cache_type, no_auto_events, max_size);
+       io_cache_type, no_auto_events, max_size, 0);
   my_free((gptr) save_name, MYF(0));
 
 err:  
@@ -986,8 +1022,17 @@ void MYSQL_LOG::new_file(bool need_lock)
      Note that at this point, log_type != LOG_CLOSED (important for is_open()).
   */
 
+  /* 
+     new_file() is only used for rotation (in FLUSH LOGS or because size >
+     max_binlog_size or max_relay_log_size). 
+     If this is a binary log, the Format_description_log_event at the beginning of
+     the new file should have created=0 (to distinguish with the
+     Format_description_log_event written at server startup, which should
+     trigger temp tables deletion on slaves.
+  */ 
+
   open(old_name, save_log_type, new_name_ptr, index_file_name, io_cache_type,
-       no_auto_events, max_size);
+       no_auto_events, max_size, 1);
   my_free(old_name,MYF(0));
 
 end:
@@ -1282,6 +1327,12 @@ bool MYSQL_LOG::write(Log_event* event_info)
       }
 #endif
 
+#if MYSQL_VERSION_ID < 50000
+      /*
+        In 5.0 this is not needed anymore as we store the value of
+        FOREIGN_KEY_CHECKS in a binary way in the Query event's header.
+        The code below was enabled in 4.0 and 4.1.
+      */
       /*
 	If the user has set FOREIGN_KEY_CHECKS=0 we wrap every SQL
 	command in the binlog inside:
@@ -1297,6 +1348,7 @@ bool MYSQL_LOG::write(Log_event* event_info)
 	if (e.write(file))
 	  goto err;
       }
+#endif
     }
 
     /* Write the SQL command */
@@ -1307,6 +1359,7 @@ bool MYSQL_LOG::write(Log_event* event_info)
 
     /* Write log events to reset the 'run environment' of the SQL command */
 
+#if MYSQL_VERSION_ID < 50000
     if (thd && thd->options & OPTION_NO_FOREIGN_KEY_CHECKS)
     {
       Query_log_event e(thd, "SET FOREIGN_KEY_CHECKS=1", 24, 0);
@@ -1314,6 +1367,7 @@ bool MYSQL_LOG::write(Log_event* event_info)
       if (e.write(file))
 	goto err;
     }
+#endif
 
     /*
       Tell for transactional table handlers up to which position in the
@@ -1720,6 +1774,7 @@ void MYSQL_LOG::close(uint exiting)
       Stop_log_event s;
       s.set_log_pos(this);
       s.write(&log_file);
+      bytes_written+= s.get_event_len();
       signal_update();
     }
 #endif /* HAVE_REPLICATION */

sql/mysql_priv.h

@@ -14,6 +14,15 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
+/*
+  Mostly this file is used in the server. But a little part of it is used in
+  mysqlbinlog too (definition of SELECT_DISTINCT and others).
+  The consequence is that 90% of the file is wrapped in #ifndef MYSQL_CLIENT,
+  except the part which must be in the server and in the client.
+*/
+
+#ifndef MYSQL_CLIENT
+
 #include <my_global.h>
 #include <assert.h>
 #include <mysql_version.h>
@@ -176,7 +185,15 @@ extern CHARSET_INFO *national_charset_info, *table_alias_charset;
 #define TEST_NO_STACKTRACE	512
 #define TEST_SIGINT		1024	/* Allow sigint on threads */
 
-/* options for select set by the yacc parser (stored in lex->options) */
+#endif
+
+/* 
+   This is included in the server and in the client.
+   Options for select set by the yacc parser (stored in lex->options).
+   None of the 32 defines below should have its value changed, or this will
+   break replication.
+*/
+
 #define SELECT_DISTINCT		(1L << 0)
 #define SELECT_STRAIGHT_JOIN	(1L << 1)
 #define SELECT_DESCRIBE		(1L << 2)
@@ -214,6 +231,9 @@ extern CHARSET_INFO *national_charset_info, *table_alias_charset;
 #define OPTION_RELAXED_UNIQUE_CHECKS    (1L << 27)
 #define SELECT_NO_UNLOCK                (1L << 28)
 
+/* The rest of the file is included in the server only */
+#ifndef MYSQL_CLIENT
+
 /* options for UNION set by the yacc parser (stored in unit->union_option) */
 #define UNION_ALL               1
 
@@ -1102,3 +1122,5 @@ inline void setup_table_map(TABLE *table, TABLE_LIST *table_list, uint tablenr)
   table->map= (table_map) 1 << tablenr;
   table->force_index= table_list->force_index;
 }
+
+#endif /* MYSQL_CLIENT */

sql/mysqld.cc

@@ -2023,7 +2023,7 @@ bool open_log(MYSQL_LOG *log, const char *hostname,
   }
   return log->open(opt_name, type, 0, index_file_name,
 		   (read_append) ? SEQ_READ_APPEND : WRITE_CACHE,
-		   no_auto_events, max_size);
+		   no_auto_events, max_size, 0);
 }
 
 

sql/slave.h

@@ -67,11 +67,6 @@ extern my_bool opt_log_slave_updates;
 extern ulonglong relay_log_space_limit;
 struct st_master_info;
 
-enum enum_binlog_formats {
-  BINLOG_FORMAT_CURRENT=0, /* 0 is important for easy 'if (mi->old_format)' */
-  BINLOG_FORMAT_323_LESS_57, 
-  BINLOG_FORMAT_323_GEQ_57 };
-
 /*
   TODO: this needs to be redone, but for now it does not matter since
   we do not have multi-master yet.
@@ -186,6 +181,8 @@ typedef struct st_relay_log_info
   ulonglong group_relay_log_pos;
   char event_relay_log_name[FN_REFLEN];
   ulonglong event_relay_log_pos;
+  ulonglong future_event_relay_log_pos;
+
   /* 
      Original log name and position of the group we're currently executing
      (whose coordinates are group_relay_log_name/pos in the relay log)
@@ -207,11 +204,13 @@ typedef struct st_relay_log_info
 
   /*
     InnoDB internally stores the master log position it has processed
-    so far; the position to store is really the sum of 
-    pos + pending + event_len here since we must store the pos of the
-    END of the current log event
+    so far; when the InnoDB code to store this position is called, we have not
+    updated rli->group_master_log_pos yet. So the position is the event's
+    log_pos (the position of the end of the event); we save it in the variable
+    below. It's the *coming* group_master_log_pos (the one which will be
+    group_master_log_pos in the coming milliseconds).
   */
-  int event_len;
+  ulonglong future_group_master_log_pos;
 
   time_t last_master_timestamp; 
 
@@ -285,16 +284,17 @@ typedef struct st_relay_log_info
       until_log_names_cmp_result= UNTIL_LOG_NAMES_CMP_UNKNOWN;
   }
   
-  inline void inc_event_relay_log_pos(ulonglong val)
+  inline void inc_event_relay_log_pos()
   {
-    event_relay_log_pos+= val;
+    event_relay_log_pos= future_event_relay_log_pos;
   }
 
-  void inc_group_relay_log_pos(ulonglong val, ulonglong log_pos, bool skip_lock=0)
+  void inc_group_relay_log_pos(ulonglong log_pos,
+                               bool skip_lock=0)  
   {
     if (!skip_lock)
       pthread_mutex_lock(&data_lock);
-    inc_event_relay_log_pos(val);
+    inc_event_relay_log_pos();
     group_relay_log_pos= event_relay_log_pos;
     strmake(group_relay_log_name,event_relay_log_name,
             sizeof(group_relay_log_name)-1);
@@ -311,8 +311,31 @@ typedef struct st_relay_log_info
       not advance as it should on the non-transactional slave (it advances by
       big leaps, whereas it should advance by small leaps).
     */
-    if (log_pos) // 3.23 binlogs don't have log_posx
-      group_master_log_pos= log_pos+ val;
+    /*
+      In 4.x we used the event's len to compute the positions here. This is
+      wrong if the event was 3.23/4.0 and has been converted to 5.0, because
+      then the event's len is not what is was in the master's binlog, so this
+      will make a wrong group_master_log_pos (yes it's a bug in 3.23->4.0
+      replication: Exec_master_log_pos is wrong). Only way to solve this is to
+      have the original offset of the end of the event the relay log. This is
+      what we do in 5.0: log_pos has become "end_log_pos" (because the real use
+      of log_pos in 4.0 was to compute the end_log_pos; so better to store
+      end_log_pos instead of begin_log_pos.
+      If we had not done this fix here, the problem would also have appeared
+      when the slave and master are 5.0 but with different event length (for
+      example the slave is more recent than the master and features the event
+      UID). It would give false MASTER_POS_WAIT, false Exec_master_log_pos in
+      SHOW SLAVE STATUS, and so the user would do some CHANGE MASTER using this
+      value which would lead to badly broken replication.
+      Even the relay_log_pos will be corrupted in this case, because the len is
+      the relay log is not "val".
+      With the end_log_pos solution, we avoid computations involving lengthes.
+    */
+    DBUG_PRINT("info", ("log_pos=%lld group_master_log_pos=%lld",
+                        log_pos,group_master_log_pos));
+    if (log_pos) // some events (like fake Rotate) don't have log_pos
+      // when we are here, log_pos is the end of the event
+      group_master_log_pos= log_pos;
     pthread_cond_broadcast(&data_cond);
     if (!skip_lock)
       pthread_mutex_unlock(&data_lock);
@@ -389,7 +412,6 @@ typedef struct st_master_info
   int events_till_abort;
 #endif
   bool inited;
-  enum enum_binlog_formats old_format;
   volatile bool abort_slave, slave_running;
   volatile ulong slave_run_id;
   /* 
@@ -404,7 +426,7 @@ typedef struct st_master_info
   long clock_diff_with_master; 
   
   st_master_info()
-    :ssl(0), fd(-1),  io_thd(0), inited(0), old_format(BINLOG_FORMAT_CURRENT),
+    :ssl(0), fd(-1),  io_thd(0), inited(0),
      abort_slave(0),slave_running(0), slave_run_id(0)
   {
     host[0] = 0; user[0] = 0; password[0] = 0;
@@ -535,10 +557,12 @@ void lock_slave_threads(MASTER_INFO* mi);
 void unlock_slave_threads(MASTER_INFO* mi);
 void init_thread_mask(int* mask,MASTER_INFO* mi,bool inverse);
 int init_relay_log_pos(RELAY_LOG_INFO* rli,const char* log,ulonglong pos,
-		       bool need_data_lock, const char** errmsg);
+		       bool need_data_lock, const char** errmsg,
+                       bool look_for_description_event);
 
 int purge_relay_logs(RELAY_LOG_INFO* rli, THD *thd, bool just_reset,
 		     const char** errmsg);
+void set_slave_thread_options(THD* thd);
 void rotate_relay_log(MASTER_INFO* mi);
 
 extern "C" pthread_handler_decl(handle_slave_io,arg);

sql/sql_class.cc

@@ -92,6 +92,7 @@ THD::THD():user_time(0), is_fatal_error(0),
 	   global_read_lock(0), bootstrap(0), spcont(NULL)
 {
   host= user= priv_user= db= ip= 0;
+  catalog= (char*)"std"; // the only catalog we have for now
   host_or_ip= "connecting host";
   locked=some_tables_deleted=no_errors=password= 0;
   query_start_used= 0;

sql/sql_class.h

@@ -26,6 +26,7 @@
 class Query_log_event;
 class Load_log_event;
 class Slave_log_event;
+class Format_description_log_event;
 class sp_rcontext;
 class sp_cache;
 
@@ -99,7 +100,14 @@ class MYSQL_LOG
   enum cache_type io_cache_type;
   bool write_error, inited;
   bool need_start_event;
-  bool no_auto_events;				// For relay binlog
+  /*
+    no_auto_events means we don't want any of these automatic events :
+    Start/Rotate/Stop. That is, in 4.x when we rotate a relay log, we don't want
+    a Rotate_log event to be written to the relay log. When we start a relay log
+    etc. So in 4.x this is 1 for relay logs, 0 for binlogs.
+    In 5.0 it's 0 for relay logs too!
+  */
+  bool no_auto_events;			     
   /* 
      The max size before rotation (usable only if log_type == LOG_BIN: binary
      logs and relay logs).
@@ -116,6 +124,18 @@ class MYSQL_LOG
 public:
   MYSQL_LOG();
   ~MYSQL_LOG();
+
+  /* 
+     These describe the log's format. This is used only for relay logs.
+     _for_exec is used by the SQL thread, _for_queue by the I/O thread. It's
+     necessary to have 2 distinct objects, because the I/O thread may be reading
+     events in a different format from what the SQL thread is reading (consider
+     the case of a master which has been upgraded from 5.0 to 5.1 without doing
+     RESET MASTER, or from 4.x to 5.0).
+  */
+  Format_description_log_event *description_event_for_exec,
+    *description_event_for_queue;
+
   void reset_bytes_written()
   {
     bytes_written = 0;
@@ -144,7 +164,8 @@ class MYSQL_LOG
   bool open(const char *log_name,enum_log_type log_type,
 	    const char *new_name, const char *index_file_name_arg,
 	    enum cache_type io_cache_type_arg,
-	    bool no_auto_events_arg, ulong max_size);
+	    bool no_auto_events_arg, ulong max_size,
+            bool null_created);
   void new_file(bool need_lock= 1);
   bool write(THD *thd, enum enum_server_command command,
 	     const char *format,...);
@@ -590,9 +611,10 @@ class THD :public ilink,
      the connection
     priv_user - The user privilege we are using. May be '' for anonymous user.
     db - currently selected database
+    catalog - currently selected catalog
     ip - client IP
    */
-  char	  *host,*user,*priv_user,*db,*ip;
+  char	  *host,*user,*priv_user,*db,*catalog,*ip;
   char	  priv_host[MAX_HOSTNAME];
   /* remote (peer) port */
   uint16 peer_port;