Implementation of WL#1824 "Add replication of character set variables in 4.1",

by binlogging some SET ONE_SHOT CHARACTER_SETetc,
which will be enough until we have it more compact and more complete in 5.0. With the present patch,
replication will work ok between 4.1.3 master and slaves, as long as:
- master and slave have the same GLOBAL.COLLATION_SERVER
- COLLATION_DATABASE and CHARACTER_SET_DATABASE are not used
- application does not use the fact that table is created with charset of the USEd db (BUG#2326).
all of which are not too hard to fulfill. 
ONE_SHOT is reserved for internal use of mysqlbinlog|mysql and works only for charsets,
so we give error if used for non-charset vars.
Fix for BUG#3875 "mysqlbinlog produces wrong ouput  if query uses
 variables containing quotes" and BUG#3943 "Queries with non-ASCII literals are not replicated
 properly after SET NAMES".
Detecting that master and slave have different global charsets or server ids.


mysql-test/r/rpl_server_id1.result:
  it's normal to not run as I have added a test to compare server ids of master and slave
  at startup and stop if equal (unless --replicate-same-server-id)
mysql-test/r/rpl_user_variables.result:
  result update (as we now print charset of user var).
mysql-test/r/user_var.result:
  result update
mysql-test/t/rpl_server_id1.test:
  no need to select as slave is not running
mysql-test/t/user_var.test:
  testing if the content of user vars is escaped when mysqlbinlog prints them,
  and if the name is backquoted.
sql/lex.h:
  new keyword ONE_SHOT
sql/log.cc:
  when writing to the binlog, before writing the actual statement, write some SET ONE_SHOT CHARACTER_SET_CLIENT etc
  for the slave to know the charset variables (which are important as they affect the inserted data).
sql/log_event.cc:
  print charset and collation of user var in mysqlbinlog and SHOW BINLOG EVENTS.
  escape the content of the var. Backquote its name.
  Will ask Bar to check that using my_charset_bin for escaping is ok.
sql/set_var.cc:
  understand SET CHARACTER_SET_CLIENT=10 (don't require a string, accept a number).
  Refuse changing of GLOBAL CHARACTER_SET_SERVER/COLLATION_SERVER if binlog or slave,
  as it will make the master or slave make wrong assumptions.
  A function to catch SET ONE_SHOT on non-charset variables (which is forbidden)
sql/set_var.h:
  no_support_one_shot to know if the var supports ONE_SHOT (only charset vars do, soon timezones).
  Accept int arg in SET CHARACTER_SET_etc
sql/slave.cc:
  when I/O slave thread starts, verify that master's and slave charsets match.
  And by the way verify that server ids are different.
  Don't fail if UNIX_TIMESTAMP() can't be done on master (very old master), that's
  not fatal.
sql/sql_class.cc:
  one_shot
sql/sql_class.h:
  one_shot
sql/sql_lex.h:
  one_shot
sql/sql_parse.cc:
  when SET ONE_SHOT is used, verify that it's only used for charset/collation vars;
  otherwise refuse.
sql/sql_yacc.yy:
  ONE_SHOT keyword in SET

18 files changed, 766 insertions, 84 deletions

diff --git a/mysql-test/r/rpl_charset.result b/mysql-test/r/rpl_charset.result
new file mode 100644
index 00000000000..6ba82d0dd2f
--- /dev/null
+++ b/mysql-test/r/rpl_charset.result
@@ -0,0 +1,199 @@
+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 database if exists test2;
+drop database if exists test3;
+create database test2 character set latin2;
+set @@character_set_server=latin5;
+create database test3;
+
+--- --master--
+show create database test2;
+Database	Create Database
+test2	CREATE DATABASE `test2` /*!40100 DEFAULT CHARACTER SET latin2 */
+show create database test3;
+Database	Create Database
+test3	CREATE DATABASE `test3` /*!40100 DEFAULT CHARACTER SET latin5 */
+
+--- --slave--
+show create database test2;
+Database	Create Database
+test2	CREATE DATABASE `test2` /*!40100 DEFAULT CHARACTER SET latin2 */
+show create database test3;
+Database	Create Database
+test3	CREATE DATABASE `test3` /*!40100 DEFAULT CHARACTER SET latin5 */
+set @@collation_server=armscii_bin;
+drop database test3;
+create database test3;
+
+--- --master--
+show create database test3;
+Database	Create Database
+test3	CREATE DATABASE `test3` /*!40100 DEFAULT CHARACTER SET armscii8 COLLATE armscii_bin */
+
+--- --slave--
+show create database test3;
+Database	Create Database
+test3	CREATE DATABASE `test3` /*!40100 DEFAULT CHARACTER SET armscii8 COLLATE armscii_bin */
+use test2;
+create table t1 (a int auto_increment primary key, b varchar(100));
+set character_set_client=cp850, collation_connection=latin2_croatian_ci;
+insert into t1 (b) values(@@character_set_server);
+insert into t1 (b) values(@@collation_server);
+insert into t1 (b) values(@@character_set_client);
+insert into t1 (b) values(@@character_set_connection);
+insert into t1 (b) values(@@collation_connection);
+
+--- --master--
+select * from t1 order by a;
+a	b
+1	armscii8
+2	armscii_bin
+3	cp850
+4	latin2
+5	latin2_croatian_ci
+
+--- --slave--
+select * from test2.t1 order by a;
+a	b
+1	armscii8
+2	armscii_bin
+3	cp850
+4	latin2
+5	latin2_croatian_ci
+set character_set_client=latin1, collation_connection=latin1_german1_ci;
+truncate table t1;
+insert into t1 (b) values(@@collation_connection);
+insert into t1 (b) values(LEAST("Müller","Muffler"));
+set collation_connection=latin1_german2_ci;
+insert into t1 (b) values(@@collation_connection);
+insert into t1 (b) values(LEAST("Müller","Muffler"));
+
+--- --master--
+select * from t1 order by a;
+a	b
+1	latin1_german1_ci
+2	Muffler
+3	latin1_german2_ci
+4	Müller
+
+--- --slave--
+select * from test2.t1 order by a;
+a	b
+1	latin1_german1_ci
+2	Muffler
+3	latin1_german2_ci
+4	Müller
+load data infile '../../std_data/words.dat' into table t1 (b);
+set @a= _cp850 'Müller' collate cp850_general_ci;
+truncate table t1;
+insert into t1 (b) values(collation(@a));
+
+--- --master--
+select * from t1 order by a;
+a	b
+1	cp850_general_ci
+
+--- --slave--
+select * from test2.t1 order by a;
+a	b
+1	cp850_general_ci
+drop database test2;
+drop database test3;
+show binlog events from 79;
+Log_name	Pos	Event_type	Server_id	Orig_log_pos	Info
+master-bin.000001	79	Query	1	79	use `test`; create database test2 character set latin2
+master-bin.000001	156	Query	1	156	use `test`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=8,COLLATION_DATABASE=8,COLLATION_SERVER=30
+master-bin.000001	290	Query	1	290	use `test`; create database test3
+master-bin.000001	346	Query	1	346	use `test`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=8,COLLATION_DATABASE=8,COLLATION_SERVER=64
+master-bin.000001	480	Query	1	480	use `test`; drop database test3
+master-bin.000001	534	Query	1	534	use `test`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=8,COLLATION_DATABASE=8,COLLATION_SERVER=64
+master-bin.000001	668	Query	1	668	use `test`; create database test3
+master-bin.000001	724	Query	1	724	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=8,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	859	Query	1	859	use `test2`; create table t1 (a int auto_increment primary key, b varchar(100))
+master-bin.000001	961	Query	1	961	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=4,COLLATION_CONNECTION=27,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	1097	Intvar	1	1097	INSERT_ID=1
+master-bin.000001	1125	Query	1	1125	use `test2`; insert into t1 (b) values(@@character_set_server)
+master-bin.000001	1210	Query	1	1210	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=4,COLLATION_CONNECTION=27,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	1346	Intvar	1	1346	INSERT_ID=2
+master-bin.000001	1374	Query	1	1374	use `test2`; insert into t1 (b) values(@@collation_server)
+master-bin.000001	1455	Query	1	1455	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=4,COLLATION_CONNECTION=27,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	1591	Intvar	1	1591	INSERT_ID=3
+master-bin.000001	1619	Query	1	1619	use `test2`; insert into t1 (b) values(@@character_set_client)
+master-bin.000001	1704	Query	1	1704	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=4,COLLATION_CONNECTION=27,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	1840	Intvar	1	1840	INSERT_ID=4
+master-bin.000001	1868	Query	1	1868	use `test2`; insert into t1 (b) values(@@character_set_connection)
+master-bin.000001	1957	Query	1	1957	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=4,COLLATION_CONNECTION=27,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	2093	Intvar	1	2093	INSERT_ID=5
+master-bin.000001	2121	Query	1	2121	use `test2`; insert into t1 (b) values(@@collation_connection)
+master-bin.000001	2206	Query	1	2206	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=5,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	2341	Query	1	2341	use `test2`; truncate table t1
+master-bin.000001	2394	Query	1	2394	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=5,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	2529	Intvar	1	2529	INSERT_ID=1
+master-bin.000001	2557	Query	1	2557	use `test2`; insert into t1 (b) values(@@collation_connection)
+master-bin.000001	2642	Query	1	2642	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=5,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	2777	Intvar	1	2777	INSERT_ID=2
+master-bin.000001	2805	Query	1	2805	use `test2`; insert into t1 (b) values(LEAST("Müller","Muffler"))
+master-bin.000001	2893	Query	1	2893	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	3029	Intvar	1	3029	INSERT_ID=3
+master-bin.000001	3057	Query	1	3057	use `test2`; insert into t1 (b) values(@@collation_connection)
+master-bin.000001	3142	Query	1	3142	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	3278	Intvar	1	3278	INSERT_ID=4
+master-bin.000001	3306	Query	1	3306	use `test2`; insert into t1 (b) values(LEAST("Müller","Muffler"))
+master-bin.000001	3394	Query	1	3394	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	3530	Intvar	1	3530	INSERT_ID=74
+master-bin.000001	3558	Create_file	1	3558	db=test2;table=t1;file_id=1;block_len=581
+master-bin.000001	4226	Query	1	4226	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	4362	Intvar	1	4362	INSERT_ID=5
+master-bin.000001	4390	Exec_load	1	4390	;file_id=1
+master-bin.000001	4413	Query	1	4413	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	4549	Query	1	4549	use `test2`; truncate table t1
+master-bin.000001	4602	Query	1	4602	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	4738	Intvar	1	4738	INSERT_ID=1
+master-bin.000001	4766	User var	1	4766	@`a`=_cp850'Müller' COLLATE cp850_general_ci
+master-bin.000001	4806	Query	1	4806	use `test2`; insert into t1 (b) values(collation(@a))
+master-bin.000001	4882	Query	1	4882	use `test2`; SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	5018	Query	1	5018	use `test2`; drop database test2
+master-bin.000001	5073	Query	1	5073	SET ONE_SHOT CHARACTER_SET_CLIENT=8,COLLATION_CONNECTION=31,COLLATION_DATABASE=9,COLLATION_SERVER=64
+master-bin.000001	5204	Query	1	5204	drop database test3
+set global character_set_server=latin2;
+ERROR HY000: Binary logging and replication forbid changing the global server character set or collation
+set global character_set_server=latin2;
+ERROR HY000: Binary logging and replication forbid changing the global server character set or collation
+set one_shot @@character_set_server=latin5;
+set @@max_join_size=1000;
+select @@character_set_server;
+@@character_set_server
+latin5
+select @@character_set_server;
+@@character_set_server
+latin1
+set @@character_set_server=latin5;
+select @@character_set_server;
+@@character_set_server
+latin5
+select @@character_set_server;
+@@character_set_server
+latin5
+set one_shot max_join_size=10;
+ERROR HY000: The SET ONE_SHOT syntax is reserved for purposes internal to the MySQL server
+set character_set_client=9999999;
+ERROR 42000: Unknown character set: '9999999'
+set collation_server=9999998;
+ERROR HY000: Unknown collation: '9999998'
+use test;
+CREATE TABLE t1 (c1 VARBINARY(255), c2 VARBINARY(255));
+SET CHARACTER_SET_CLIENT=koi8r,
+CHARACTER_SET_CONNECTION=cp1251, 
+CHARACTER_SET_RESULTS=koi8r;
+INSERT INTO t1 (c1, c2) VALUES ('îÕ, ÚÁ ÒÙÂÁÌËÕ','îÕ, ÚÁ ÒÙÂÁÌËÕ');
+select hex(c1), hex(c2) from t1;
+hex(c1)	hex(c2)
+CDF32C20E7E020F0FBE1E0EBEAF3	CDF32C20E7E020F0FBE1E0EBEAF3
+select hex(c1), hex(c2) from t1;
+hex(c1)	hex(c2)
+CDF32C20E7E020F0FBE1E0EBEAF3	CDF32C20E7E020F0FBE1E0EBEAF3
+drop table t1;
diff --git a/mysql-test/r/rpl_server_id1.result b/mysql-test/r/rpl_server_id1.result
index 8c383802de4..32e14b053d7 100644
--- a/mysql-test/r/rpl_server_id1.result
+++ b/mysql-test/r/rpl_server_id1.result
@@ -15,8 +15,5 @@ start slave;
 insert into t1 values (1);
 show status like "slave_running";
 Variable_name	Value
-Slave_running	ON
-select * from t1;
-n
-1
+Slave_running	OFF
 drop table t1;
diff --git a/mysql-test/r/rpl_user_variables.result b/mysql-test/r/rpl_user_variables.result
index 71147772ac4..7bb5dc163ea 100644
--- a/mysql-test/r/rpl_user_variables.result
+++ b/mysql-test/r/rpl_user_variables.result
@@ -86,11 +86,11 @@ slave-bin.000001	313	Query	1	313	use `test`; insert into t1 values (@i1), (@i2),
 slave-bin.000001	396	User var	2	396	@r1=12.5
 slave-bin.000001	439	User var	2	439	@r2=-12.5
 slave-bin.000001	482	Query	1	482	use `test`; insert into t1 values (@r1), (@r2)
-slave-bin.000001	551	User var	2	551	@s1='This is a test'
-slave-bin.000001	600	User var	2	600	@s2=''
-slave-bin.000001	635	User var	2	635	@s3='abc'def'
-slave-bin.000001	677	User var	2	677	@s4='abc\def'
-slave-bin.000001	719	User var	2	719	@s5='abc'def'
+slave-bin.000001	551	User var	2	551	@s1=_latin1'This is a test' COLLATE latin1_swedish_ci
+slave-bin.000001	600	User var	2	600	@s2=_latin1'' COLLATE latin1_swedish_ci
+slave-bin.000001	635	User var	2	635	@s3=_latin1'abc'def' COLLATE latin1_swedish_ci
+slave-bin.000001	677	User var	2	677	@s4=_latin1'abc\def' COLLATE latin1_swedish_ci
+slave-bin.000001	719	User var	2	719	@s5=_latin1'abc'def' COLLATE latin1_swedish_ci
 slave-bin.000001	761	Query	1	761	use `test`; insert into t1 values (@s1), (@s2), (@s3), (@s4), (@s5)
 slave-bin.000001	851	User var	2	851	@n1=NULL
 slave-bin.000001	877	Query	1	877	use `test`; insert into t1 values (@n1)
@@ -99,7 +99,7 @@ slave-bin.000001	965	Query	1	965	use `test`; insert into t1 values (@n2)
 slave-bin.000001	1027	Query	1	1027	use `test`; insert into t1 values (@a:=0), (@a:=@a+1), (@a:=@a+1)
 slave-bin.000001	1115	User var	2	1115	@a=2
 slave-bin.000001	1157	Query	1	1157	use `test`; insert into t1 values (@a+(@b:=@a+1))
-slave-bin.000001	1229	User var	2	1229	@q='abc'
+slave-bin.000001	1229	User var	2	1229	@q=_latin1'abc' COLLATE latin1_swedish_ci
 slave-bin.000001	1266	Query	1	1266	use `test`; insert t1 values (@q), (@q:=concat(@q, 'n1')), (@q:=concat(@q, 'n2'))
 slave-bin.000001	1370	User var	2	1370	@a=5
 slave-bin.000001	1412	Query	1	1412	use `test`; insert into t1 values (@a),(@a)
diff --git a/mysql-test/r/user_var.result b/mysql-test/r/user_var.result
index a9351d2f1fb..605780a7280 100644
--- a/mysql-test/r/user_var.result
+++ b/mysql-test/r/user_var.result
@@ -162,3 +162,36 @@ charset(@a)	collation(@a)	coercibility(@a)
 latin2	latin2_bin	0
 select (@a:=_latin2'test' collate latin2_bin) = _latin2'TEST' collate latin2_general_ci;
 ERROR HY000: Illegal mix of collations (latin2_bin,EXPLICIT) and (latin2_general_ci,EXPLICIT) for operation '='
+create table t1 (a varchar(50));
+reset master;
+SET TIMESTAMP=10000;
+SET @`a b`='hello';
+INSERT INTO t1 VALUES(@`a b`);
+set @var1= "';aaa";
+insert into t1 values (@var1);
+create table t2 (c char(30)) charset=ucs2;
+set @v=convert('abc' using ucs2);
+insert into t2 values (@v);
+show binlog events from 79;
+Log_name	Pos	Event_type	Server_id	Orig_log_pos	Info
+master-bin.000001	79	User var	1	79	@`a b`=_latin1'hello' COLLATE latin1_swedish_ci
+master-bin.000001	120	Query	1	120	use `test`; INSERT INTO t1 VALUES(@`a b`)
+master-bin.000001	184	User var	1	184	@`var1`=_latin1'\';aaa' COLLATE latin1_swedish_ci
+master-bin.000001	226	Query	1	226	use `test`; insert into t1 values (@var1)
+master-bin.000001	290	Query	1	290	use `test`; create table t2 (c char(30)) charset=ucs2
+master-bin.000001	366	User var	1	366	@`v`=_ucs2'\0a\0b\0c' COLLATE ucs2_general_ci
+master-bin.000001	406	Query	1	406	use `test`; insert into t2 values (@v)
+/*!40019 SET @@session.max_insert_delayed_threads=0*/;
+SET @`a b`:=_latin1'hello' COLLATE latin1_swedish_ci;
+use test;
+SET TIMESTAMP=10000;
+INSERT INTO t1 VALUES(@`a b`);
+SET @`var1`:=_latin1'\';aaa' COLLATE latin1_swedish_ci;
+SET TIMESTAMP=10000;
+insert into t1 values (@var1);
+SET TIMESTAMP=10000;
+create table t2 (c char(30)) charset=ucs2;
+SET @`v`:=_ucs2'\0a\0b\0c' COLLATE ucs2_general_ci;
+SET TIMESTAMP=10000;
+insert into t2 values (@v);
+drop table t1, t2;
diff --git a/mysql-test/t/rpl_charset.test b/mysql-test/t/rpl_charset.test
new file mode 100644
index 00000000000..c13b57a3108
--- /dev/null
+++ b/mysql-test/t/rpl_charset.test
@@ -0,0 +1,153 @@
+# Replication of character sets.
+# This test will fail if the server/client does not support enough charsets.
+
+# Remember that there currently exists
+# Bug #2326: Charset of table is determined by charset of db only if "USE db;"
+
+source include/master-slave.inc;
+--disable_warnings
+drop database if exists test2;
+drop database if exists test3;
+--enable_warnings
+
+create database test2 character set latin2;
+set @@character_set_server=latin5;      
+create database test3;
+--disable_query_log
+select "--- --master--" as "";
+--enable_query_log
+show create database test2;
+show create database test3;
+sync_slave_with_master;
+--disable_query_log
+select "--- --slave--" as "";
+--enable_query_log
+show create database test2;
+show create database test3;
+
+connection master;
+set @@collation_server=armscii_bin;
+drop database test3;
+create database test3;
+--disable_query_log
+select "--- --master--" as "";
+--enable_query_log
+show create database test3;
+sync_slave_with_master;
+--disable_query_log
+select "--- --slave--" as "";
+--enable_query_log
+show create database test3;
+
+connection master;
+use test2;
+create table t1 (a int auto_increment primary key, b varchar(100));
+set character_set_client=cp850, collation_connection=latin2_croatian_ci;
+insert into t1 (b) values(@@character_set_server);
+insert into t1 (b) values(@@collation_server);
+# character_set_database and collation_database are not tested as they
+# are not replicated (Bar said that this variable may be removed shortly).
+insert into t1 (b) values(@@character_set_client);
+# collation_client does not exist
+insert into t1 (b) values(@@character_set_connection);
+insert into t1 (b) values(@@collation_connection);
+--disable_query_log
+select "--- --master--" as "";
+--enable_query_log
+select * from t1 order by a;
+sync_slave_with_master;
+--disable_query_log
+select "--- --slave--" as "";
+--enable_query_log
+select * from test2.t1 order by a;
+
+connection master;
+set character_set_client=latin1, collation_connection=latin1_german1_ci;
+truncate table t1;
+insert into t1 (b) values(@@collation_connection);
+insert into t1 (b) values(LEAST("Müller","Muffler"));
+set collation_connection=latin1_german2_ci;
+insert into t1 (b) values(@@collation_connection);
+insert into t1 (b) values(LEAST("Müller","Muffler"));
+--disable_query_log
+select "--- --master--" as "";
+--enable_query_log
+select * from t1 order by a;
+sync_slave_with_master;
+--disable_query_log
+select "--- --slave--" as "";
+--enable_query_log
+select * from test2.t1 order by a;
+
+# See if SET ONE_SHOT gets into binlog when LOAD DATA
+connection master;
+load data infile '../../std_data/words.dat' into table t1 (b);
+
+# See if user var is prefixed with collation in binlog and replicated well.
+# Note: replication of user variables is broken as far as derivation is
+# concerned. That's because when we store a user variable in the binlog,
+# we lose its derivation. So later on the slave, it's impossible to
+# know if the collation was explicit or not, so we use DERIVATION_NONE,
+# which provokes error messages (like 'Illegal mix of collation') when
+# we replay the master's INSERT/etc statements.
+set @a= _cp850 'Müller' collate cp850_general_ci;
+truncate table t1;
+insert into t1 (b) values(collation(@a));
+--disable_query_log
+select "--- --master--" as "";
+--enable_query_log
+select * from t1 order by a;
+sync_slave_with_master;
+--disable_query_log
+select "--- --slave--" as "";
+--enable_query_log
+select * from test2.t1 order by a;
+
+connection master;
+drop database test2;
+drop database test3;
+show binlog events from 79;
+sync_slave_with_master;
+
+# Check that we can't change global.collation_server
+
+error 1105;
+set global character_set_server=latin2;
+connection master;
+error 1105;
+set global character_set_server=latin2;
+
+# Check that SET ONE_SHOT is really one shot
+
+set one_shot @@character_set_server=latin5;
+set @@max_join_size=1000;
+select @@character_set_server;
+select @@character_set_server;
+set @@character_set_server=latin5;
+select @@character_set_server;
+select @@character_set_server;
+
+# ONE_SHOT on not charset/collation stuff is not allowed
+error 1105;
+set one_shot max_join_size=10;
+
+# Test of wrong character set numbers;
+error 1115;
+set character_set_client=9999999;
+error 1273;
+set collation_server=9999998;
+
+# This one was contributed by Sergey Petrunia (BUG#3943)
+
+use test;
+CREATE TABLE t1 (c1 VARBINARY(255), c2 VARBINARY(255));
+SET CHARACTER_SET_CLIENT=koi8r,
+ CHARACTER_SET_CONNECTION=cp1251, 
+ CHARACTER_SET_RESULTS=koi8r;
+INSERT INTO t1 (c1, c2) VALUES ('îÕ, ÚÁ ÒÙÂÁÌËÕ','îÕ, ÚÁ ÒÙÂÁÌËÕ');
+select hex(c1), hex(c2) from t1;
+sync_slave_with_master;
+select hex(c1), hex(c2) from t1;
+connection master;
+drop table t1;
+sync_slave_with_master;
diff --git a/mysql-test/t/rpl_server_id1.test b/mysql-test/t/rpl_server_id1.test
index aefcb81c930..4d504325294 100644
--- a/mysql-test/t/rpl_server_id1.test
+++ b/mysql-test/t/rpl_server_id1.test
@@ -1,5 +1,8 @@
-# This test checks that a slave does not execute queries originating
-# from itself, by default.
+# This test checks that the slave I/O thread refuses to start if slave
+# and master have the same server id (because this is a useless setup,
+# and otherwise SHOW SLAVE STATUS shows progress but all queries are
+# ignored, which has caught our customers), unless
+# --replicate-same-server-id.
 
 source include/master-slave.inc;
 connection slave;
@@ -18,5 +21,4 @@ insert into t1 values (1);
 # (when slave is its own master without --replicate-same-server-id)
 sleep 2; # enough time for the event to be replicated (it should not)
 show status like "slave_running";
-select * from t1;
 drop table t1;
diff --git a/mysql-test/t/user_var.test b/mysql-test/t/user_var.test
index a28b327cf58..601724e68c8 100644
--- a/mysql-test/t/user_var.test
+++ b/mysql-test/t/user_var.test
@@ -99,3 +99,24 @@ select (@a:=_latin2'test' collate latin2_bin) = _latin2'TEST';
 select charset(@a),collation(@a),coercibility(@a);
 --error 1267
 select (@a:=_latin2'test' collate latin2_bin) = _latin2'TEST' collate latin2_general_ci;
+
+# Check that user variables are binlogged correctly (BUG#3875)
+create table t1 (a varchar(50));
+reset master;
+SET TIMESTAMP=10000;
+SET @`a b`='hello';
+INSERT INTO t1 VALUES(@`a b`);
+set @var1= "';aaa";
+insert into t1 values (@var1);
+create table t2 (c char(30)) charset=ucs2;
+set @v=convert('abc' using ucs2);
+insert into t2 values (@v);
+show binlog events from 79;
+# more important than SHOW BINLOG EVENTS, mysqlbinlog (where we
+# absolutely need variables names to be quoted and strings to be
+# escaped).
+--replace_result $MYSQL_TEST_DIR MYSQL_TEST_DIR
+--exec $MYSQL_BINLOG --short-form $MYSQL_TEST_DIR/var/log/master-bin.000001 
+drop table t1, t2;
+
+
diff --git a/sql/lex.h b/sql/lex.h
index e5bc537c213..f8ead8a8d2d 100644
--- a/sql/lex.h
+++ b/sql/lex.h
@@ -310,6 +310,7 @@ static SYMBOL symbols[] = {
   { "OFFSET",		SYM(OFFSET_SYM)},
   { "OLD_PASSWORD",	SYM(OLD_PASSWORD)},
   { "ON",		SYM(ON)},
+  { "ONE_SHOT",		SYM(ONE_SHOT_SYM)},
   { "OPEN",		SYM(OPEN_SYM)},
   { "OPTIMIZE",		SYM(OPTIMIZE)},
   { "OPTION",		SYM(OPTION)},
diff --git a/sql/log.cc b/sql/log.cc
index 8df5ea5096b..e7a142230b1 100644
--- a/sql/log.cc
+++ b/sql/log.cc
@@ -1231,6 +1231,40 @@ bool MYSQL_LOG::write(Log_event* event_info)
 
     if (thd)
     {
+#if MYSQL_VERSION_ID < 50000
+      /*
+        To make replication of charsets working in 4.1 we are writing values
+        of charset related variables before every statement in the binlog,
+        if values of those variables differ from global server-wide defaults.
+        We are using SET ONE_SHOT command so that the charset vars get reset
+        to default after the first non-SET statement.
+        In the next 5.0 this won't be needed as we will use the new binlog
+        format to store charset info.
+      */
+      if ((thd->variables.character_set_client->number !=
+           global_system_variables.collation_server->number) ||
+          (thd->variables.character_set_client->number !=
+           thd->variables.collation_connection->number) ||
+          (thd->variables.collation_server->number !=
+           thd->variables.collation_connection->number))
+      {
+	char buf[200];
+        int written= my_snprintf(buf, sizeof(buf)-1,
+                    "SET ONE_SHOT CHARACTER_SET_CLIENT=%lu,\
+COLLATION_CONNECTION=%lu,COLLATION_DATABASE=%lu,COLLATION_SERVER=%lu",
+                             thd->variables.character_set_client->number,
+                             thd->variables.collation_connection->number,
+                             thd->variables.collation_database->number,
+                             thd->variables.collation_server->number);
+	Query_log_event e(thd, buf, written, 0);
+	e.set_log_pos(this);
+	if (e.write(file))
+	  goto err;
+      }
+#endif
+
+      /* Add logging of timezones here */
+
       if (thd->last_insert_id_used)
       {
 	Intvar_log_event e(thd,(uchar) LAST_INSERT_ID_EVENT,
diff --git a/sql/log_event.cc b/sql/log_event.cc
index fd65ec64a76..a76725a95e0 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -2176,7 +2176,7 @@ int Rand_log_event::exec_event(struct st_relay_log_info* rli)
 void User_var_log_event::pack_info(Protocol* protocol)
 {
   char *buf= 0;
-  uint val_offset= 2 + name_len;
+  uint val_offset= 4 + name_len;
   uint event_len= val_offset;
 
   if (is_null)
@@ -2200,16 +2200,21 @@ void User_var_log_event::pack_info(Protocol* protocol)
       event_len= longlong10_to_str(uint8korr(val), buf + val_offset,-10)-buf;
       break;
     case STRING_RESULT:
-      /*
-	This is correct as pack_info is used for SHOW BINLOG command
-	only. But be carefull this is may be incorrect in other cases as
-	string may contain \ and '.
-      */
-      event_len= val_offset + 2 + val_len;
-      buf= my_malloc(event_len, MYF(MY_WME));
-      buf[val_offset]= '\'';
-      memcpy(buf + val_offset + 1, val, val_len);
-      buf[val_offset + val_len + 1]= '\'';
+      /* 15 is for 'COLLATE' and other chars */
+      buf= my_malloc(event_len+val_len*2+1+2*MY_CS_NAME_SIZE+15, MYF(MY_WME));
+      CHARSET_INFO *cs;
+      if (!(cs= get_charset(charset_number, MYF(0))))
+      {
+        strmov(buf+val_offset, "???");
+        event_len+= 3;
+      }
+      else
+      {
+        char *p= strxmov(buf + val_offset, "_", cs->csname, "'", NullS);
+        p+= escape_string_for_mysql(&my_charset_bin, p, val, val_len);
+        p= strxmov(p, "' COLLATE ", cs->name, NullS);
+        event_len= p-buf;
+      }
       break;
     case ROW_RESULT:
     default:
@@ -2218,8 +2223,10 @@ void User_var_log_event::pack_info(Protocol* protocol)
     }
   }
   buf[0]= '@';
-  buf[1+name_len]= '=';
-  memcpy(buf+1, name, name_len);
+  buf[1]= '`';
+  buf[2+name_len]= '`';
+  buf[3+name_len]= '=';
+  memcpy(buf+2, name, name_len);
   protocol->store(buf, event_len, &my_charset_bin);
   my_free(buf, MYF(MY_ALLOW_ZERO_PTR));
 }
@@ -2311,8 +2318,9 @@ void User_var_log_event::print(FILE* file, bool short_form, char* last_db)
     fprintf(file, "\tUser_var\n");
   }
 
-  fprintf(file, "SET @");
+  fprintf(file, "SET @`");
   my_fwrite(file, (byte*) name, (uint) (name_len), MYF(MY_NABP | MY_WME));
+  fprintf(file, "`");
 
   if (is_null)
   {
@@ -2332,7 +2340,36 @@ void User_var_log_event::print(FILE* file, bool short_form, char* last_db)
       fprintf(file, ":=%s;\n", int_buf);
       break;
     case STRING_RESULT:
-      fprintf(file, ":='%s';\n", val);
+    {
+      char *p;
+      if (!(p= (char *)my_alloca(2*val_len+1)))
+        break; // no error, as we are 'void'
+      escape_string_for_mysql(&my_charset_bin, p, val, val_len);
+#if MYSQL_VERSION_ID < 50000
+      /*
+        For proper behaviour when mysqlbinlog|mysql, we need to explicitely
+        specify the variable's collation. It will however cause problems when
+        people want to mysqlbinlog|mysql into another server not supporting the
+        character set. But there's not much to do about this and it's unlikely.
+      */
+      CHARSET_INFO *cs;
+      if (!(cs= get_charset(charset_number, MYF(0))))
+        /*
+          Generate an unusable command (=> syntax error) is probably the best
+          thing we can do here.
+        */
+        fprintf(file, ":=???;\n");
+      else
+        fprintf(file, ":=_%s'%s' COLLATE %s;\n", cs->csname, p, cs->name);
+#else
+      /*
+        In 5.0 we will have some SET CHARACTER_SET_ect automatically printed
+        for all events where it's needed.
+      */
+      fprintf(file, ":='%s';\n", p);
+#endif
+      my_afree(p);
+    }
       break;
     case ROW_RESULT:
     default:
@@ -2353,7 +2390,9 @@ void User_var_log_event::print(FILE* file, bool short_form, char* last_db)
 int User_var_log_event::exec_event(struct st_relay_log_info* rli)
 {
   Item *it= 0;
-  CHARSET_INFO *charset= get_charset(charset_number, MYF(0));
+  CHARSET_INFO *charset;
+  if (!(charset= get_charset(charset_number, MYF(MY_WME))))
+    return 1;
   LEX_STRING user_var_name;
   user_var_name.str= name;
   user_var_name.length= name_len;
diff --git a/sql/set_var.cc b/sql/set_var.cc
index b3b0153652b..7fdc10858dd 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -1708,19 +1708,31 @@ CHARSET_INFO *get_old_charset_by_name(const char *name)
 bool sys_var_collation::check(THD *thd, set_var *var)
 {
   CHARSET_INFO *tmp;
-  char buff[80];
-  String str(buff,sizeof(buff), system_charset_info), *res;
 
-  if (!(res=var->value->val_str(&str)))
+  if (var->value->result_type() == STRING_RESULT)
   {
-    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
-    return 1;
+    char buff[80];
+    String str(buff,sizeof(buff), system_charset_info), *res;
+    if (!(res=var->value->val_str(&str)))
+    {
+      my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
+      return 1;
+    }
+    if (!(tmp=get_charset_by_name(res->c_ptr(),MYF(0))))
+    {
+      my_error(ER_UNKNOWN_COLLATION, MYF(0), res->c_ptr());
+      return 1;
+    }
   }
-
-  if (!(tmp=get_charset_by_name(res->c_ptr(),MYF(0))))
+  else // INT_RESULT
   {
-    my_error(ER_UNKNOWN_COLLATION, MYF(0), res->c_ptr());
-    return 1;
+    if (!(tmp=get_charset(var->value->val_int(),MYF(0))))
+    {
+      char buf[20];
+      int10_to_str(var->value->val_int(), buf, -10);
+      my_error(ER_UNKNOWN_COLLATION, MYF(0), buf);
+      return 1;
+    }
   }
   var->save_result.charset= tmp;	// Save for update
   return 0;
@@ -1730,23 +1742,36 @@ bool sys_var_collation::check(THD *thd, set_var *var)
 bool sys_var_character_set::check(THD *thd, set_var *var)
 {
   CHARSET_INFO *tmp;
-  char buff[80];
-  String str(buff,sizeof(buff), system_charset_info), *res;
 
-  if (!(res=var->value->val_str(&str)))
-  { 
-    if (!nullable)
+  if (var->value->result_type() == STRING_RESULT)
+  {
+    char buff[80];
+    String str(buff,sizeof(buff), system_charset_info), *res;
+    if (!(res=var->value->val_str(&str)))
     {
-      my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
+      if (!nullable)
+      {
+        my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
+        return 1;
+      }
+      tmp= NULL;
+    }
+    else if (!(tmp=get_charset_by_csname(res->c_ptr(),MY_CS_PRIMARY,MYF(0))) &&
+             !(tmp=get_old_charset_by_name(res->c_ptr())))
+    {
+      my_error(ER_UNKNOWN_CHARACTER_SET, MYF(0), res->c_ptr());
       return 1;
     }
-    tmp= NULL;
   }
-  else if (!(tmp=get_charset_by_csname(res->c_ptr(),MY_CS_PRIMARY,MYF(0))) &&
-	   !(tmp=get_old_charset_by_name(res->c_ptr())))
+  else // INT_RESULT
   {
-    my_error(ER_UNKNOWN_CHARACTER_SET, MYF(0), res->c_ptr());
-    return 1;
+    if (!(tmp=get_charset(var->value->val_int(),MYF(0))))
+    {
+      char buf[20];
+      int10_to_str(var->value->val_int(), buf, -10);
+      my_error(ER_UNKNOWN_CHARACTER_SET, MYF(0), buf);
+      return 1;
+    }
   }
   var->save_result.charset= tmp;	// Save for update
   return 0;
@@ -1859,6 +1884,20 @@ void sys_var_character_set_server::set_default(THD *thd, enum_var_type type)
  }
 }
 
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+bool sys_var_character_set_server::check(THD *thd, set_var *var)
+{
+  if ((var->type == OPT_GLOBAL) &&
+      (mysql_bin_log.is_open() ||
+       active_mi->slave_running || active_mi->rli.slave_running))
+  {
+    my_printf_error(0, "Binary logging and replication forbid changing \
+the global server character set or collation", MYF(0));
+    return 1;
+  }
+  return sys_var_character_set::check(thd,var);
+}
+#endif
 
 CHARSET_INFO ** sys_var_character_set_database::ci_ptr(THD *thd,
 						       enum_var_type type)
@@ -1952,6 +1991,20 @@ void sys_var_collation_database::set_default(THD *thd, enum_var_type type)
  }
 }
 
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+bool sys_var_collation_server::check(THD *thd, set_var *var)
+{
+  if ((var->type == OPT_GLOBAL) &&
+      (mysql_bin_log.is_open() ||
+       active_mi->slave_running || active_mi->rli.slave_running))
+  {
+    my_printf_error(0, "Binary logging and replication forbid changing \
+the global server character set or collation", MYF(0));
+    return 1;
+  }
+  return sys_var_collation::check(thd,var);
+}
+#endif
 
 bool sys_var_collation_server::update(THD *thd, set_var *var)
 {
@@ -2524,6 +2577,36 @@ int sql_set_variables(THD *thd, List<set_var_base> *var_list)
 }
 
 
+/*
+  Say if all variables set by a SET support the ONE_SHOT keyword (currently,
+  only character set and collation do; later timezones will).
+
+  SYNOPSIS
+
+  not_all_support_one_shot
+    set_var	List of variables to update
+
+  NOTES
+    It has a "not_" because it makes faster tests (no need to "!")
+
+    RETURN VALUE
+    0	all variables of the list support ONE_SHOT
+    1	at least one does not support ONE_SHOT
+*/
+
+bool not_all_support_one_shot(List<set_var_base> *var_list)
+{
+  List_iterator_fast<set_var_base> it(*var_list);
+  set_var_base *var;
+  while ((var= it++))
+  {
+    if (var->no_support_one_shot())
+      return 1;
+  }
+  return 0;
+}
+
+
 /*****************************************************************************
   Functions to handle SET mysql_internal_variable=const_expr
 *****************************************************************************/
diff --git a/sql/set_var.h b/sql/set_var.h
index 699f320bbd9..64bdfdb718b 100644
--- a/sql/set_var.h
+++ b/sql/set_var.h
@@ -49,10 +49,20 @@ public:
   const char *name;
   
   sys_after_update_func after_update;
-  sys_var(const char *name_arg) :name(name_arg),after_update(0)
-  {}
+#if MYSQL_VERSION_ID < 50000
+  bool no_support_one_shot;
+#endif
+  sys_var(const char *name_arg)
+    :name(name_arg), after_update(0)
+#if MYSQL_VERSION_ID < 50000
+    , no_support_one_shot(1)
+#endif
+    {}
   sys_var(const char *name_arg,sys_after_update_func func)
-    :name(name_arg),after_update(func)
+    :name(name_arg), after_update(func)
+#if MYSQL_VERSION_ID < 50000
+    , no_support_one_shot(1)
+#endif
   {}
   virtual ~sys_var() {}
   virtual bool check(THD *thd, set_var *var);
@@ -487,12 +497,17 @@ public:
 class sys_var_collation :public sys_var_thd
 {
 public:
-  sys_var_collation(const char *name_arg) :sys_var_thd(name_arg) {}
+  sys_var_collation(const char *name_arg) :sys_var_thd(name_arg)
+    {
+#if MYSQL_VERSION_ID < 50000
+    no_support_one_shot= 0;
+#endif
+    }
   bool check(THD *thd, set_var *var);
 SHOW_TYPE type() { return SHOW_CHAR; }
   bool check_update_type(Item_result type)
   {
-    return type != STRING_RESULT;		/* Only accept strings */
+    return ((type != STRING_RESULT) && (type != INT_RESULT));
   }
   bool check_default(enum_var_type type) { return 0; }
   virtual void set_default(THD *thd, enum_var_type type)= 0;
@@ -502,13 +517,23 @@ class sys_var_character_set :public sys_var_thd
 {
 public:
   bool nullable;
-  sys_var_character_set(const char *name_arg) :sys_var_thd(name_arg) 
-  { nullable= 0; }
+  sys_var_character_set(const char *name_arg) :
+    sys_var_thd(name_arg)
+  {
+    nullable= 0;
+#if MYSQL_VERSION_ID < 50000
+    /*
+      In fact only almost all variables derived from sys_var_character_set
+      support ONE_SHOT; character_set_results doesn't. But that's good enough.
+    */
+    no_support_one_shot= 0;
+#endif
+  }
   bool check(THD *thd, set_var *var);
   SHOW_TYPE type() { return SHOW_CHAR; }
   bool check_update_type(Item_result type)
   {
-    return type != STRING_RESULT;		/* Only accept strings */
+    return ((type != STRING_RESULT) && (type != INT_RESULT));
   }
   bool check_default(enum_var_type type) { return 0; }
   bool update(THD *thd, set_var *var);
@@ -541,6 +566,9 @@ class sys_var_character_set_server :public sys_var_character_set
 public:
   sys_var_character_set_server(const char *name_arg) :
     sys_var_character_set(name_arg) {}
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+  bool check(THD *thd, set_var *var);
+#endif
   void set_default(THD *thd, enum_var_type type);
   CHARSET_INFO **ci_ptr(THD *thd, enum_var_type type);
 };
@@ -576,6 +604,9 @@ class sys_var_collation_server :public sys_var_collation
 {
 public:
   sys_var_collation_server(const char *name_arg) :sys_var_collation(name_arg) {}
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+  bool check(THD *thd, set_var *var);
+#endif
   bool update(THD *thd, set_var *var);
   void set_default(THD *thd, enum_var_type type);
   byte *value_ptr(THD *thd, enum_var_type type, LEX_STRING *base);
@@ -689,7 +720,10 @@ public:
   virtual int check(THD *thd)=0;	/* To check privileges etc. */
   virtual int update(THD *thd)=0;	/* To set the value */
   /* light check for PS */
-  virtual   int light_check(THD *thd) { return check(thd); }
+  virtual int light_check(THD *thd) { return check(thd); }
+#if MYSQL_VERSION_ID < 50000
+  virtual bool no_support_one_shot() { return 1; }
+#endif
 };
 
 
@@ -731,6 +765,9 @@ public:
   int check(THD *thd);
   int update(THD *thd);
   int light_check(THD *thd);
+#if MYSQL_VERSION_ID < 50000
+  bool no_support_one_shot() { return var->no_support_one_shot; }
+#endif
 };
 
 
@@ -833,6 +870,7 @@ void set_var_init();
 void set_var_free();
 sys_var *find_sys_var(const char *str, uint length=0);
 int sql_set_variables(THD *thd, List<set_var_base> *var_list);
+bool not_all_support_one_shot(List<set_var_base> *var_list);
 void fix_delay_key_write(THD *thd, enum_var_type type);
 ulong fix_sql_mode(ulong sql_mode);
 extern sys_var_str sys_charset_system;
diff --git a/sql/slave.cc b/sql/slave.cc
index fa17a192b12..f88d828df1d 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -72,7 +72,7 @@ static int safe_sleep(THD* thd, int sec, CHECK_KILLED_FUNC thread_killed,
 static int request_table_dump(MYSQL* mysql, const char* db, const char* table);
 static int create_table_from_dump(THD* thd, MYSQL *mysql, const char* db,
 				  const char* table_name, bool overwrite);
-static int check_master_version_and_clock(MYSQL* mysql, MASTER_INFO* mi);
+static int get_master_version_and_clock(MYSQL* mysql, MASTER_INFO* mi);
 
 
 /*
@@ -1187,38 +1187,75 @@ slaves can't replicate a 5.0 or newer master.";
     break;
   }
 
-  MYSQL_RES *master_clock_res;
-  MYSQL_ROW master_clock_row;
-  time_t slave_clock;
-
-  if (mysql_real_query(mysql, "SELECT UNIX_TIMESTAMP()", 23))
-    errmsg= "\"SELECT UNIX_TIMESTAMP()\" failed on master"; 
-  else if (!(master_clock_res= mysql_store_result(mysql)))
+  /*
+    Compare the master and slave's clock. Do not die if master's clock is
+    unavailable (very old master not supporting UNIX_TIMESTAMP()?).
+  */
+  MYSQL_RES *master_res= 0;
+  MYSQL_ROW master_row;
+  
+  if (!mysql_real_query(mysql, "SELECT UNIX_TIMESTAMP()", 23) &&
+      (master_res= mysql_store_result(mysql)) &&
+      (master_row= mysql_fetch_row(master_res)))
   {
-    errmsg= "Could not read the result of \"SELECT UNIX_TIMESTAMP()\" on \
-master"; 
+    mi->clock_diff_with_master= 
+      (long) (time((time_t*) 0) - strtoul(master_row[0], 0, 10));
   }
-  else 
+  else
   {
-    if (!(master_clock_row= mysql_fetch_row(master_clock_res)))
-      errmsg= "Could not read a row from the result of \"SELECT \
-UNIX_TIMESTAMP()\" on master"; 
-    else
-    {
-      slave_clock= time((time_t*) 0);
-      mi->clock_diff_with_master= (long) (slave_clock -
-                                          strtoul(master_clock_row[0], 0, 10));
-      DBUG_PRINT("info",("slave_clock=%lu, master_clock=%s",
-                         slave_clock, master_clock_row[0]));
-    }
-  mysql_free_result(master_clock_res);
+    mi->clock_diff_with_master= 0; /* The "most sensible" value */
+    sql_print_error("Warning: \"SELECT UNIX_TIMESTAMP()\" failed on master, \
+do not trust column Seconds_Behind_Master of SHOW SLAVE STATUS");
+  }
+  if (master_res)
+    mysql_free_result(master_res);      
+ 
+  /*
+    Check that the master's server id and ours are different. Because if they
+    are equal (which can result from a simple copy of master's datadir to slave,
+    thus copying some my.cnf), replication will work but all events will be
+    skipped.
+    Do not die if SHOW VARIABLES LIKE 'SERVER_ID' fails on master (very old
+    master?).
+    Note: we could have put a @@SERVER_ID in the previous SELECT
+    UNIX_TIMESTAMP() instead, but this would not have worked on 3.23 masters.
+  */
+  if (!mysql_real_query(mysql, "SHOW VARIABLES LIKE 'SERVER_ID'", 31) &&
+      (master_res= mysql_store_result(mysql)))
+  {
+    if ((master_row= mysql_fetch_row(master_res)) &&
+        (::server_id == strtoul(master_row[1], 0, 10)) &&
+        !replicate_same_server_id)
+      errmsg= "The slave I/O thread stops because master and slave have equal \
+MySQL server ids; these ids must be different for replication to work (or \
+the --replicate-same-server-id option must be used on slave but this does \
+not always make sense; please check the manual before using it).";
+    mysql_free_result(master_res);
+  }
+
+  /*
+    Check that the master's global character_set_server and ours are the same.
+    Not fatal if query fails (old master?).
+  */
+  if (!mysql_real_query(mysql, "SELECT @@GLOBAL.COLLATION_SERVER", 32) &&
+      (master_res= mysql_store_result(mysql)))
+  {
+    if ((master_row= mysql_fetch_row(master_res)) &&
+        strcmp(master_row[0], global_system_variables.collation_server->name))
+      errmsg= "The slave I/O thread stops because master and slave have \
+different values for the COLLATION_SERVER global variable. The values must \
+be equal for replication to work";
+    mysql_free_result(master_res);
   }
 
+  /* Add a timezones check here */
+
   if (errmsg)
   {
     sql_print_error(errmsg);
     return 1;
   }
+
   return 0;
 }
 
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 9d368db0229..f2978edc033 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -181,6 +181,7 @@ THD::THD():user_time(0), current_statement(0), is_fatal_error(0),
   current_linfo =  0;
   slave_thread = 0;
   variables.pseudo_thread_id= 0;
+  one_shot_set= 0;
   file_id = 0;
   warn_id= 0;
   db_charset= global_system_variables.collation_database;
diff --git a/sql/sql_class.h b/sql/sql_class.h
index d787dcabd00..676ee1b529f 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -801,7 +801,7 @@ public:
   /* scramble - random string sent to client on handshake */
   char	     scramble[SCRAMBLE_LENGTH+1];
 
-  bool       slave_thread;
+  bool       slave_thread, one_shot_set;
   bool	     locked, some_tables_deleted;
   bool       last_cuted_field;
   bool	     no_errors, password, is_fatal_error;
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index 92ed53cf814..3884c8f2674 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -611,7 +611,7 @@ typedef struct st_lex
   uint fk_delete_opt, fk_update_opt, fk_match_option;
   uint slave_thd_opt;
   uint8 describe;
-  bool drop_if_exists, drop_temporary, local_file;
+  bool drop_if_exists, drop_temporary, local_file, one_shot_set;
   bool in_comment, ignore_space, verbose, no_write_to_binlog;
   bool derived_tables;
   bool safe_to_cache_query;
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 7596e37de93..b6e9bd3dd80 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -2918,14 +2918,31 @@ unsent_create_error:
   }
 
   case SQLCOM_SET_OPTION:
+  {
+    List<set_var_base> *lex_var_list= &lex->var_list;
     if (tables && ((res= check_table_access(thd, SELECT_ACL, tables,0)) ||
 		   (res= open_and_lock_tables(thd,tables))))
       break;
-    if (!(res= sql_set_variables(thd, &lex->var_list)))
+    if (lex->one_shot_set && not_all_support_one_shot(lex_var_list))
+    {
+      my_printf_error(0, "The SET ONE_SHOT syntax is reserved for \
+purposes internal to the MySQL server", MYF(0));
+      res= -1;
+      break;
+    }
+    if (!(res= sql_set_variables(thd, lex_var_list)))
+    {
+      /*
+        If the previous command was a SET ONE_SHOT, we don't want to forget
+        about the ONE_SHOT property of that SET. So we use a |= instead of = .
+      */
+      thd->one_shot_set|= lex->one_shot_set;
       send_ok(thd);
+    }
     if (thd->net.report_error)
       res= -1;
     break;
+  }
 
   case SQLCOM_UNLOCK_TABLES:
     unlock_locked_tables(thd);
@@ -3377,6 +3394,29 @@ unsent_create_error:
     break;
   }
   thd->proc_info="query end";			// QQ
+  if (thd->one_shot_set)
+    {
+      /*
+        If this is a SET, do nothing. This is to allow mysqlbinlog to print
+        many SET commands (in this case we want the charset temp setting to
+        live until the real query). This is also needed so that SET
+        CHARACTER_SET_CLIENT... does not cancel itself immediately.
+      */
+      if (lex->sql_command != SQLCOM_SET_OPTION)
+      {
+        thd->variables.character_set_client=
+          global_system_variables.character_set_client;
+        thd->variables.collation_connection=
+          global_system_variables.collation_connection;
+        thd->variables.collation_database=
+          global_system_variables.collation_database;
+        thd->variables.collation_server=
+          global_system_variables.collation_server;
+        thd->update_charset();
+        /* Add timezone stuff here */
+        thd->one_shot_set= 0;
+      }
+    }
   if (res < 0)
     send_error(thd,thd->killed ? ER_SERVER_SHUTDOWN : 0);
 
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 6a40dc3c23a..04aab392285 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -316,6 +316,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token	NUM
 %token	OFFSET_SYM
 %token	ON
+%token  ONE_SHOT_SYM
 %token	OPEN_SYM
 %token	OPTION
 %token	OPTIONALLY
@@ -5002,6 +5003,7 @@ keyword:
 	| NVARCHAR_SYM		{}
 	| OFFSET_SYM		{}
 	| OLD_PASSWORD		{}
+	| ONE_SHOT_SYM		{}
 	| OPEN_SYM		{}
 	| PACK_KEYS_SYM		{}
 	| PARTIAL		{}
@@ -5088,6 +5090,7 @@ set:
 	  lex->sql_command= SQLCOM_SET_OPTION;
 	  lex->option_type=OPT_SESSION;
 	  lex->var_list.empty();
+          lex->one_shot_set= 0;
 	}
 	option_value_list
 	{}
@@ -5106,6 +5109,7 @@ option_type:
 	| GLOBAL_SYM	{ Lex->option_type= OPT_GLOBAL; }
 	| LOCAL_SYM	{ Lex->option_type= OPT_SESSION; }
 	| SESSION_SYM	{ Lex->option_type= OPT_SESSION; }
+	| ONE_SHOT_SYM	{ Lex->option_type= OPT_SESSION; Lex->one_shot_set= 1; }
 	;
 
 opt_var_type: