bzr commit into mysql-6.0-runtime branch (staale.smedseng:2705) Bug#22891

[staale.smedseng]

#At file:///home/ss156133/z/b22891/

 2705 staale.smedseng@stripped	2008-09-03
      A fix for Bug#22891 "session level max_allowed_packet can be set 
      but is ignored". 
      
      This patch makes @@session.max_allowed_packed read-only as suggested 
      in the bug report. The user will have to use SET GLOBAL (and reconnect)
      to alter the value of max_allowed_packet. A new error code 
      ER_SESSION_COUNTERPART_IS_READONLY is introduced.
      
      The implementation introduces a new class sys_var_max_allowed_packet,
      inherited from sys_var_thd. Tests are modified accordingly.
modified:
  mysql-test/r/func_compress.result
  mysql-test/r/max_allowed_packet_basic.result
  mysql-test/r/max_allowed_packet_func.result
  mysql-test/r/packet.result
  mysql-test/r/union.result
  mysql-test/r/variables.result
  mysql-test/t/func_compress.test
  mysql-test/t/innodb_bug34300.test
  mysql-test/t/max_allowed_packet_basic.test
  mysql-test/t/max_allowed_packet_func.test
  mysql-test/t/packet.test
  mysql-test/t/union.test
  mysql-test/t/variables.test
  sql/set_var.cc
  sql/set_var.h
  sql/share/errmsg.txt

per-file messages:
  mysql-test/r/func_compress.result
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/r/max_allowed_packet_basic.result
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/r/max_allowed_packet_func.result
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/r/packet.result
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/r/union.result
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/r/variables.result
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/t/func_compress.test
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/t/innodb_bug34300.test
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/t/max_allowed_packet_basic.test
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/t/max_allowed_packet_func.test
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/t/packet.test
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/t/union.test
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  mysql-test/t/variables.test
    Modified tests to honor error code for read-only variable max_allowed_packet,
    and using SET GLOBAL and reconnecting where appropriate.
  sql/set_var.cc
    Added new class sys_var_max_allowed_packed inherited from sys_var_thd to
    implement the read-only aspect of max_allowed_packet.
  sql/set_var.h
    Added new class sys_var_max_allowed_packed inherited from sys_var_thd to
    implement the read-only aspect of max_allowed_packet.
  sql/share/errmsg.txt
    New error message indicating read-only variable.
=== modified file 'mysql-test/r/func_compress.result'
--- a/mysql-test/r/func_compress.result	2008-07-14 12:49:19 +0000
+++ b/mysql-test/r/func_compress.result	2008-09-03 13:15:00 +0000
@@ -68,7 +68,7 @@ Warnings:
 Warning	1259	ZLIB: Input data corrupted
 Warning	1256	Uncompressed data size too large; the maximum size is 1048576 (probably,
length of uncompressed data was corrupted)
 drop table t1;
-set @@max_allowed_packet=1048576*100;
+set global max_allowed_packet=1048576*100;
 select compress(repeat('aaaaaaaaaa', IF(XXX, 10, 10000000))) is null;
 compress(repeat('aaaaaaaaaa', IF(XXX, 10, 10000000))) is null
 0

=== modified file 'mysql-test/r/max_allowed_packet_basic.result'
--- a/mysql-test/r/max_allowed_packet_basic.result	2008-04-10 13:14:28 +0000
+++ b/mysql-test/r/max_allowed_packet_basic.result	2008-09-03 13:15:00 +0000
@@ -15,7 +15,7 @@ SELECT @@global.max_allowed_packet;
 @@global.max_allowed_packet
 1048576
 SET @@session.max_allowed_packet = 20000;
-SET @@session.max_allowed_packet = DEFAULT;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
 1048576
@@ -24,10 +24,6 @@ SET @@global.max_allowed_packet = DEFAUL
 SELECT @@global.max_allowed_packet = 1048576;
 @@global.max_allowed_packet = 1048576
 1
-SET @@session.max_allowed_packet = DEFAULT;
-SELECT @@session.max_allowed_packet = 1048576;
-@@session.max_allowed_packet = 1048576
-1
 '#--------------------FN_DYNVARS_070_03-------------------------#'
 SET @@global.max_allowed_packet = 1024;
 SELECT @@global.max_allowed_packet;
@@ -48,25 +44,30 @@ SELECT @@global.max_allowed_packet;
 1073740800
 '#--------------------FN_DYNVARS_070_04-------------------------#'
 SET @@session.max_allowed_packet = 1024;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1024
+1048576
 SET @@session.max_allowed_packet = 1025;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1024
+1048576
 SET @@session.max_allowed_packet = 65535;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-64512
+1048576
 SET @@session.max_allowed_packet = 1073741824;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1073741824
+1048576
 SET @@session.max_allowed_packet = 1073741823;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1073740800
+1048576
 '#------------------FN_DYNVARS_070_05-----------------------#'
 SET @@global.max_allowed_packet = 0;
 Warnings:
@@ -103,37 +104,33 @@ SELECT @@global.max_allowed_packet;
 @@global.max_allowed_packet
 1073741824
 SET @@session.max_allowed_packet = 0;
-Warnings:
-Warning	1292	Truncated incorrect max_allowed_packet value: '0'
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1024
+1048576
 SET @@session.max_allowed_packet = 1023;
-Warnings:
-Warning	1292	Truncated incorrect max_allowed_packet value: '1023'
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1024
+1048576
 SET @@session.max_allowed_packet = -2;
-Warnings:
-Warning	1292	Truncated incorrect max_allowed_packet value: '0'
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1024
+1048576
 SET @@session.max_allowed_packet = 65530.34.;
 ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to
your MySQL server version for the right syntax to use near '.' at line 1
 SET @@session.max_allowed_packet = 10737418241;
-Warnings:
-Warning	1292	Truncated incorrect max_allowed_packet value: '10737418241'
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1073741824
+1048576
 'Bug # 34837: Errors are not coming on assigning invalid values to variable';
 SET @@session.max_allowed_packet = test;
 ERROR 42000: Incorrect argument type to variable 'max_allowed_packet'
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
-1073741824
+1048576
 '#------------------FN_DYNVARS_070_06-----------------------#'
 SELECT @@global.max_allowed_packet = VARIABLE_VALUE 
 FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES 
@@ -166,6 +163,7 @@ SELECT @@max_allowed_packet = @@global.m
 0
 '#---------------------FN_DYNVARS_070_10----------------------#'
 SET @@max_allowed_packet = 100000;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@max_allowed_packet = @@local.max_allowed_packet;
 @@max_allowed_packet = @@local.max_allowed_packet
 1
@@ -174,9 +172,10 @@ SELECT @@local.max_allowed_packet = @@se
 1
 '#---------------------FN_DYNVARS_070_11----------------------#'
 SET max_allowed_packet = 1024;
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 SELECT @@max_allowed_packet;
 @@max_allowed_packet
-1024
+1048576
 SELECT local.max_allowed_packet;
 ERROR 42S02: Unknown table 'local' in field list
 SELECT session.max_allowed_packet;
@@ -187,7 +186,6 @@ SET @@global.max_allowed_packet = @start
 SELECT @@global.max_allowed_packet;
 @@global.max_allowed_packet
 1048576
-SET @@session.max_allowed_packet = @start_session_value;
 SELECT @@session.max_allowed_packet;
 @@session.max_allowed_packet
 1048576

=== modified file 'mysql-test/r/max_allowed_packet_func.result'
--- a/mysql-test/r/max_allowed_packet_func.result	2008-04-18 09:38:41 +0000
+++ b/mysql-test/r/max_allowed_packet_func.result	2008-09-03 13:15:00 +0000
@@ -10,24 +10,7 @@ name BLOB
 '#--------------------FN_DYNVARS_070_01-------------------------#'
 ## Setting value of max_allowed packet and net_buffer_length to 1024 ## 
 SET @@session.max_allowed_packet = 1024;
-SET @@session.net_buffer_length = 1024;
-SELECT @@session.max_allowed_packet;
-@@session.max_allowed_packet
-1024
-SELECT @@session.net_buffer_length;
-@@session.net_buffer_length
-1024
-## Inserting and fetching data of length greater than 1024 ##
-INSERT into t1(name) values("aaassssssssddddddddffffffgggggggg,
askdlfjalsdkjfalksdjflaksdjfalkjdflaksjdflakjdflajsflajflajdfalsjfdlajfladjslfajdflajdsflajsflakjsdfla;kjflsdjkf;aljfa;lkdsfjla;sjlkajffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllakjsdffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa;;;;;;;;;;;;;;;;;;;;;;;;;;;dsklfjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj!
 jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjkljffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffdkskkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk");
-SELECT length("aaaaaasssssssssssdddddddfffffgggg,
askdlfjalsdkjfalksdjflaksdjfalkjdflaksjdflakjdflajsflajflajdfalsjfdlajfladjslfajdflajdsflajsflakjsdfla;kjflsdjkf;aljfa;lkdsfjla;sjlkajffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllakjsdffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa;;;;;;;;;;;;;;;;;;;;;;;;;;;dsklfjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj!
 jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjkljffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffdkskkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk")
as len;
-len
-1470
-## Verifying record in table t1 ##
-SELECT * from t1;
-id	name
-1	aaassssssssddddddddffffffgggggggg,
askdlfjalsdkjfalksdjflaksdjfalkjdflaksjdflakjdflajsflajflajdfalsjfdlajfladjslfajdflajdsflajsflakjsdfla;kjflsdjkf;aljfa;lkdsfjla;sjlkajffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllakjsdffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa;;;;;;;;;;;;;;;;;;;;;;;;;;;dsklfjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj!
 jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjkljffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffdkskkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk
-'Bug#35381: Error is not coming on inserting and fetching data of length'
-'greater than max_allowed_packet size at session level';
+ERROR HY000: Session variable max_allowed_packet is a constant. Use SET GLOBAL to assign
the global value
 '#--------------------FN_DYNVARS_070_02-------------------------#'
 ## Setting value of max_allowed packet and net_buffer_length to 1024 ## 
 SET @@global.max_allowed_packet = 1024;

=== modified file 'mysql-test/r/packet.result'
--- a/mysql-test/r/packet.result	2007-11-30 05:32:04 +0000
+++ b/mysql-test/r/packet.result	2008-09-03 13:15:00 +0000
@@ -1,35 +1,27 @@
 set global max_allowed_packet=100;
 Warnings:
 Warning	1292	Truncated incorrect max_allowed_packet value: '100'
-set max_allowed_packet=100;
-Warnings:
-Warning	1292	Truncated incorrect max_allowed_packet value: '100'
 set global net_buffer_length=100;
 Warnings:
 Warning	1292	Truncated incorrect net_buffer_length value: '100'
-set net_buffer_length=100;
-Warnings:
-Warning	1292	Truncated incorrect net_buffer_length value: '100'
 SELECT
length("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") as len;
 len
 1024
 select repeat('a',2000);
 repeat('a',2000)
-NULL
-Warnings:
-Warning	1301	Result of repeat() was larger than max_allowed_packet (1024) - truncated
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!
 aaaaaaaaaaaaaaaaaaaaaaaa
 select @@net_buffer_length, @@max_allowed_packet;
 @@net_buffer_length	@@max_allowed_packet
 1024	1024
 SELECT
length("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") as len;
 ERROR 08S01: Got a packet bigger than 'max_allowed_packet' bytes
 set global max_allowed_packet=default;
-set max_allowed_packet=default;
 set global net_buffer_length=default;
-set net_buffer_length=default;
 SELECT
length("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
as len;
 len
 100
 select length(repeat('a',2000));
 length(repeat('a',2000))
-2000
+NULL
+Warnings:
+Warning	1301	Result of repeat() was larger than max_allowed_packet (1024) - truncated

=== modified file 'mysql-test/r/union.result'
--- a/mysql-test/r/union.result	2008-05-13 15:15:40 +0000
+++ b/mysql-test/r/union.result	2008-09-03 13:15:00 +0000
@@ -1301,10 +1301,10 @@ t3	CREATE TABLE `t3` (
   `left(a,100000000)` longtext
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop tables t1,t2,t3;
-SELECT @tmp_max:= @@max_allowed_packet;
-@tmp_max:= @@max_allowed_packet
+SELECT @tmp_max:= @@global.max_allowed_packet;
+@tmp_max:= @@global.max_allowed_packet
 1048576
-SET max_allowed_packet=25000000;
+SET @@global.max_allowed_packet=25000000;
 CREATE TABLE t1 (a mediumtext);
 CREATE TABLE t2 (b varchar(20));
 INSERT INTO t1 VALUES ('a');
@@ -1342,7 +1342,7 @@ t3	CREATE TABLE `t3` (
   `a` varbinary(510) DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLES t1,t2,t3;
-SET max_allowed_packet:= @tmp_max;
+SET @@global.max_allowed_packet:= @tmp_max;
 create table t1 ( id int not null auto_increment, primary key (id), col1 int);
 insert into t1 (col1) values (2),(3),(4),(5),(6);
 select 99 union all select id from t1 order by 1;

=== modified file 'mysql-test/r/variables.result'
--- a/mysql-test/r/variables.result	2008-05-29 12:56:51 +0000
+++ b/mysql-test/r/variables.result	2008-09-03 13:15:00 +0000
@@ -461,7 +461,7 @@ select @@long_query_time;
 @@long_query_time
 100.000001
 set low_priority_updates=1;
-set max_allowed_packet=100;
+set global max_allowed_packet=100;
 Warnings:
 Warning	1292	Truncated incorrect max_allowed_packet value: '100'
 set global max_binlog_cache_size=100;

=== modified file 'mysql-test/t/func_compress.test'
--- a/mysql-test/t/func_compress.test	2006-10-13 14:09:22 +0000
+++ b/mysql-test/t/func_compress.test	2008-09-03 13:15:00 +0000
@@ -43,8 +43,11 @@ drop table t1;
 # note that when LOW_MEMORY is set the "test" below is meaningless
 #
 
-set @@max_allowed_packet=1048576*100;
+set global max_allowed_packet=1048576*100;
 --replace_result "''" XXX "'1'" XXX
+
+# reconnect to make the new max packet size take effect
+--connect (newconn, localhost, root,,)
 eval select compress(repeat('aaaaaaaaaa', IF('$LOW_MEMORY', 10, 10000000))) is null;
 
 #

=== modified file 'mysql-test/t/innodb_bug34300.test'
--- a/mysql-test/t/innodb_bug34300.test	2008-06-12 00:08:07 +0000
+++ b/mysql-test/t/innodb_bug34300.test	2008-09-03 13:15:00 +0000
@@ -8,7 +8,9 @@
 -- disable_query_log
 -- disable_result_log
 
-SET @@max_allowed_packet=16777216;
+# set packet size and reconnect 
+SET global max_allowed_packet=16777216;
+--connect (newconn, localhost, root,,)
 
 DROP TABLE IF EXISTS bug34300;
 CREATE TABLE bug34300 (

=== modified file 'mysql-test/t/max_allowed_packet_basic.test'
--- a/mysql-test/t/max_allowed_packet_basic.test	2008-04-10 13:14:28 +0000
+++ b/mysql-test/t/max_allowed_packet_basic.test	2008-09-03 13:15:00 +0000
@@ -49,8 +49,8 @@ SET @@global.max_allowed_packet = 1000;
 SET @@global.max_allowed_packet = DEFAULT;
 SELECT @@global.max_allowed_packet;
 
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 20000;
-SET @@session.max_allowed_packet = DEFAULT;
 SELECT @@session.max_allowed_packet;
 
 
@@ -62,9 +62,6 @@ SELECT @@session.max_allowed_packet;
 SET @@global.max_allowed_packet = DEFAULT;
 SELECT @@global.max_allowed_packet = 1048576;
 
-SET @@session.max_allowed_packet = DEFAULT;
-SELECT @@session.max_allowed_packet = 1048576;
-
 
 --echo '#--------------------FN_DYNVARS_070_03-------------------------#'
 ############################################################################
@@ -86,14 +83,19 @@ SELECT @@global.max_allowed_packet;
 # Change the value of max_allowed_packet to a valid value for SESSION Scope #
 #############################################################################
  
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 1024;
 SELECT @@session.max_allowed_packet;
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 1025;
 SELECT @@session.max_allowed_packet;
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 65535;
 SELECT @@session.max_allowed_packet;
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 1073741824;
 SELECT @@session.max_allowed_packet;
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 1073741823;
 SELECT @@session.max_allowed_packet;
 
@@ -118,14 +120,18 @@ SELECT @@global.max_allowed_packet;
 SET @@global.max_allowed_packet = test;
 SELECT @@global.max_allowed_packet;
 
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 0;
 SELECT @@session.max_allowed_packet;
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 1023;
 SELECT @@session.max_allowed_packet;
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = -2;
 SELECT @@session.max_allowed_packet;
 --Error ER_PARSE_ERROR
 SET @@session.max_allowed_packet = 65530.34.;
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 10737418241;
 SELECT @@session.max_allowed_packet;
 --echo 'Bug # 34837: Errors are not coming on assigning invalid values to variable';
@@ -140,11 +146,11 @@ SELECT @@session.max_allowed_packet;
 #   Check if the value in GLOBAL Table matches value in variable   #
 ####################################################################
 
-
 SELECT @@global.max_allowed_packet = VARIABLE_VALUE 
 FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES 
 WHERE VARIABLE_NAME='max_allowed_packet';
 
+
 --echo '#------------------FN_DYNVARS_070_07-----------------------#'
 ####################################################################
 #  Check if the value in SESSION Table matches value in variable   #
@@ -180,6 +186,7 @@ SELECT @@max_allowed_packet = @@global.m
 #    Check if accessing variable with SESSION,LOCAL and without SCOPE points to same
session variable  #
 ########################################################################################################
 
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@max_allowed_packet = 100000;
 SELECT @@max_allowed_packet = @@local.max_allowed_packet;
 SELECT @@local.max_allowed_packet = @@session.max_allowed_packet;
@@ -190,6 +197,7 @@ SELECT @@local.max_allowed_packet = @@se
 #   Check if max_allowed_packet can be accessed with and without @@ sign    #
 #############################################################################
 
+--Error ER_SESSION_COUNTERPART_IS_READONLY
 SET max_allowed_packet = 1024;
 SELECT @@max_allowed_packet;
 --Error ER_UNKNOWN_TABLE
@@ -206,7 +214,6 @@ SELECT max_allowed_packet = @@session.ma
 
 SET @@global.max_allowed_packet = @start_global_value;
 SELECT @@global.max_allowed_packet;
-SET @@session.max_allowed_packet = @start_session_value;
 SELECT @@session.max_allowed_packet;
 
 

=== modified file 'mysql-test/t/max_allowed_packet_func.test'
--- a/mysql-test/t/max_allowed_packet_func.test	2008-04-23 09:36:17 +0000
+++ b/mysql-test/t/max_allowed_packet_func.test	2008-09-03 13:15:00 +0000
@@ -43,26 +43,14 @@ name BLOB
 
 --echo '#--------------------FN_DYNVARS_070_01-------------------------#'
 ###############################################################################
-#    Setting initial value of max_allowed_packet to 1024 at session level and
-#    verifying its behavior after inserting data greater than 1024 bytes     
+#    Setting initial value of max_allowed_packet to 1024 at session level 
+#    should result in an error (session variable is readonly)
 ###############################################################################
 
 --echo ## Setting value of max_allowed packet and net_buffer_length to 1024 ## 
+--error ER_SESSION_COUNTERPART_IS_READONLY
 SET @@session.max_allowed_packet = 1024;
-SET @@session.net_buffer_length = 1024;
-SELECT @@session.max_allowed_packet;
-SELECT @@session.net_buffer_length;
-
---echo ## Inserting and fetching data of length greater than 1024 ##
-INSERT into t1(name) values("aaassssssssddddddddffffffgggggggg,
askdlfjalsdkjfalksdjflaksdjfalkjdflaksjdflakjdflajsflajflajdfalsjfdlajfladjslfajdflajdsflajsflakjsdfla;kjflsdjkf;aljfa;lkdsfjla;sjlkajffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllakjsdffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa;;;;;;;;;;;;;;;;;;;;;;;;;;;dsklfjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj!
 jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjkljffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffdkskkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk");
-
-SELECT length("aaaaaasssssssssssdddddddfffffgggg,
askdlfjalsdkjfalksdjflaksdjfalkjdflaksjdflakjdflajsflajflajdfalsjfdlajfladjslfajdflajdsflajsflakjsdfla;kjflsdjkf;aljfa;lkdsfjla;sjlkajffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllakjsdffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa;;;;;;;;;;;;;;;;;;;;;;;;;;;dsklfjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj!
 jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjkljffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffdkskkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk")
as len;
-
---echo ## Verifying record in table t1 ##
-SELECT * from t1;
 
---echo 'Bug#35381: Error is not coming on inserting and fetching data of length'
---echo 'greater than max_allowed_packet size at session level';
 
 --echo '#--------------------FN_DYNVARS_070_02-------------------------#'
 ###############################################################################

=== modified file 'mysql-test/t/packet.test'
--- a/mysql-test/t/packet.test	2005-08-04 00:38:55 +0000
+++ b/mysql-test/t/packet.test	2008-09-03 13:15:00 +0000
@@ -8,30 +8,24 @@
 # Check protocol handling
 #
 
-connect (con1,localhost,root,,);
-
-connection con1;
+# setting values below minimum threshold of 1024 will cause truncating
 set global max_allowed_packet=100;
-set max_allowed_packet=100;
 set global net_buffer_length=100;
-set net_buffer_length=100;
-# Have to be > 1024 as min value of net_buffer_length is 1024
+
+# is not yet in effect
 SELECT
length("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") as len;
-# Should return NULL as 2000 is bigger than max_allowed_packet
 select repeat('a',2000);
 
 #
-# Connection 2 should get error for too big packets
+# Connection 1 should get error for too big packets
 #
-connect (con2,localhost,root,,);
-connection con2;
+connect (con1,localhost,root,,);
+connection con1;
 select @@net_buffer_length, @@max_allowed_packet;
 --error 1153
 SELECT
length("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") as len;
 set global max_allowed_packet=default;
-set max_allowed_packet=default;
 set global net_buffer_length=default;
-set net_buffer_length=default;
 SELECT
length("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
as len;
 select length(repeat('a',2000));
 

=== modified file 'mysql-test/t/union.test'
--- a/mysql-test/t/union.test	2008-05-13 15:15:40 +0000
+++ b/mysql-test/t/union.test	2008-09-03 13:15:00 +0000
@@ -802,8 +802,10 @@ drop tables t1,t2,t3;
 # exceeds mediumtext maximum length
 #
 
-SELECT @tmp_max:= @@max_allowed_packet;
-SET max_allowed_packet=25000000;
+SELECT @tmp_max:= @@global.max_allowed_packet;
+SET @@global.max_allowed_packet=25000000;
+# switching connection to allow the new max_allowed_packet take effect
+--connect (newconn, localhost, root,,)
 CREATE TABLE t1 (a mediumtext);
 CREATE TABLE t2 (b varchar(20));
 INSERT INTO t1 VALUES ('a');
@@ -825,7 +827,9 @@ INSERT INTO t1 VALUES ('a');
 CREATE TABLE t3 SELECT REPEAT(a,2) AS a FROM t1 UNION SELECT b FROM t2;
 SHOW CREATE TABLE t3;
 DROP TABLES t1,t2,t3;
-SET max_allowed_packet:= @tmp_max;
+--connection default
+SET @@global.max_allowed_packet:= @tmp_max;
+--disconnect newconn
 
 #
 # Bug #10032 Bug in parsing UNION with ORDER BY when one node does not use FROM

=== modified file 'mysql-test/t/variables.test'
--- a/mysql-test/t/variables.test	2008-06-17 20:04:19 +0000
+++ b/mysql-test/t/variables.test	2008-09-03 13:15:00 +0000
@@ -274,7 +274,7 @@ select @@long_query_time;
 set long_query_time=100.000001;
 select @@long_query_time;
 set low_priority_updates=1;
-set max_allowed_packet=100;
+set global max_allowed_packet=100;
 set global max_binlog_cache_size=100;
 set global max_binlog_size=100;
 set global max_connect_errors=100;

=== modified file 'sql/set_var.cc'
--- a/sql/set_var.cc	2008-08-08 01:33:43 +0000
+++ b/sql/set_var.cc	2008-09-03 13:15:00 +0000
@@ -294,8 +294,16 @@ static sys_var_thd_bool	sys_sql_low_prio
 						     &SV::low_priority_updates,
 						     fix_low_priority_updates);
 #endif
-static sys_var_thd_ulong	sys_max_allowed_packet(&vars, "max_allowed_packet",
+/*@ss static sys_var_thd_ulong	sys_max_allowed_packet(&vars, "max_allowed_packet",
 					       &SV::max_allowed_packet);
+static uchar *get_max_allowed_packet(THD *thd)
+{
+  return (uchar*) &thd->variables.max_allowed_packet;
+}
+static sys_var_readonly	sys_max_allowed_packet(&vars, "max_allowed_packet",
OPT_SESSION,
+                                               SHOW_LONG, get_max_allowed_packet); */
+static sys_var_max_allowed_packet  sys_max_allowed_packet(&vars,
"max_allowed_packet");					       
+
 static sys_var_long_ptr	sys_max_binlog_cache_size(&vars, "max_binlog_cache_size",
 						  &max_binlog_cache_size);
 static sys_var_long_ptr	sys_max_binlog_size(&vars, "max_binlog_size",
@@ -2835,6 +2843,72 @@ uchar *sys_var_max_user_conn::value_ptr(
 }
 
 
+bool sys_var_max_allowed_packet::check(THD *thd, set_var *var)
+{
+  if (var->type != OPT_GLOBAL)
+  {
+    /*
+      The session value of max_allowed_packet is read-only.
+    */
+    my_error(ER_SESSION_COUNTERPART_IS_READONLY, MYF(0), name);
+    return TRUE;
+  }
+
+  return get_unsigned(thd, var);
+}
+
+bool sys_var_max_allowed_packet::update(THD *thd, set_var *var)
+{
+  if (var->type != OPT_GLOBAL)
+  {
+    // the session value of max_allowed_packet is read-only
+    my_error(ER_SESSION_COUNTERPART_IS_READONLY, MYF(0), name);
+    return TRUE;
+  }
+  
+  ulonglong tmp= var->save_result.ulonglong_value;
+
+  /* Don't use bigger value than given with --maximum-variable-name=.. */
+  if ((ulong) tmp > max_system_variables.max_allowed_packet)
+  {
+    throw_bounds_warning(thd, TRUE, TRUE, name, (longlong) tmp);
+    tmp= max_system_variables.max_allowed_packet;
+  }
+
+  if (option_limits)
+    tmp= (ulong) fix_unsigned(thd, tmp, option_limits);
+#if SIZEOF_LONG < SIZEOF_LONG_LONG
+  else if (tmp > ULONG_MAX)
+  {
+    tmp= ULONG_MAX;
+    throw_bounds_warning(thd, TRUE, TRUE, name, (longlong)
var->save_result.ulonglong_value);
+  }
+#endif
+
+  global_system_variables.max_allowed_packet= (ulong) tmp;
+  return FALSE;
+}
+
+
+void sys_var_max_allowed_packet::set_default(THD *thd, enum_var_type type)
+{
+  DBUG_ASSERT(type == OPT_GLOBAL);
+  my_bool not_used;
+  global_system_variables.max_allowed_packet=
+    (ulong) getopt_ull_limit_value((ulong) option_limits->def_value,
+                                     option_limits, &not_used);
+}
+
+
+uchar *sys_var_max_allowed_packet::value_ptr(THD *thd, enum_var_type type,
+                                       LEX_STRING *base)
+{
+  if (type != OPT_GLOBAL)
+    return (uchar*) &(thd->variables.max_allowed_packet);
+  return (uchar*) &(global_system_variables.max_allowed_packet);
+}
+
+
 bool sys_var_thd_lc_time_names::check(THD *thd, set_var *var)
 {
   MY_LOCALE *locale_match;

=== modified file 'sql/set_var.h'
--- a/sql/set_var.h	2008-07-09 07:12:43 +0000
+++ b/sql/set_var.h	2008-09-03 13:15:00 +0000
@@ -1058,6 +1058,24 @@ public:
 };
 
 
+class sys_var_max_allowed_packet : public sys_var_thd
+{
+public:
+  sys_var_max_allowed_packet(sys_var_chain *chain, const char *name_arg):
+    sys_var_thd(name_arg)
+  { chain_sys_var(chain); }
+  bool check(THD *thd, set_var *var);
+  bool update(THD *thd, set_var *var);
+  bool check_default(enum_var_type type)
+  {
+    return type != OPT_GLOBAL || !option_limits;
+  }
+  void set_default(THD *thd, enum_var_type type);
+  SHOW_TYPE show_type() { return SHOW_INT; }
+  uchar *value_ptr(THD *thd, enum_var_type type, LEX_STRING *base);
+};
+
+
 class sys_var_microseconds :public sys_var_thd
 {
   ulonglong SV::*offset;

=== modified file 'sql/share/errmsg.txt'
--- a/sql/share/errmsg.txt	2008-08-06 14:39:03 +0000
+++ b/sql/share/errmsg.txt	2008-09-03 13:15:00 +0000
@@ -6372,3 +6372,5 @@ ER_BACKUP_OBTAIN_NAME_LOCK_FAILED
   eng "Restore failed to obtain the name locks on the tables."
 ER_BACKUP_RELEASE_NAME_LOCK_FAILED
   eng "Restore failed to release the name locks on the tables."
+ER_SESSION_COUNTERPART_IS_READONLY
+  eng "Session variable %s is a constant. Use SET GLOBAL to assign the global value"