Merge gbichot@213.136.52.20:/home/bk/mysql-4.1

into mysql.com:/home/mysql_src/mysql-4.1

mysql-test/r/rpl_user_variables.result

@@ -21,6 +21,7 @@ set @q:='abc';
 insert t1 values (@q), (@q:=concat(@q, 'n1')), (@q:=concat(@q, 'n2'));
 set @a:=5;
 insert into t1 values (@a),(@a);
+insert into t1 values (@a),(@a),(@a*5);
 select * from t1;
 n
 12345678901234
@@ -45,6 +46,36 @@ abcn1
 abcn1n2
 5
 5
+NULL
+NULL
+NULL
+select * from t1;
+n
+12345678901234
+-12345678901234
+0
+-1
+12.5
+-12.5
+This is a test
+
+abc'def
+abc\def
+abc'def
+NULL
+NULL
+0
+1
+2
+5
+abc
+abcn1
+abcn1n2
+5
+5
+NULL
+NULL
+NULL
 show binlog events from 141;
 Log_name	Pos	Event_type	Server_id	Orig_log_pos	Info
 slave-bin.000001	141	User var	2	141	@i1=12345678901234
@@ -63,13 +94,16 @@ slave-bin.000001	719	User var	2	719	@s5='abc'def'
 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)
-slave-bin.000001	939	Query	1	939	use `test`; insert into t1 values (@n2)
-slave-bin.000001	1001	Query	1	1001	use `test`; insert into t1 values (@a:=0), (@a:=@a+1), (@a:=@a+1)
-slave-bin.000001	1089	User var	2	1089	@a=2
-slave-bin.000001	1131	Query	1	1131	use `test`; insert into t1 values (@a+(@b:=@a+1))
-slave-bin.000001	1203	User var	2	1203	@q='abc'
-slave-bin.000001	1240	Query	1	1240	use `test`; insert t1 values (@q), (@q:=concat(@q, 'n1')), (@q:=concat(@q, 'n2'))
-slave-bin.000001	1344	User var	2	1344	@a=5
-slave-bin.000001	1386	Query	1	1386	use `test`; insert into t1 values (@a),(@a)
+slave-bin.000001	939	User var	2	939	@n2=NULL
+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	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)
+slave-bin.000001	1478	User var	2	1478	@a=NULL
+slave-bin.000001	1503	Query	1	1503	use `test`; insert into t1 values (@a),(@a),(@a*5)
 drop table t1;
 stop slave;

mysql-test/r/user_var.result

@@ -5,6 +5,10 @@ set @a := connection_id() + 3;
 select @a - connection_id();
 @a - connection_id()
 3
+set @b := 1;
+select @b;
+@b
+1
 CREATE TABLE t1 ( i int not null, v int not null,index (i));
 insert into t1 values (1,1),(1,3),(2,1);
 create table t2 (i int not null, unique (i));

mysql-test/t/rpl_user_variables.test

@@ -29,13 +29,16 @@ insert into t1 values (@i1), (@i2), (@i3), (@i4);
 insert into t1 values (@r1), (@r2);
 insert into t1 values (@s1), (@s2), (@s3), (@s4), (@s5);
 insert into t1 values (@n1);
-insert into t1 values (@n2);
+insert into t1 values (@n2); # not explicitely set before
 insert into t1 values (@a:=0), (@a:=@a+1), (@a:=@a+1);
 insert into t1 values (@a+(@b:=@a+1));
 set @q:='abc';
 insert t1 values (@q), (@q:=concat(@q, 'n1')), (@q:=concat(@q, 'n2'));
 set @a:=5;
 insert into t1 values (@a),(@a);
+connection master1; # see if variable is reset in binlog when thread changes
+insert into t1 values (@a),(@a),(@a*5);
+select * from t1;
 save_master_pos;
 connection slave;
 sync_with_master;

mysql-test/t/user_var.test

@@ -8,6 +8,9 @@ set @a := foo;
 set @a := connection_id() + 3;
 select @a - connection_id();
 
+set @b := 1;
+select @b;
+
 # Check using and setting variables with SELECT DISTINCT
 
 CREATE TABLE t1 ( i int not null, v int not null,index (i));

sql/item_func.cc

@@ -2071,6 +2071,16 @@ static user_var_entry *get_variable(HASH *hash, LEX_STRING &name,
     entry->value=0;
     entry->length=0;
     entry->update_query_id=0;
+    /*
+      If we are here, we were called from a SET or a query which sets a
+      variable. Imagine it is this:
+      INSERT INTO t SELECT @a:=10, @a:=@a+1.
+      Then when we have a Item_func_get_user_var (because of the @a+1) so we
+      think we have to write the value of @a to the binlog. But before that,
+      we have a Item_func_set_user_var to create @a (@a:=10), in this we mark
+      the variable as "already logged" (line below) so that it won't be logged
+      by Item_func_get_user_var (because that's not necessary).
+    */
     entry->used_query_id=current_thd->query_id;
     entry->type=STRING_RESULT;
     memcpy(entry->name.str, name.str, name.length+1);
@@ -2083,7 +2093,10 @@ static user_var_entry *get_variable(HASH *hash, LEX_STRING &name,
   return entry;
 }
 
-
+/*
+  When a user variable is updated (in a SET command or a query like SELECT @a:=
+  ).
+*/
 
 bool Item_func_set_user_var::fix_fields(THD *thd, TABLE_LIST *tables,
 					Item **ref)
@@ -2093,6 +2106,11 @@ bool Item_func_set_user_var::fix_fields(THD *thd, TABLE_LIST *tables,
       !(entry= get_variable(&thd->user_vars, name, 1)))
     return 1;
   entry->type= cached_result_type;
+  /* 
+     Remember the last query which updated it, this way a query can later know
+     if this variable is a constant item in the query (it is if update_query_id
+     is different from query_id).
+  */
   entry->update_query_id=thd->query_id;
   return 0;
 }
@@ -2315,19 +2333,58 @@ longlong Item_func_get_user_var::val_int()
 }
 
 
+/*
+  When a user variable is invoked from an update query (INSERT, UPDATE etc),
+  stores this variable and its value in thd->user_var_events, so that it can be
+  written to the binlog (will be written just before the query is written, see
+  log.cc).
+*/
+
 void Item_func_get_user_var::fix_length_and_dec()
 {
-  BINLOG_USER_VAR_EVENT *user_var_event;
   THD *thd=current_thd;
+  BINLOG_USER_VAR_EVENT *user_var_event;
   maybe_null=1;
   decimals=NOT_FIXED_DEC;
   max_length=MAX_BLOB_WIDTH;
 
-  if ((var_entry= get_variable(&thd->user_vars, name, 0)))
-  {
-    if (opt_bin_log && is_update_query(thd->lex.sql_command) &&
-	var_entry->used_query_id != thd->query_id)
+  var_entry= get_variable(&thd->user_vars, name, 0);
+
+  if (!(opt_bin_log && is_update_query(thd->lex.sql_command)))
+    return;
+
+  if (!var_entry)
   {
+    /*
+      If the variable does not exist, it's NULL, but we want to create it so
+      that it gets into the binlog (if it didn't, the slave could be
+      influenced by a variable of the same name previously set by another
+      thread).
+      We create it like if it had been explicitely set with SET before.
+      The 'new' mimicks what sql_yacc.yy does when 'SET @a=10;'.
+      sql_set_variables() is what is called from 'case SQLCOM_SET_OPTION'
+      in dispatch_command()). Instead of building a one-element list to pass to
+      sql_set_variables(), we could instead manually call check() and update();
+      this would save memory and time; but calling sql_set_variables() makes one
+      unique place to maintain (sql_set_variables()). 
+    */
+
+    List<set_var_base> tmp_var_list;
+    tmp_var_list.push_back(new set_var_user(new Item_func_set_user_var(name,
+                                                                       new Item_null())));
+    if (sql_set_variables(thd, &tmp_var_list)) /* this will create the variable */
+      goto err;
+    if (!(var_entry= get_variable(&thd->user_vars, name, 0)))
+      goto err;
+  }
+  /* 
+     If this variable was already stored in user_var_events by this query
+     (because it's used in more than one place in the query), don't store
+     it.
+  */
+  else if (var_entry->used_query_id == thd->query_id)
+    return;
+
   uint size;
   /*
     First we need to store value of var_entry, when the next situation
@@ -2357,11 +2414,11 @@ void Item_func_get_user_var::fix_length_and_dec()
     memcpy(user_var_event->value, var_entry->value,
            var_entry->length);
   }
+  /* Mark that this variable has been used by this query */
   var_entry->used_query_id= thd->query_id;
   if (insert_dynamic(&thd->user_var_events, (gptr) &user_var_event))
     goto err;
-    }
-  }
+
   return;
 
 err: