MySQL Bugs: #32580: mysqlbinlog cannot read binlog event generated by user variable usage

Bug #32580	mysqlbinlog cannot read binlog event generated by user variable usage
Submitted:	21 Nov 2007 16:31	Modified:	6 Feb 2008 16:01
Reporter:	Guilhem Bichot	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Replication	Severity:	S1 (Critical)
Version:	5.1-bk	OS:	Linux
Assigned to:	Mats Kindahl	CPU Architecture:	Any

Description:
In statement-based or mixed binlogging mode, when a user variable (@something) is used inside an INSERT statement, a User_var binlog event is written to the binlog, and is needed for the statement to replay properly.
Apparently in 5.1 this is broken:
on one installation I see mysqlbinlog print
SET @`r`:=%.14/*!*/;
which is not valid syntax, and on another installation mysqlbinlog segfaults.
This is S1 because it endangers recovery from backups, and so could even be P1 if I had this power :)

How to repeat:
create t/bug.test:
-- source include/have_binlog_format_mixed_or_statement.inc
create table u(a int);
set @r=(rand()*1000-500);
insert into u values(@r);
select * from u;
show binlog events;

run that in 5.1 (./mtr --record bug): the result file will be correct, but mysqlbinlog on this binlog will show incorrect results or crash.

verified with latest 5.1-rpl, by Sven

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/38247

ChangeSet@1.2619, 2007-11-21 22:23:33+01:00, mats@kindahl-laptop.dnsalias.net +3 -0
  BUG#32580 (mysqlbinlog cannot read binlog event generated by user variable usage):
  
  The client program 'mysqlbinlog' crashed when trying to print a User_var_log_event holding
  a floating-point value since the format specifier for my_b_printf() does not support
  floating-point format specifiers.
  
  This patch prints the floating-point number to an internal buffer, and then writes
  that buffer to the output instead.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/38348

ChangeSet@1.2619, 2007-11-23 12:26:20+01:00, mats@kindahl-laptop.dnsalias.net +3 -0
  BUG#32580 (mysqlbinlog cannot read binlog event generated by user variable usage):
  
  The client program 'mysqlbinlog' crashed when trying to print a User_var_log_event holding
  a floating-point value since the format specifier for my_b_printf() does not support
  floating-point format specifiers.
  
  This patch prints the floating-point number to an internal buffer, and then writes
  that buffer to the output instead.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/38370

ChangeSet@1.2619, 2007-11-23 14:41:41+01:00, mats@kindahl-laptop.dnsalias.net +3 -0
  BUG#32580 (mysqlbinlog cannot read binlog event generated by user variable usage):
  
  The client program 'mysqlbinlog' crashed when trying to print a User_var_log_event holding
  a floating-point value since the format specifier for my_b_printf() does not support
  floating-point format specifiers.
  
  This patch prints the floating-point number to an internal buffer, and then writes
  that buffer to the output instead.

Pushed into 5.1.24-rc

Pushed into 6.0.5-alpha

Documented in the 5.1.24 and 6.0.5 changelogs as follows:

        When a user variable was used inside an
        INSERT statement, the corresponding binlog
        event was not written to the binlog correctly.

Also documented for 5.1.23-ndb-6.2.14.

Also documented for 5.1.23-ndb-6.3.11.