MySQL Bugs: #28414: please add more useful information to error logs when corruption occurs

Bug #28414	please add more useful information to error logs when corruption occurs
Submitted:	14 May 2007 12:40	Modified:	23 Oct 2007 11:09
Reporter:	Shane Bester (Platinum Quality Contributor)	Email Updates:
Status:	Duplicate	Impact on me:	None
Category:	MySQL Server: MyISAM storage engine	Severity:	S4 (Feature request)
Version:	5.0.x, 5.1.x	OS:	Any
Assigned to:	Assigned Account	CPU Architecture:	Any
Tags:	bfsm_2007_05_31, bfsm_2007_06_21, bfsm_2007_06_28, corruption, myisam

Description:
When a myisam table becomes corrupted, mysql usually writes something like this to error log:

070514  9:43:48 [ERROR] mysqld-debug: Incorrect key file for table '.\test\t1.MYI'; try to repair it

However, this is not enough information.  
We require more useful errors, because these corruptions are
often a result of a mysql bug.

Some errors where we need the information are:
error 134, 127, 124, 126

How to repeat:
view error log and try determine a cause of table corruption.

Suggested fix:
The developers should add more information that can help them locate a cause of corruption.

Some ideas from me that could appear in error logs:

1) current running query which caused/found the corruption
2) current threads reading/writing from that table can be printed
3) the function/source code file in which the error originate can be printed.
4) dump the current processlist?
5) ... other ideas?

We need these to be included in the release version of mysql.

Thank you for a problem report.

See example of bug #27510 where more information is needed.

bug #28154 and #27510 classic examples of why we need better errors in the logs.

A good start could be to convert some DBUG_PRINT messages to fprintf so that would show up in a error log?

<cut>
 my_errno= HA_ERR_WRONG_IN_RECORD;
  DBUG_PRINT("error",("to_end: 0x%lx -> 0x%lx  from_end: 0x%lx -> 0x%lx",
		      (long) to, (long) to_end, (long) from, (long) from_end));
  DBUG_DUMP("from",(byte*) info->rec_buff,info->s->base.min_pack_length);
  DBUG_RETURN(MY_FILE_ERROR);

..

 DBUG_PRINT("error",("Delete link crashed"));

..

DBUG_PRINT("error",("Got wrong block info"));

..

DBUG_PRINT("error",("to_end: 0x%lx -> 0x%lx  from_end: 0x%lx -> 0x%lx",
		      (long) to, (long) to_end, (long) from, (long) from_end));
..

etc,

if an innodb corruption occurs in innodb, we can normally make a good diagnosis from the error log and assertions of a probable cause.

not so with myisam!  we need that greater level of diagnostics.  even innodb still has bugs with corruption today, but the reason we found them was due to assertions....

A duplicate of WL#3951.