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From:Libing Song Date:September 20 2010 7:16am
Subject:Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)
Bug#56226
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On Mon, 2010-09-20 at 10:53 +0400, Dmitry Lenev wrote:
> Hello Li-Bing!
> 
> Here are my comment about your patch:
> 
> * Li-Bing.Song@stripped <Li-Bing.Song@stripped> [10/09/16 13:40]:
> > #At file:///home/anders/work/bzrwork1/wt2/mysql-5.1-bugteam/ based on
> revid:mattias.jonsson@stripped
> > 
> >  3489 Li-Bing.Song@stripped	2010-09-16
> >       Bug#56226  Table map set to 0 after altering MyISAM table
> >       
> >       A MyISAM table's table_map_id will always be reset to 0 after altered
> >       only its metadata. 0 is a valid value of table_map_id. But the problem
> will
> >       cause that more than one tables have the same table_map_id 0. If more
> than
> >       one tables which's table_map_id are 0 are updated in one statement, the
> update
> >       of these different tables will be write into only one rows event. It will
> >       cause slave server to crash. 
> >       
> >       After this patch, table_map_id always be refreshed as a correct value
> after
> >       altered only its metadata.
> 
> ...
> 
> > === modified file 'sql/sql_base.cc'
> > --- a/sql/sql_base.cc	2010-07-20 18:07:36 +0000
> > +++ b/sql/sql_base.cc	2010-09-16 09:35:41 +0000
> > @@ -662,6 +662,7 @@ void close_handle_and_leave_table_as_loc
> >      share->set_table_cache_key(key_buff, old_share->table_cache_key.str,
> >                                 old_share->table_cache_key.length);
> >      share->tmp_table= INTERNAL_TMP_TABLE;       // for intern_close_table()
> > +    share->table_map_id= ~0UL;
> >    }
> >  
> >    /*
> > @@ -3082,7 +3083,8 @@ bool reopen_table(TABLE *table)
> >    tmp.maybe_null=	table->maybe_null;
> >    tmp.status=		table->status;
> >  
> > -  tmp.s->table_map_id=  table->s->table_map_id;
> > +  if (table->s->table_map_id != ~0UL)
> > +    tmp.s->table_map_id=  table->s->table_map_id;
> >  
> 
> I don't think that there is a situation when it makes sense to
> inherit table_map_id from old version of share here.
> Especially since, AFAIU, shares for TABLE objects for which 
> reopen_table() is called are always dummy and not a real shares.
I agree with you. I just have a little bit worry that if it will effect
other code. As reopen_table is also called in other place.
> 
> So I think it makes sense simply to remove this line and keep 
> close_handle_and_leave_table_as_lock() as is.
It doesn't make sense to initialize table_map_id as 0. It is not
reasonable. If table_map_id has been initialized as ~0UL, we would have
found this bug no soon after the code was committed.
> 

-- 
Your Sincerely,
Libing Song
==================================
MySQL Replication Team
Software Engineer


Email : Li-Bing.Song@stripped
Skype : libing.song
MSN   : slb_database@stripped
Phone : +86 010-6505-4020 ext. 319
Mobile: +86 138-1144-2038
==================================

Thread
bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489) Bug#56226Li-Bing.Song16 Sep
  • Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)Bug#56226He Zhenxing17 Sep
  • Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)Bug#56226Dmitry Lenev20 Sep
Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)Bug#56226Libing Song20 Sep
  • Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)Bug#56226Dmitry Lenev20 Sep
    • Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)Bug#56226Libing Song20 Sep
Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)Bug#56226Dmitry Lenev20 Sep
  • Re: bzr commit into mysql-5.1-bugteam branch (Li-Bing.Song:3489)Bug#56226He Zhenxing20 Sep