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
> 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,
> 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.
So I think it makes sense simply to remove this line and keep
close_handle_and_leave_table_as_lock() as is.
Dmitry Lenev, Software Developer
Oracle Development SPB/MySQL, www.mysql.com
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