Hi, Timothy!
Thanks.
I've submitted it as http://bugs.mysql.com/49329
Note that
1. there is a user visible incorrect behavior, so it's clearly a bug.
2. my_charset_bin is probably also incorrect, it'll result in a wrong
behavior when lower_case_table_names is enabled, table_alias_charset
is the one to use.
3. the recommended solution is to remove the hash completely and use
TABLE_SHARE::ha_data - it was added in 5.1 precisely for this
purpose, so that engines wouldn't need to maintain the mapping from
table names to shares, MySQL already does it anyway, the engine can
simply use it - remove the hash, the mutex to guard it, and simply
store the pointer in the TABLE_SHARE::ha_data, if possible.
On Dec 01, Timothy P Clark wrote:
> I've found what I believe to be a problem with the example storage engine.
> The problem also exists in the InnoDB and CSV storage engines. Strictly
> speaking, I can't call it a bug, since I don't think that any adverse
> behavior is generated for these cases. However, it does adversely affect
> our storage engine, which long ago used the example storage engine as its
> inspiration. Consequently, I would suggest that the example storage engine
> be fixed to prevent future storage engines from making a similar mistake.
>
> The problem is this: in the storage engine initialization function
> (example_init_func), the example_open_tables hash table is initialized to
> use the system_charset_info character set. This hash table is used to
> track information on a table-wide basis that is shared among handlers
> belonging to that table. However, because system_charset_info uses the
> utf8_general_ci collation, table names that differ only in letter case
> (e.g. ABC and abc) will hash to the same share. When our storage engine
> has two such tables open at the same time, odd behavior occurs because of
> this collision. I suspect that the appropriate solution is to use
> my_charset_bin instead of system_charset_info, as the federated engine
> does.
>
> Thank you,
> Tim Clark
>
>
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Regards / Mit vielen Grüßen,
Sergei
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