InnoDB does not attempt to handle lower_case_table_names == 2 when looking
up foreign table names and referenced table name. It turned that server
variable into a boolean and ignored the possibility of it being '2'.
The setting lower_case_table_names == 2 means that it should be stored and
displayed in mixed case as given, but compared internally in lower case.
Normally the server deals with this since it stores table names. But
InnoDB stores referential constraints for the server, so it needs to keep
track of both lower case and given names.
This solution creates two table name pointers for each foreign and referenced
table name. One to display the name, and one to look it up. Both pointers
point to the same allocated string unless this setting is 2. So the overhead
added is not too much.
Two functions are created in dict0mem.c to populate the ..._lookup versions
of these pointers. Both dict_mem_foreign_table_name_lookup_set() and
dict_mem_referenced_table_name_lookup_set() are called 5 times each.
data dictionary confusion
On file systems with case insensitive file names, and
lower_case_table_names set to '2', the server could crash
due to a table definition cache inconsistency. This is
the default setting on MacOSX, but may also be set and
used on MS Windows.
The bug is caused by using two different strategies for
creating the hash key for the table definition cache, resulting
in failure to look up an entry which is present in the cache,
or failure to delete an existing entry. One strategy was to
use the real table name (with case preserved), and the other
to use a normalized table name (i.e a lower case version).
This is manifested in two cases. One is during 'DROP DATABASE',
where all known files are removed. The removal from
the table definition cache is done via a generated list of
TABLE_LIST with keys (wrongly) created using the case preserved
name. The other is during CREATE TABLE, where the cache lookup
is also (wrongly) based on the case preserved name.
The fix was to use only the normalized table name when
creating hash keys.
sql/sql_db.cc:
Normalize table name (i.e lower case it)
sql/sql_table.cc:
table_name contains the normalized name
alias contains the real table name
