This was caused by a combination of factors:
* MyISAM/Aria temporary tables historically never saved the state
to disk (MYI/MAI), because the state never needed to persist
* certain ALTER TABLE operations modify the original TABLE structure
and if they fail, the original table has to be reopened to
revert all changes (m_needs_reopen=1)
as a result, when ALTER fails and MyISAM/Aria temp table gets reopened,
it reads the stale state from the disk.
As a fix, MyISAM/Aria tables now *always* write the state to disk
on close, *unless* HA_EXTRA_PREPARE_FOR_DROP was done first. And
the server now always does HA_EXTRA_PREPARE_FOR_DROP before dropping
a temporary table.
.. share->last_version' failed in myisam/mi_open.c:67: test_if_reopen
During the RENAME operation since the renamed temporary table is also
opened and added to myisam_open_list/maria_open_list, resetting the
last_version at the end of operation (HA_EXTRA_PREPARE_FOR_RENAME)
will cause an assertion failure when a subsequent query tries to open
an additional temporary table instance and thus attempts to reuse it
from the open table list.
This commit fixes the issue by skipping flush/close operations executed
toward the end of ALTER for temporary tables. It also enables a shortcut
for simple ALTERs (like rename, disable/enable keys) on temporary
tables.
As safety checks, added some assertions at code points that should not
be hit for temporary tables.
Since a query can now refer to the same temporary table
multiple times, find_dup_table()/find_table_in_list()
have been updated to also consider this new possibility.
Temporary table being created by outer statement
should not be visible to inner statement. And if
inner statement creates a table with same name.
The whole statement should fail with
ER_TABLE_EXISTS_ERROR.
Implemented by temporarily de-linking the TABLE_SHARE
being created by outer statement so that it remains
hidden to the inner statement.
mysqld maintains a list of TABLE objects for all temporary
tables created within a session in THD. Here each table is
represented by a TABLE object.
A query referencing a particular temporary table for more
than once, however, failed with ER_CANT_REOPEN_TABLE error
because a TABLE_SHARE was allocate together with the TABLE,
so temporary tables always had only one TABLE per TABLE_SHARE.
This patch lift this restriction by separating TABLE and
TABLE_SHARE objects and storing TABLE_SHAREs for temporary
tables in a list in THD, and TABLEs in a list within their
respective TABLE_SHAREs.
