When there are no underlying tables specified for a merge table,
SHOW CREATE TABLE outputs a statement that cannot be executed. The
same is true for mysqldump (it generates dumps that cannot be
executed).
This happens because SQL parser does not accept empty UNION() clause.
This patch changes the following:
- it is now possible to execute CREATE/ALTER statement with
empty UNION() clause.
- the same as above, but still worth noting: it is now possible to
remove underlying tables mapping using ALTER TABLE ... UNION=().
- SHOW CREATE TABLE does not output UNION() clause if there are
no underlying tables specified for a merge table. This makes
mysqldump slightly smaller.
m_status == DA_OK
Reading from information_scema.tables or information_schema.columns
may cause assertion failure in debug builds. This may happen under
rare circumstances when information_schema fails to get information
about a table (e.g. when a connection is killed).
This happens because open_normal_and_derived_tables() can return an
error without setting an error message in THD. But information_schema
attempts to get an error message from THD unconditionally.
With this fix information_schema attempts to get an error message
from THD only in case error message is set in THD.
- Apply Eric Bergen's patch: in join_read_always_key(), move ha_index_init() call
to before the late NULLs filtering code.
- Backport function comments from 6.0.
added new function test_if_data_home_dir() which checks that
path does not contain mysql data home directory.
Using of mysql data home directory in
DATA DIRECTORY & INDEX DIRECTORY is disallowed.
Assertion `0' failed
If ROW item is a part of an expression that also has
aggregate function calls (COUNT/SUM/AVG...), a
"splitting" with an Item::split_sum_func2 function
is applied to that ROW item.
Current implementation of Item::split_sum_func2
replaces this Item_row with a newly created
Item_aggregate_ref reference to it.
Then the row cache tries to work with the
Item_aggregate_ref object as with the Item_row object:
row cache calls row-emulation methods such as cols and
element_index. Item_aggregate_ref (like it's parent
Item_ref) inherits dummy implementations of those
methods from the hierarchy root Item, and call to
them leads to failed assertions and wrong data
output.
Row-emulation virtual functions (cols, element_index, addr,
check_cols, null_inside and bring_value) of Item_ref have
been overloaded to forward calls to an underlying item
reference.
The problem is that passing anything other than a integer to a limit
clause in a prepared statement would fail. This limitation was introduced
to avoid replication problems (e.g: replicating the statement with a
string argument would cause a parse failure in the slave).
The solution is to convert arguments to the limit clause to a integer
value and use this converted value when persisting the query to the log.
