In Galera case we call check_engine that could set create_info->db_type
to NULL e.g. if TEMPORARY is not supported by storage engine. Thus,
we need to restore it after that call because it is needed later
on mysql_create_table that will also call check_engine.
MDEV-25856 : SIGSEGV in ha_myisammrg::append_create_info
For MERGE-tables we need to init children list before calling
show_create_table and then detach children before we continue
normal mysql_create_like_table execution.
MDEV-25472 : Server crashes when wsrep_cluster_address set to unkown address and wsrep_slave_threads to 0
Return failure if we are not connected when slave threads are set
89c870b...
by
Dmitry Shulga <email address hidden>
MDEV-20325: Assertion `outer_context || !*from_field || *from_field == not_found_field' failed in Item_field::fix_outer_field | `!derived->is_excluded()' failed in TABLE_LIST::set_check_materialized | SIGEGV in st_select_lex::mark_as_dependent (optimized builds)
Re-execution of a query containing subquery in the FROM clause results
in assert failure in case the query is run as part of a stored routine or
as a prepared statement AND derived table merge optimization is off.
As an example, the following test case
CREATE TABLE t1 (a INT) ;
CREATE PROCEDURE sp() SELECT * FROM (SELECT a FROM t1) tb;
CALL sp();
SET optimizer_switch='derived_merge=off';
CALL sp();
results in assert failure on the second invocation of the 'sp' stored routine.
The reason for assertion failure is that the expression
derived->is_excluded()
returns the value true where the value false expected.
The method is_excluded() returns the value true for a derived table
that has been merged to a parent select. Such transformation happens as part
of Derived Table Merge Optimization that is performed on first invocation of
a stored routine or a prepared statement containing a query with subquery
in the FROM clause of the main SELECT.
When the same routine or prepared statement is run the second time and
Derived Table Merge Optimization is OFF the MariaDB server tries to materialize
a derived table specified by the subquery that fails since this subquery
has already been merged to the top-most SELECT. This transformation is permanent
and can't be reverted. That is the reason why the assert
DBUG_ASSERT(!derived->is_excluded());
fails inside the function TABLE_LIST::set_check_materialized().
Similar behaviour can be observed in case a stored routine or prepared statement
containing a SELECT statement with subquery in the FROM clause, first is run
with the optimizer_switch option set to derived_merge=off and re-run after this
option has been switched to derived_merge=on. In this case a derived table for
subquery is materialized on the first execution and marked as merged derived
table on the second execution that results in error with misleading error
message:
MariaDB [test]> CALL sp1();
ERROR 1030 (HY000): Got error 1 "Operation not permitted" from storage engine MEMORY
To fix the issue, a derived table that has been already optimized shouldn't be
re-marked for one more round of optimization.
One significant consequence following from suggested change is that the data
member TABLE_LIST::derived_type is not updated once the table optimization
has been done. This fact should be taken into account when Prepared Statement
being handled since once a table listed in a query has been optimized on
execution of the statement PREPARE FROM it won't be touched anymore on handling
the statement EXECUTE.
One side effect caused by this change could be observed for the following
test case:
CREATE TABLE t1 (s1 INT);
CREATE VIEW v1 AS
SELECT s1,s2 FROM (SELECT s1 as s2 FROM t1 WHERE s1 <100) x, t1 WHERE t1.s1=x.s2;
INSERT INTO v1 (s1) VALUES (-300);
PREPARE stmt FROM "INSERT INTO v1 (s1) VALUES (-300)";
EXECUTE stmt;
Execution of the above EXECUTE statement results in issuing the error
ER_COLUMNACCESS_DENIED_ERROR since table_ref->is_merged_derived() is false
and check_column_grant_in_table_ref() called for a temporary table that
shouldn't be. To fix this issue the function find_field_in_tables has been
modified in such a way that the function check_column_grant_in_table_ref()
is not called for a temporary table.
MDEV-25631 Crash executing query with VIEW, aggregate and subquery
This bug could cause a crash of the server for queries with a derived table
whose specification contained the set function using a subquery over a view
as its only argument. The crash could happen if the specification of the
view contained an outer reference. In this case the aggregation select
could be determined incorrectly.
The crash also could be observed if a CTE is used instead of the view, but
only for queries having at least two references to the CTE.
The cause of this bug is the same as of the bug MDEV-24454.
This bug manifested itself at the second execution of the queries that
contained a set function whose only argument was outer reference to
a column of a mergeable view or derived table or CTE. The first execution
of such query worked fine, but the second execution of the query caused
a crash of the server because the aggregation select for the used set
function was determined incorrectly at the name resolution phase of the
second execution.
This patch reverts the fixes of the bugs MDEV-24454 and MDEV-25631 from
the commit 3690c549c6e72646ba74f6b4c83813ee4ac3aea4.
It leaves the changes in plugin/feedback/feedback.cc and corresponding
test files introduced in this commit intact.
Proper fixes for the bug MDEV-24454 and MDEV-25631 will follow immediately.
