execute crashes server": we were deleting lex->result
after each execute, but prepared statements assumed that
it's left intact.
The fix adds cleanup() method to select_result hierarchy,
so that result objects can be reused.
Plus we now need to delete result objects more wisely.
* When executing EXPLAIN, do the same as for the query: convert join type to JT_CONST if keyuse array covers all key parts and all of them are constants.
* In remove_const, don't remove conditions that depend on some-const-table and current-table.
We have next problem here:
active_index is wrong in the subselect's handler on the second val_int() call.
Optimizer sees that we can use index-read for that kind of condition,
and matching_cond() (sql/opt_sum.cc) doesn't. I suspect, proper solution is
to add appropriate code to the matching_cond() but now just added
missed initialization.
Added test case for bug #4256.
join_outer.result:
Fixed bug #4256.
item_cmpfunc.h:
Fixed inconsistency of values of used_tables_cache and
const_item_cache for Item_func_isnull objects.
This inconsistency caused bug #4256.
a second time". The bug was caused by incompatibility of
negations elimination algorithm and PS: during first statement
execute a subtree with negation was replaced with equivalent
subtree without NOTs.
The problem was that although this transformation was permanent,
items of the new subtree were created in execute-local memory.
The patch adds means to check if it is the first execute of a
prepared statement, and if this is the case, to allocate items
in memory of the prepared statement.
The implementation:
- backports Item_arena from 5.0
- adds Item_arena::is_stmt_prepare(),
Item_arena::is_first_stmt_execute().
- deletes THD::allocate_temporary_pool_for_ps_preparing(),
THD::free_temporary_pool_for_ps_preparing(); they
were redundant.
and adds a few invariants:
- thd->free_list never contains junk (= freed items)
- thd->current_arena is never null. If there is no
prepared statement, it points at the thd.
The rest of the patch contains mainly mechanical changes and
cleanups.
in a deadlock-free manner. This splits locking the global read lock in two steps.
This fixes a consequence of this bug, known as:
BUG#4953 'mysqldump --master-data may report incorrect binlog position if using InnoDB'
And a test.
