Implemented and integrated THD_list as a replacement for the global
thread list. It uses own mutex instead of LOCK_thread_count for THD
list protection.
Removed unused first_global_thread() and next_global_thread().
delayed_insert_threads is now protected by LOCK_delayed_insert. Although
this patch doesn't fix very wrong synchronization of this variable.
After this patch there are only 2 legitimate uses of LOCK_thread_count
left, both in mysqld.cc: thread_count and ready_to_exit.
Aim is to reduce usage of LOCK_thread_count and COND_thread_count.
Part of MDEV-15135.
After MDEV-17772 table existence check is performed much earlier, so
create_table_select_before_check_if_exists debug sync point is not
reachable when table exists.
Moved debug sync point to appropriate place.
Part of MDEV-5336 Implement LOCK FOR BACKUP
- Changed check of Global_only_lock to also include BACKUP lock.
- We store latest MDL_BACKUP_DDL lock in thd->mdl_backup_ticket to be able
to downgrade lock during copy_data_between_tables()
Part of MDEV-5336 Implement LOCK FOR BACKUP
- Added new locks to MDL_BACKUP for all stages of backup locks and
a new MDL lock needed for backup stages.
- Renamed MDL_BACKUP_STMT to MDL_BACKUP_DDL
- flush_tables() takes a new parameter that decides what should be flushed.
- InnoDB, Aria (transactional tables with checksums), Blackhole, Federated
and Federatedx tables are marked to be safe for online backup. We are
using MDL_BACKUP_TRANS_DML instead of MDL_BACKUP_DML locks for these
which allows any DML's to proceed for these tables during the whole
backup process until BACKUP STAGE COMMIT which will block the final
commit.
FLUSH TABLES kills all insert delayed treads. If this happens at same time
as a newly started insert delayed query, the insert may fail with either
and error ("Query interrupted") or the row may be lost.
This patch fixes this by changing a failed attempt of get_delay_table() to
convert the query to use a normal insert.
The test case for this patch can be found in the FLUSH TABLES commit after
this one.
main.derived_cond_pushdown: Move all 10.3 tests to the end,
trim trailing white space, and add an "End of 10.3 tests" marker.
Add --sorted_result to tests where the ordering is not deterministic.
main.win_percentile: Add --sorted_result to tests where the
ordering is no longer deterministic.
The problem described in the bug report happened because the code
did not test check_cols(1) after fix_fields() in a few places.
Additionally, fix_fields() could be called multiple times for SP variables,
because they are all fixed at a early stage in append_for_log().
Solution:
1. Adding a few helper methods
- fix_fields_if_needed()
- fix_fields_if_needed_for_scalar()
- fix_fields_if_needed_for_bool()
- fix_fields_if_needed_for_order_by()
and using it in many cases instead of fix_fields() where
the "fixed" status is not definitely known to be "false".
2. Adding DBUG_ASSERT(!fixed) into Item_splocal*::fix_fields()
to catch double execution.
3. Adding tests.
As a good side effect, the patch removes a lot of duplicate code (~60 lines):
if (!item->fixed &&
item->fix_fields(..) &&
item->check_cols(1))
return true;
Detailed: changes:
1. Moving Field specific code into new methods on Field:
- Field *Field::create_tmp_field(...)
- virtual void init_for_tmp_table(...)
2. Removing virtual Item::create_tmp_field().
Adding instead a new virtual method Item::create_tmp_field_ex().
Note, a virtual create_tmp_field() still exists, but only for Item_sum.
This resembles 10.0 code structure. Perhaps create_tmp_field() should
be removed from Item_sum and Item_sum descendants should override
create_tmp_field_ex() directly. This can be done in a separate commit.
3. Adding helper classes Tmp_field_src and Tmp_field_param,
to make the API for Item::create_tmp_field_ex() smaller
and easier to extend in the future.
4. Decomposing the public function create_tmp_field() into
virtual implementations for Item and a number of its descendants:
- Item_basic_value
- Item_sp_variable
- Item_name_const
- Item_result_field
- Item_field
- Item_ref
- Item_type_holder
- Item_row
- Item_func_sp
- Item_func_user_var
- Item_sum
- Item_sum_field
- Item_proc
5. Adding DBUG_ASSERT-only virtual implementations for
Item types that should not appear in create_tmp_table_ex(),
for easier debugging:
- Item_nodeset_func
- Item_nodeset_to_const_comparator
- Item_null_result
- Item_copy
- Item_ident_for_show
- Item_user_var_as_out_param
6. Moving public function create_tmp_field_from_field()
as a method to Item_field.
7. Removing Item::set_result_field(). It's not needed any more.
8. Cleanup: Removing the enum value "EXPR_CACHE_ITEM",
as it's not used for a very long time.
preserve positions if the multi-update join is using tmp table:
* store positions in the tmp table if needed
JOIN::add_fields_for_current_rowid()
* take positions from the tmp table, not from file->position():
multi_update::prepare2()
Fixed by extending unique_table() with a flag to not allow usage of
the replaced table.
I also cleaned up find_dup_table() to not use goto next.
I also added more comments to the code in find_dup_table()
These test can sporadically show mutex deadlock warnings between LOCK_wsrep_thd
and LOCK_thd_data mutexes. This means that these mutexes can be locked in opposite
order by different threads, and thus result in deadlock situation.
To fix such issue, the locking policy of these mutexes should be revised and
enforced to be uniform. However, a quick code review shows that the number of
lock/unlock operations for these mutexes combined is between 100-200, and all these
mutex invocations should be checked/fixed.
On the other hand, it turns out that LOCK_wsrep_thd is used for protecting access to
wsrep variables of THD (wsrep_conflict_state, wsrep_query_state), whereas LOCK_thd_data
protects query, db and mysys_var variables in THD. Extending LOCK_thd_data to protect
also wsrep variables looks like a viable solution, as there should not be a use case
where separate threads need simultaneous access to wsrep variables and THD data variables.
In this commit LOCK_wsrep_thd mutex is refactored to be replaced by LOCK_thd_data.
By bluntly replacing LOCK_wsrep_thd by LOCK_thd_data, will result in double locking
of LOCK_thd_data, and some adjustements have been performed to fix such situations.
Modern compilers (such as GCC 8) emit warnings that the
'register' keyword is deprecated and not valid C++17.
Let us remove most use of the 'register' keyword.
Code in 'extra/' is not touched.
numerous fixes for CREATE ... SELECT with system versioning:
In CREATE ... SELECT the table is created based on the result set,
field properties do not count. That is
* field invisibility is *not* copied over
* AS ROW START/END is *not* copied over
* the history is *not* copied over
* system row_start/row_end fields can *not* be created from the SELECT part
enum_mark_columns -> enum_column_usage
mark_used_columns -> column_usage
further commits will replace MARK_COLUMN_NONE with
COLUMN_READ and COLUMN_WRITE that convey the intention
without causing columns to be marked
