read_statistics_for_tables_if_needed
Regression after 279a907, read_statistics_for_tables_if_needed() was
called after open_normal_and_derived_tables() failure.
Fixed by moving read_statistics_for_tables() call to a branch of
get_schema_stat_record() where result of open_normal_and_derived_tables()
is checked.
Removed THD::force_read_stats, added read_statistics_for_tables() instead.
Simplified away statistics_for_command_is_needed().
- call current_schema::mark_as_changed() directly
- call state_change::mark_as_changed() directly
- replaced SESSION_TRACKER_CHANGED with dummy tracker
- replaced Session_tracker::mark_as_changed() with
State_tracker::mark_as_changed()
- hide and devirtualize original State_tracker::mark_as_changed(),
rename it to set_changed()
- all implementations of mark_as_changed() now check is_enabled() for
consistency
- no argument casts anymore
MDEV-17614 flags INSERT…ON DUPLICATE KEY UPDATE unsafe for statement-based
replication when there are multiple unique indexes. This correctly fixes
something whose attempted fix in MySQL 5.7
in mysql/mysql-server@c93b0d9a97
caused lock conflicts. That change was reverted in MySQL 5.7.26
in mysql/mysql-server@066b6fdd43
(with a substantial amount of other changes).
In MDEV-17073 we already disabled the unfortunate MySQL change when
statement-based replication was not being used. Now, thanks to MDEV-17614,
we can actually remove the change altogether.
This reverts commit 8a346f31b9 (MDEV-17073)
and mysql/mysql-server@c93b0d9a97 while
keeping the test cases.
Problem:-
When mysql executes INSERT ON DUPLICATE KEY INSERT, the storage engine checks
if the inserted row would generate a duplicate key error. If yes, it returns
the existing row to mysql, mysql updates it and sends it back to the storage
engine.When the table has more than one unique or primary key, this statement
is sensitive to the order in which the storage engines checks the keys.
Depending on this order, the storage engine may determine different rows
to mysql, and hence mysql can update different rows.The order that the
storage engine checks keys is not deterministic. For example, InnoDB checks
keys in an order that depends on the order in which indexes were added to
the table. The first added index is checked first. So if master and slave
have added indexes in different orders, then slave may go out of sync.
Solution:-
Make INSERT...ON DUPLICATE KEY UPDATE unsafe while using stmt or mixed format
When there is more then one unique key.
Although there is two exception.
1. Auto Increment key is not counted because Innodb will get gap lock for
failed Insert and concurrent insert will get a next increment value. But if
user supplies auto inc value it can be unsafe.
2. Count only unique keys for which insertion is performed.
So this patch also addresses the bug id #72921
Sources did not compile in some builds because of undeclared
ER_BLOB_KEY_WITHOUT_LENGTH. Moving the implementations of
Key_part_spec::check_key_length_for_blob() from sql_class.h to sql_class.cc
Plugin fixed to not lock the LOCK_operations when not active.
Server fixed to lock the LOCK_plugin less - do it once per
thread and then only if a plugin was installed/uninstalled.
Originally introduced by e972125f1 to avoid harmless wait for
LOCK_global_system_variables in a newly created thread, which creation was
initiated by system variable update.
At the same time it opens dangerous hole, when system variable update
thread already released LOCK_global_system_variables and ack_receiver
thread haven't yet completed new THD construction. In this case THD
constructor goes completely unprotected.
Since ack_receiver.stop() waits for the thread to go down, we have to
temporarily release LOCK_global_system_variables so that it doesn't
deadlock with ack_receiver.run(). Unfortunately it breaks atomicity
of rpl_semi_sync_master_enabled updates and makes them not serialized.
LOCK_rpl_semi_sync_master_enabled was introduced to workaround the above.
TODO: move ack_receiver start/stop into repl_semisync_master
enable_master/disable_master under LOCK_binlog protection?
Part of MDEV-14984 - regression in connect performance
Rather than parsing session_track_system_variables when thread starts, do
it when first trackable event occurs.
Benchmarked on a 2socket/20core/40threads Broadwell system using sysbench
connect brencmark @40 threads (with select 1 disabled):
101379.77 -> 143016.68 CPS, whereas 10.2 is currently at 137766.31 CPS.
Part of MDEV-14984 - regression in connect performance
One less new/delete per connection.
Removed m_mem_flag since most allocs are thread specific. The only
exception are allocs performed during initialization.
Removed State_tracker and Session_tracker constructors as they don't make
sense anymore.
No reason to access session_sysvars_tracker via get_tracker(), so access
it directly instead.
Part of MDEV-14984 - regression in connect performance
If a derived table has SELECT DISTINCT, provide index statistics for it so that the join optimizer in the
upper select knows that ref access to the table will produce one row.
depends on uninitialised value
Initialized THD::force_read_stats introduced in the patch for MDEV-17605.
Leaving this field uninitialized in the constructor of the THD class may
trigger reading statistical data that is not needed.
depends on uninitialised value
Initialized THD::force_read_stats introduced in the patch for MDEV-17605.
Leaving this field uninitialized in the constructor of the THD class may
trigger reading statistical data that is not needed.
Let xid_cache_insert()/xid_cache_delete() handle xa_state.
Let session tracker use is_explicit_XA() rather than xa_state != XA_NOTR.
Fixed open_tables() to refuse data access in XA_ROLLBACK_ONLY state.
Removed dead code from THD::cleanup(). It was supposed to be a reminder,
but it got messed up over time.
spider_internal_start_trx() is called either with XA_NOTR or XA_ACTIVE,
which is guarded by server callers. Thus is_explicit_XA() is acceptable
replacement for XA_ACTIVE check (which was likely wrong anyway).
Setting xa_state to XA_PREPARED in spider_internal_xa_prepare() isn't
meaningful, as this value is never accessed later. It can't be accessed
by current thread and it can't be recovered either. It can only be
accessed by spider internally, which never happens.
Make spider_xa_lock()/spider_xa_unlock() static.
Part of MDEV-7974 - backport fix for mysql bug#12161 (XA and binlog)
XID_STATE::rm_error is never used by internal 2PC, it is intended to be
used by explicit XA only.
Also removed redundant xid reset from THD::init_for_queries(). Must've
been done already either by THD::transaction constructor or by
THD::cleanup().
Part of MDEV-7974 - backport fix for mysql bug#12161 (XA and binlog)
