Introduce User_table_tabular(mysql.user) and User_table_json(mysql.global_priv).
The latter is not implemented.
Automatic fallback to the old implementation works.
Results change because privilege tables are opened in a different
order now.
When update finishes, MDL_context::release_transactional_locks() first
releases MDL_STATEMENT locks (MDL_BACKUP_DML and MDL_BACKUP_TRANS_DML
in this particular cases), which allows FTWRL connection to proceed.
Then MDL_TRANSACTION locks get released (MDL_SHARED_WRITE in this case).
metadata_lock_info query may sporadically hit this gap and observe
these otherwise unexpected locks.
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.
Alter statement changed the THD structure by setting the value to FIELD_CHECK_WARN
and then not resetting it back. This led ANALYZE to throw a warning which previously
it didn't.
MDEV-17772 - 3 way lock : ALTER, MDL, BACKUP STAGE BLOCK_DDL
While waiting for a (potentially long) RO transaction or SELECT, DDL and
LOCK TABLES ... WRITE hold protection against FTWRL and BACKUP STAGE.
This effectively makes FTWRL/BACKUP STAGE indirectly wait for this RO
transaction or SELECT to finish. Which is not great, as otherwise we
could do something useful meanwhile.
With this patch BACKUP lock is attempted to be acquired after TABLE/SCHEMA
locks. If this attempt fails, TABLE/SCHEMA locks gets released and we
start waiting for BACKUP lock. When wait finishes, BACKUP lock is released
(to avoid deadlocks) and we attempt to acquire all locks once again.
Other changes:
- Take MDL lock before testing if table exists as part of
CREATE TABLE ... IF EXISTS. This change was an effect of changes in
lock_table_name and removes an inconsistency where one could get
different error messages from CREATE TABLE .. IF EXISTS depending on
active mdl locks.
One effect of this change is that we don't binary log CREATE TABLE IF
EXISTS if the table exists. This was done because old code was sometimes
behaving inconsistenly (it was logged some time and not other times)
and sending the query to the slave could make the slave even more
inconsistent as there is not guarantee that the new table will have
the same definition as the old table on the master.
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.
Part of MDEV-5336 Implement LOCK FOR BACKUP
FLUSH TABLE table_names have changed slighty as we are now opening
tables before taking the MDL lock. The difference is that FLUSH TABLE
table_name will now be blocked by a table that is waiting for FTWRL.
There should not be any new deadlocks as part of this change.
The end result is still better in most cases as FTWRL is now only
waiting for write statements to end, not for read only statements and
it's not flushing tables in use from the table cache.
Share will be needed to be able to determine if table supports online
backup. Appropriate metadata lock type in BACKUP namespace will be
acquired basing on this information.
Also made pending global read lock request to be preferred victim of MDL
deadlock detector. This allows us to hide some non-fatal deadlocks and
make FTWRL less likely to break concurrent queries.
Part of MDEV-5336 Implement LOCK FOR BACKUP
Originally both table metadata lock and global read lock protection
were acquired before getting TABLE from table cache. This will be
reordered in a future commit with MDL_BACKUP_XXX locks so that we
first take table metadata lock, then get TABLE from table cache, then
acquire analogue of global read lock.
This patch both simplifies FLUSH TABLES code, makes FLUSH TABLES to
lock less and also enables FLUSH TABLES code to be used with backup
locks.
The usage of FLUSH TABLES changes slightly:
- FLUSH TABLES without any arguments will now only close not used tables
and tables locked by the FLUSH TABLES connection. All not used table
shares will be closed.
Tables locked by the FLUSH TABLES connection will be reopened and
re-locked after all others has stoped using the table (as before).
If there was no locked tables, then FLUSH TABLES is instant and will
not cause any waits.
FLUSH TABLES will not wait for any in use table.
- FLUSH TABLES with a table list, will ensure that the tables are closed
before statement returns. The code is now only using MDL locks and not
table share versions, which simplices the code greatly. One visible
change is that the server will wait for the end of the transaction that
are using the tables. Before FLUSH TABLES only waited for the statements
to end.
Signed-off-by: Monty <monty@mariadb.org>
Part of MDEV-5336 Implement LOCK FOR BACKUP
The idea is that instead of waiting in close_cached_tables() for all
tables to be closed, we instead call flush_tables() that does:
- Flush not used objects in table cache to free memory
- Collect all tables that are open
- Call HA_EXTRA_FLUSH on the objects, to get them into "closed state"
- Added HA_EXTRA_FLUSH support to archive and CSV
- Added multi-user protection to HA_EXTRA_FLUSH in MyISAM and Aria
The benefit compared to old code is:
- FTWRL doesn't have to wait for long running read operations or
open HANDLER's
- Moved tests depending on utf8 characters from create to create_utf8
- Fixed some tests in create and sp that wrongly tried to create table
from non existing table on existing table. In a later patch we may
first check if table exists, in which case the error message would
change.
- Updated results for partition_debug_tokudb
Added to new values to the server variable use_stat_tables.
The values are COMPLEMENTARY_FOR_QUERIES and PREFERABLY_FOR_QUERIES.
Both these values don't allow to collect EITS for queries like
analyze table t1;
To collect EITS we would need to use the syntax with persistent like
analyze table t1 persistent for columns (col1,col2...) index (idx1, idx2...) / ALL
Changing the default value from NEVER to PREFERABLY_FOR_QUERIES.
Sort acl_users inside the mysql_rename_user()'s loop, after every
successful iteration.
This is needed because on the next loop's iteration find_user_exact()
is used, which requires correct sorting by name.
This patch changes how old rows in mysql.gtid_slave_pos* tables are deleted.
Instead of doing it as part of every replicated transaction in
record_gtid(), it is done periodically (every @@gtid_cleanup_batch_size
transaction) in the slave background thread.
This removes the deletion step from the replication process in SQL or worker
threads, which could speed up replication with many small transactions. It
also decreases contention on the global mutex LOCK_slave_state. And it
simplifies the logic, eg. when a replicated transaction fails after having
deleted old rows.
With this patch, the deletion of old GTID rows happens asynchroneously and
slightly non-deterministic. Thus the number of old rows in
mysql.gtid_slave_pos can temporarily exceed @@gtid_cleanup_batch_size. But
all old rows will be deleted eventually after sufficiently many new GTIDs
have been replicated.
sorting them by usernames first, and then by get_sort() value.
Search functions now use binary search to find the the first entry with
given name. Then, linear search is done, until the first match.
Added support for usual agreggate UDF (UDAF)
Added remove() call support for more efficient window function processing
Added example of aggregate UDF with efficient windows function support
