-----------------------------------------------------------
2630.28.28 Magne Mahre 2008-12-05
Bug #38661 'all threads hang in "opening tables" or "waiting for table"
and cpu is at 100%'
Concurrent execution of FLUSH TABLES statement and at least two statements
using the same table might have led to live-lock which caused all three
connections to stall and hog 100% of CPU.
tdc_wait_for_old_versions() wrongly assumed that there cannot be a share
with an old version and no used TABLE instances and thus was failing to
perform wait in situation when such old share was cached in MDL subsystem
thanks to a still active metadata lock on the table. So it might have
happened that two or more connections simultaneously executing statements
which involve table being flushed managed to prevent each other from
waiting in this function by keeping shared metadata lock on the table
constantly active (i.e. one of the statements managed to take/hold this
lock while other statements were calling tdc_wait_for_old_versions()).
Thus they were forcing each other to loop infinitely in open_tables() -
close_thread_tables_for_reopen() - tdc_wait_for_old_versions() cycle
causing CPU hogging.
This patch fixes this problem by removing this false assumption from
tdc_wait_for_old_versions().
Note that the problem is specific only for server versions >= 6.0.
No test case is submitted for this test, as the test infrastructure
hasn't got the necessary primitives to test the behaviour. The
manifestation is that throughput will decrease to a low level
(possibly 0) after some time, and stay at that level. Several
transactions will not complete.
Manual testing can be done by running the code submitted by Shane
Bester attached to the bug report. If the bug persists, the
transaction thruput will almost immediately drop to near zero
(shown as the transaction count output from the test program staying
on a close to constant value, instead of increasing rapidly).
(diagnostics_area)
Execution of CREATE TABLE ... SELECT statement was not atomic in
the sense that concurrent statements trying to affect its target
table might have sneaked in between the moment when the table was
created and moment when it was filled according to SELECT clause.
This resulted in inconsistent binary log, unexpected target table
contents. In cases when concurrent statement was a DDL statement
CREATE TABLE ... SELECT might have failed with ER_CANT_LOCK error.
In more detail:
Due to premature metadata lock downgrade which occured after CREATE
TABLE SELECT statement created table but before it managed to obtain
table-level lock on it other statements were allowed to open, lock
and change target table in the middle of CREATE TABLE SELECT
execution. This also meant that it was possible that CREATE TABLE
SELECT would wait in mysql_lock_tables() when it was called for newly
created table and that this wait could have been aborted by concurrent
DDL. The latter led to execution of unexpected branch of code and
CREATE TABLE SELECT ending with ER_CANT_LOCK error.
The premature downgrade occured because open_table(), which was called
for newly created table, decided that it is OK to downgrade metadata
lock from exclusive to shared since table exists, even although it
was not acquired within this call.
This fix ensures that open_table() does not downgrade metadata lock
if it is not acquired during its current invocation.
Testing:
The bug is exposed in a race condition, and is thus difficult to
expose in a standard mysql-test-run test case. Instead, a stress
test using the Random Query Generator (https://launchpad.net/randgen)
will trip the problem occasionally.
% perl runall.pl \
--basedir=<build dir> \
--mysqld=--table-lock-wait-timeout=5 \
--mysqld=--skip-safemalloc \
--grammar=conf/maria_bulk_insert.yy \
--reporters=ErrorLog,Backtrace,WinPackage \
--mysqld=--log-output=file \
--queries=100000 \
--threads=10 \
--engine=myisam
Note: You will need a debug build to expose the bug
When the bug is tripped, the server will abort and dump core.
Backport from 6.0-codebase (revid: 2617.53.4)
Bug #46654 False deadlock on concurrent DML/DDL with partitions,
inconsistent behavior
The problem was that if one connection is running a multi-statement
transaction which involves a single partitioned table, and another
connection attempts to alter the table, the first connection gets
ER_LOCK_DEADLOCK and cannot proceed anymore, even when the ALTER TABLE
statement in another connection has timed out or failed.
The reason for this was that the prepare phase for ALTER TABLE for
partitioned tables removed all instances of the table from the table
definition cache before it started waiting on the lock. The transaction
running in the first connection would notice this and report ER_LOCK_DEADLOCK.
This patch changes the prep_alter_part_table() ALTER TABLE code so that
tdc_remove_table() is no longer called. Instead, only the TABLE instance
changed by prep_alter_part_table() is marked as needing reopen.
The patch also removes an unnecessary call to tdc_remove_table() from
mysql_unpack_partition() as the changed TABLE object is destroyed by the
caller at a later point.
Test case added in partition_sync.test.
Bug#42546 Backup: RESTORE fails, thinking it finds an existing table
The problem occured when a MDL locking conflict happened for a non-existent
table between a CREATE and a INSERT statement. The code for CREATE
interpreted this lock conflict to mean that the table existed,
which meant that the statement failed when it should not have.
The problem could occur for CREATE TABLE, CREATE TABLE LIKE and
ALTER TABLE RENAME.
This patch fixes the problem for CREATE TABLE and CREATE TABLE LIKE.
It is based on code backported from the mysql-6.1-fk tree written
by Dmitry Lenev. CREATE now uses normal open_and_lock_tables() code
to acquire exclusive locks. This means that for the test case in the bug
description, CREATE will wait until INSERT completes so that it can
get the exclusive lock. This resolves the reported bug.
The patch also prohibits CREATE TABLE and CREATE TABLE LIKE under
LOCK TABLES. Note that this is an incompatible change and must
be reflected in the documentation. Affected test cases have been
updated.
mdl_sync.test contains tests for CREATE TABLE and CREATE TABLE LIKE.
Fixing the issue for ALTER TABLE RENAME is beyond the scope of this
patch. ALTER TABLE cannot be prohibited from working under LOCK TABLES
as this could seriously impact customers and a proper fix would require
a significant rewrite.
------------------------------------------------------------
revno: 2617.68.25
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg-pre2-2
timestamp: Wed 2009-09-16 18:26:50 +0400
message:
Follow-up for one of pre-requisite patches for fixing bug #30977
"Concurrent statement using stored function and DROP FUNCTION
breaks SBR".
Made enum_mdl_namespace enum part of MDL_key class and removed MDL_
prefix from the names of enum members. In order to do the latter
changed name of PROCEDURE symbol to PROCEDURE_SYM (otherwise macro
which was automatically generated for this symbol conflicted with
MDL_key::PROCEDURE enum member).
------------------------------------------------------------
revno: 2617.68.24
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg-pre2-2
timestamp: Wed 2009-09-16 17:25:29 +0400
message:
Pre-requisite patch for fixing bug #30977 "Concurrent statement
using stored function and DROP FUNCTION breaks SBR".
Added MDL_request for stored routine as member to Sroutine_hash_entry
in order to be able perform metadata locking for stored routines in
future (Sroutine_hash_entry is an equivalent of TABLE_LIST class for
stored routines).
(WL#4284, follow up fixes).
revno: 2617.68.23
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg-pre1
timestamp: Wed 2009-09-16 09:34:42 +0400
message:
Pre-requisite patch for fixing bug #30977 "Concurrent statement
using stored function and DROP FUNCTION breaks SBR".
CREATE TABLE SELECT statements take exclusive metadata lock on table
being created. Invariant of metadata locking subsystem states that
such lock should be taken before taking any kind of shared locks.
Once metadata locks on stored routines are introduced statements like
"CREATE TABLE ... SELECT f1()" will break this invariant by taking
shared locks on routines before exclusive lock on target table.
To avoid this, open_tables() is reworked to process tables which are
directly used by the statement before stored routines are processed.
------------------------------------------------------------
revno: 2617.68.10
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg46673
timestamp: Tue 2009-09-01 19:57:05 +0400
message:
Fix for bug #46673 "Deadlock between FLUSH TABLES WITH READ LOCK and DML".
Deadlocks occured when one concurrently executed transactions with
several statements modifying data and FLUSH TABLES WITH READ LOCK
statement or SET READ_ONLY=1 statement.
These deadlocks were introduced by the patch for WL 4284: "Transactional
DDL locking"/Bug 989: "If DROP TABLE while there's an active transaction,
wrong binlog order" which has changed FLUSH TABLES WITH READ LOCK/SET
READ_ONLY=1 to wait for pending transactions.
What happened was that FLUSH TABLES WITH READ LOCK blocked all further
statements changing tables by setting global_read_lock global variable
and has started waiting for all pending transactions to complete.
Then one of those transactions tried to executed DML, detected that
global_read_lock non-zero and tried to wait until global read lock will
be released (i.e. global_read_lock becomes 0), indeed, this led to a
deadlock.
Proper solution for this problem should probably involve full integration
of global read lock with metadata locking subsystem (which will allow to
implement waiting for pending transactions without blocking DML in them).
But since it requires significant changes another, short-term solution
for the problem is implemented in this patch.
Basically, this patch restores behavior of FLUSH TABLES WITH READ LOCK/
SET READ_ONLY=1 before the patch for WL 4284/bug 989. By ensuring that
extra references to TABLE_SHARE are not stored for active metadata locks
it changes these statements not to wait for pending transactions.
As result deadlock is eliminated.
Note that this does not change the fact that active FLUSH TABLES WITH
READ LOCK lock or SET READ_ONLY=1 prevent modifications to tables as
they also block transaction commits.
------------------------------------------------------------
revno: 2617.68.7
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg46044
timestamp: Thu 2009-08-27 10:22:17 +0400
message:
Fix for bug #46044 "MDL deadlock on LOCK TABLE + CREATE TABLE HIGH_PRIORITY
FOR UPDATE".
Deadlock occured when during execution of query to I_S we tried to open
a table or its .FRM in order to get information about it and had to wait
because we have encountered exclusive metadata lock on this table held by
a DDL operation from another connection which in its turn waited for some
resource currently owned by connection executing this I_S query.
For example, this might have happened if one under LOCK TABLES executed I_S
query targeted to particular table (which was not among locked) and also
concurrently tried to create this table using CREATE TABLE SELECT which
had to wait for one of tables locked by the first connection.
Another situation in which deadlock might have occured is when I_S query,
which was executed as part of transaction, tried to get information about
table which just has been dropped by concurrent DROP TABLES executed under
LOCK TABLES and this DROP TABLES for its completion also had to wait
transaction from the first connection.
This problem stemmed from the fact that opening of tables/.FRMs for I_S
filling is happening outside of connection's main MDL_context so code
which tries to detect deadlocks due to conflicting metadata locks doesn't
work in this case. Indeed, this led to deadlocks when during I_S filling
we tried to wait for conflicting metadata lock to go away, while its owner
was waiting for some resource held by connection executing I_S query.
This patch solves this problem by avoiding waiting in such situation.
Instead we skip this table and produce warning that information about
it was omitted from I_S due to concurrent DDL operation. We still wait
for conflicting metadata lock to go away when it is known that deadlock
is not possible (i.e. when connection executing I_S query does not hold
any metadata or table-level locks).
Basically, we apply our standard deadlock avoidance technique for metadata
locks to the process of filling of I_S tables but replace ER_LOCK_DEADLOCK
error with a warning.
Note that this change is supposed to be safe for 'mysqldump' since the
only its mode which is affected by this change is --single-transaction mode
is not safe in the presence of concurrent DDL anyway (and this fact is
documented). Other modes are unaffected because they either use
SHOW TABLES/SELECT * FROM I_S.TABLE_NAMES which do not take any metadata
locks in the process of I_S table filling and thus cannot skip tables or
execute I_S queries for tables which were previously locked by LOCK TABLES
(or in the presence of global read lock) which excludes possibility of
encountering conflicting metadata lock.
------------------------------------------------------------
revno: 2617.69.37
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-next-bg46748
timestamp: Fri 2009-08-21 18:17:02 +0400
message:
Fix for bug #46748 "Assertion in MDL_context::wait_for_locks()
on INSERT + CREATE TRIGGER".
Concurrent execution of statements involving stored functions or triggers
which were using several tables and DDL statements which affected those
tables on debug build of server might have led to assertion failures in
MDL_context::wait_for_locks(). Non-debug build was not affected.
The problem was that during back-off which happens when open_tables()
encounters conflicting metadata lock for one of the tables being open
we didn't reset MDL_request::ticket value for requests which correspond
to tables from extended prelocking set. Since these requests are part
of of list of requests to be waited for in Open_table_context this broke
assumption that ticket value for them is 0 in MDL_context::wait_for_locks()
and caused assertion failure.
This fix ensures that close_tables_for_reopen(), which performs this back-off
resets MDL_request::ticket value not only for tables directly used by the
statement but also for tables from extended prelocking set, thus satisfying
assumption described above.
Bug #47249 assert in MDL_global_lock::is_lock_type_compatible
This assert could be triggered if LOCK TABLES were used to lock
both a table and a view that used the same table. The table would have
to be first WRITE locked and then READ locked. So "LOCK TABLES v1
WRITE, t1 READ" would eventually trigger the assert, "LOCK TABLES
v1 READ, t1 WRITE" would not. The reason is that the ordering of locks
in the interal representation made a difference when executing
FLUSH TABLE on the table.
During FLUSH TABLE, a lock was upgraded to exclusive. If this lock
was of type MDL_SHARED and not MDL_SHARED_UPGRADABLE, an internal
counter in the MDL subsystem would get out of sync. This would happen
if the *last* mention of the table in LOCK TABLES was a READ lock.
The counter in question is the number exclusive locks (active or intention).
This is used to make sure a global metadata lock is only taken when the
counter is zero (= no conflicts). The counter is increased when a
MDL_EXCLUSIVE or MDL_SHARED_UPGRADABLE lock is taken, but not when
upgrade_shared_lock_to_exclusive() is used to upgrade directly
from MDL_SHARED to MDL_EXCLUSIVE.
This patch fixes the problem by searching for a TABLE instance locked
with MDL_SHARED_UPGRADABLE or MDL_EXCLUSIVE before calling
upgrade_shared_lock_to_exclusive(). The patch also adds an assert checking
that only MDL_SHARED_UPGRADABLE locks are upgraded to exclusive.
Test case added to lock_multi.test.
----------------------------------------------------------
revno: 2617.69.25
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-42546
timestamp: Fri 2009-08-14 23:52:00 +0400
message:
A cleanup in open_tables() and lock_tables():
change return type of these functions to bool from int,
to follow convention in the rest of the code.
(Part of WL#4284 review fixes).
A pre-requisite patch for Bug#30977 "Concurrent statement using
stored function and DROP FUNCTION breaks SBR".
This patch changes the MDL API by introducing a namespace for
lock keys: MDL_TABLE for tables and views and MDL_PROCEDURE
for stored procedures and functions. The latter is needed for
the fix for Bug#30977.
----------------------------------------------------------
revno: 2617.69.24
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-42546
timestamp: Fri 2009-08-14 19:22:05 +0400
message:
A pre-requisite for a fix for Bug#42546 "Backup: RESTORE fails, thinking it
finds an existing table"
Back-port from WL 148 "Foreign keys" feature tree a patch
that introduced Prelocking_strategy class -- a way to parameterize
open_tables() behaviour, implemented by Dmitry Lenev.
(Part of WL#4284).
----------------------------------------------------------
revno: 2617.69.20
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-4284-1-assert
timestamp: Thu 2009-08-13 18:29:55 +0400
message:
WL#4284 "Transactional DDL locking"
A review fix.
Since WL#4284 implementation separated MDL_request and MDL_ticket,
MDL_request becamse a utility object necessary only to get a ticket.
Store it by-value in TABLE_LIST with the intent to merge
MDL_request::key with table_list->table_name and table_list->db
in future.
Change the MDL subsystem to not require MDL_requests to
stay around till close_thread_tables().
Remove the list of requests from the MDL context.
Requests for shared metadata locks acquired in open_tables()
are only used as a list in recover_from_failed_open_table_attempt(),
which calls mdl_context.wait_for_locks() for this list.
To keep such list for recover_from_failed_open_table_attempt(),
introduce a context class (Open_table_context), that collects
all requests.
A lot of minor cleanups and simplications that became possible
with this change.
----------------------------------------------------------
revno: 2617.69.2
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-azalea-bugfixing
timestamp: Mon 2009-08-03 19:26:04 +0400
message:
A fix and a test case for Bug#45035 "Altering table under LOCK TABLES
results in "Error 1213 Deadlock found...".
If a user had a table locked with LOCK TABLES
for READ and for WRITE in the same connection, ALTER TABLE
could fail.
Root cause analysis:
If a connection issues
LOCK TABLE t1 write, t1 a read, t1 b read;
the new LOCK TABLES code in 6.0 (part of WL 3726) will create
the following list of TABLE_LIST objects
(thd->locked_tables_list->m_locked_tables):
{"t1" "b" tl_read_no_insert}, {"t1" "a" tl_read_no_insert},
{"t1" "t1" tl_write }
Later on, when we try to ALTER table t1, mysql_alter_table()
closes all TABLE instances and releases its thr_lock locks,
keeping only an exclusive metadata lock on t1.
But when ALTER is finished, Locked_table_list::reopen_tables()
tries to restore the original list of open and locked tables.
Before this patch, it used to do so one by one:
Open t1 b, get TL_READ_NO_INSERT lock,
Open t1 a, get TL_READ_NO_INSERT lock
Open t1, try to get TL_WRITE lock, deadlock.
The cause of the deadlock is that thr_lock.c doesn't
resolve the situation when the read list only consists
of locks taken by the same thread, followed by this very
thread trying to take a WRITE lock. Indeed, since
thr_lock_multi always gets a sorted list of locks,
WRITE locks always precede READ locks in the list
to lock.
Don't try to fix thr_lock.c deficiency, keep this
code simple.
Instead, try to take all thr_lock locks at once
in ::reopen_tables().
------------------------------------------------------------
revno: 2617.65.6
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-azalea-bg39674
timestamp: Sat 2009-07-25 00:28:43 +0400
message:
Fix for bug #39674 "On shutdown mdl_destroy() called before
plugin_shutdown()".
Attempt to shutdown PBXT engine plugin led to assertion failure
caused by using already destroyed mutex in metadata locking
subsystem.
This problem stemmed from the fact that we MDL subsystem and
table definition cache were deinitialized before plugin shutdown
while PBXT plugin during its shutdown process accessed tables and
therefore expected them to be in working shape.
This patch solves this problem by moving deinitialization of
these two subsystems after plugins are shut down.
No test case is provided since such test case would require
using PBXT or other plugin which accesses tables during its
shutdown process.
2617.31.12, 2617.31.15, 2617.31.15, 2617.31.16, 2617.43.1
- initial changeset that introduced the fix for
Bug#989 and follow up fixes for all test suite failures
introduced in the initial changeset.
------------------------------------------------------------
revno: 2617.31.1
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 4284-6.0
timestamp: Fri 2009-03-06 19:17:00 -0300
message:
Bug#989: If DROP TABLE while there's an active transaction, wrong binlog order
WL#4284: Transactional DDL locking
Currently the MySQL server does not keep metadata locks on
schema objects for the duration of a transaction, thus failing
to guarantee the integrity of the schema objects being used
during the transaction and to protect then from concurrent
DDL operations. This also poses a problem for replication as
a DDL operation might be replicated even thought there are
active transactions using the object being modified.
The solution is to defer the release of metadata locks until
a active transaction is either committed or rolled back. This
prevents other statements from modifying the table for the
entire duration of the transaction. This provides commitment
ordering for guaranteeing serializability across multiple
transactions.
- Incompatible change:
If MySQL's metadata locking system encounters a lock conflict,
the usual schema is to use the try and back-off technique to
avoid deadlocks -- this schema consists in releasing all locks
and trying to acquire them all in one go.
But in a transactional context this algorithm can't be utilized
as its not possible to release locks acquired during the course
of the transaction without breaking the transaction commitments.
To avoid deadlocks in this case, the ER_LOCK_DEADLOCK will be
returned if a lock conflict is encountered during a transaction.
Let's consider an example:
A transaction has two statements that modify table t1, then table
t2, and then commits. The first statement of the transaction will
acquire a shared metadata lock on table t1, and it will be kept
utill COMMIT to ensure serializability.
At the moment when the second statement attempts to acquire a
shared metadata lock on t2, a concurrent ALTER or DROP statement
might have locked t2 exclusively. The prescription of the current
locking protocol is that the acquirer of the shared lock backs off
-- gives up all his current locks and retries. This implies that
the entire multi-statement transaction has to be rolled back.
- Incompatible change:
FLUSH commands such as FLUSH PRIVILEGES and FLUSH TABLES WITH READ
LOCK won't cause locked tables to be implicitly unlocked anymore.
----------------------------------------------------------
revno: 2617.23.20
committer: Konstantin Osipov <kostja@sun.com>
branch nick: mysql-6.0-runtime
timestamp: Wed 2009-03-04 16:31:31 +0300
message:
WL#4284 "Transactional DDL locking"
Review comments: "Objectify" the MDL API.
MDL_request and MDL_context still need manual construction and
destruction, since they are used in environment that is averse
to constructors/destructors.
------------------------------------------------------------
revno: 2617.23.18
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 4284-6.0
timestamp: Mon 2009-03-02 18:18:26 -0300
message:
Bug#989: If DROP TABLE while there's an active transaction, wrong binlog order
WL#4284: Transactional DDL locking
This is a prerequisite patch:
These changes are intended to split lock requests from granted
locks and to allow the memory and lifetime of granted locks to
be managed within the MDL subsystem. Furthermore, tickets can
now be shared and therefore are used to satisfy multiple lock
requests, but only shared locks can be recursive.
The problem is that the MDL subsystem morphs lock requests into
granted locks locks but does not manage the memory and lifetime
of lock requests, and hence, does not manage the memory of
granted locks either. This can be problematic because it puts the
burden of tracking references on the users of the subsystem and
it can't be easily done in transactional contexts where the locks
have to be kept around for the duration of a transaction.
Another issue is that recursive locks (when the context trying to
acquire a lock already holds a lock on the same object) requires
that each time the lock is granted, a unique lock request/granted
lock structure structure must be kept around until the lock is
released. This can lead to memory leaks in transactional contexts
as locks taken during the transaction should only be released at
the end of the transaction. This also leads to unnecessary wake
ups (broadcasts) in the MDL subsystem if the context still holds
a equivalent of the lock being released.
These issues are exacerbated due to the fact that WL#4284 low-level
design says that the implementation should "2) Store metadata locks
in transaction memory root, rather than statement memory root" but
this is not possible because a memory root, as implemented in mysys,
requires all objects allocated from it to be freed all at once.
This patch combines review input and significant code contributions
from Konstantin Osipov (kostja) and Dmitri Lenev (dlenev).
------------------------------------------------------------
revno: 2630.22.3
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 4284-6.0
timestamp: Thu 2008-08-07 22:33:43 -0300
message:
WL#4284: Transactional DDL locking
Make transaction management more modular through a new interface.
The overall objective of this change is to provide groundwork
for the design of transactional DDL locking by cleaning up the
transaction high level API to better distinguish operations implicit
and explicit, and single statement transaction from operations on
the normal transaction.
Having a a high-level interface for transaction management provides
a better base for implementing transactional concepts that are not
always tied to storage engines and also makes it easier to interect
with other higher level modules of the server.
----------------------------------------------------------
revno: 2630.4.38
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-4144
timestamp: Wed 2008-06-25 22:07:06 +0400
message:
WL#4144 - Lock MERGE engine children.
Committing a version of the patch merged with WL#3726
on behalf of Ingo.
Step #1: Move locking from parent to children.
MERGE children are now left in the query list of tables
after inserted there in open_tables(). So they are locked
by lock_tables() as all other tables are.
The MERGE parent does not store locks any more. It appears
in a MYSQL_LOCK with zero lock data. This is kind of a "dummy"
lock.
All other lock handling is also done directly on the children.
To protect against parent or child modifications during LOCK
TABLES, the children are detached after every statement and
attached before every statement, even under LOCK TABLES.
The children table list is removed from the query list of tables
on every detach and on close of the parent.
Step #2: Move MERGE specific functionality from SQL layer
into table handler.
Functionality moved from SQL layer (mainly sql_base.cc)
to the table handler (ha_myisammrg.cc).
Unnecessary code is removed from the SQL layer.
Step #3: Moved all MERGE specific members from TABLE
to ha_myisammrg.
Moved members from TABLE to ha_myisammrg.
Renamed some mebers.
Fixed comments.
Step #4: Valgrind and coverage testing
Valgrind did not uncover new problems.
Added purecov comments.
Added a new test for DATA/INDEX DIRECTORY options.
Changed handling of ::reset() for non-attached children.
Fixed the merge-big test.
Step #5: Fixed crashes detected during review
Changed detection when to attach/detach.
Added new tests.
Backport also the fix for Bug#44040 "MySQL allows creating a
MERGE table upon VIEWs but crashes when using it"
----------------------------------------------------------
revno: 2630.4.36
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-3726
timestamp: Wed 2008-06-25 17:03:37 +0400
message:
As per discussion with Serg and Dmitri, remove the code
that is trying to emulate LOCK TABLES when locking tables for prelocking.
This code was worked around by the engines, and has no effect.
We may still have to do something to ensure that statement-based
replication is consistent in MVCC engines, or other engines
that downgrade table level locks, but this will have to be done
somehow differently.
------------------------------------------------------------
revno: 2630.4.33
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Fri 2008-06-20 17:11:20 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After-review fixes in progress.
Minimized dependency of mdl.cc on other modules (particularly
made it independant of mysql_priv.h) in order to be able
write unit tests for metadata locking subsystem.
----------------------------------------------------------
revno: 2630.4.31
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-3726
timestamp: Thu 2008-06-12 06:23:08 +0400
message:
Extend the signature of TABLE_LIST::init_one_table() to
initialize lengths
This is part of WL#3726 post-review fixes.
----------------------------------------------------------
revno: 2630.10.1
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-lock-tables-tidyup
timestamp: Wed 2008-06-11 15:49:58 +0400
message:
WL#3726, review fixes.
Now that we have metadata locks, we don't need to keep a crippled
TABLE instance in the table cache to indicate that a table is locked.
Remove all code that used this technique. Instead, rely on metadata
locks and use the standard open_table() and close_thread_table()
to manipulate with the table cache tables.
Removes a list of functions that have become unused (see the comment
for sql_base.cc for details).
Under LOCK TABLES, keep a TABLE_LIST instance for each table
that may be temporarily closed. For that, implement an own class for
LOCK TABLES mode, Locked_tables_list.
This is a pre-requisite patch for WL#4144.
This is not exactly a backport: there is no new
online ALTER table in Celosia, so the old alter table
code was changed to work with the new table cache API.
------------------------------------------------------------
revno: 2630.9.3
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w3
timestamp: Wed 2008-06-11 08:33:36 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
Changed close_cached_tables() not to flush all unused TABLE
instances when flushing individual table.
Renamed expel_table_from_cache() to tdc_remove_table() and
added enum parameter to be able more explicitly specify type
of removal, rewrote its code to be more efficient.
******
Backport of:
------------------------------------------------------------
revno: 2630.9.4
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w3
timestamp: Wed 2008-06-11 15:53:53 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After-review fixes in progress.
Minor changes in order to improve code readability
and simplify debugging.
Text conflict in mysql-test/collections/default.experimental
Text conflict in mysql-test/r/show_check.result
Text conflict in mysql-test/r/sp-code.result
Text conflict in mysql-test/suite/binlog/r/binlog_tmp_table.result
Text conflict in mysql-test/suite/rpl/t/disabled.def
Text conflict in mysql-test/t/show_check.test
Text conflict in mysys/my_delete.c
Text conflict in sql/item.h
Text conflict in sql/item_cmpfunc.h
Text conflict in sql/log.cc
Text conflict in sql/mysqld.cc
Text conflict in sql/repl_failsafe.cc
Text conflict in sql/slave.cc
Text conflict in sql/sql_parse.cc
Text conflict in sql/sql_table.cc
Text conflict in sql/sql_yacc.yy
Text conflict in storage/myisam/ha_myisam.cc
Corrected results for
stm_auto_increment_bug33029.reject 2009-12-01
20:01:49.000000000 +0300
<andrei> @@ -42,9 +42,6 @@
<andrei> RETURN i;
<andrei> END//
<andrei> CALL p1();
<andrei> -Warnings:
<andrei> -Note 1592 Statement may not be safe to log in statement
format.
<andrei> -Note 1592 Statement may not be safe to log in statement
format.
There should be indeed no Note present because there is in fact autoincrement
top-level query in sp() that triggers inserting in yet another auto-inc table.
(todo: alert DaoGang to improve the test).
------------------------------------------------------------
revno: 2630.9.1
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w3
timestamp: Sun 2008-06-08 22:13:58 +0400
message:
WL#3726 "DDL locking for all metadata objects"
After review fixes in progress.
Some adjustments to the patch that removes thd->locked_tables
------------------------------------------------------------
revno: 2630.4.27
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Mon 2008-06-09 14:01:19 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
Changed open_table() to return bool. This allows more easily to
distinguish cases when this function succeeds but returns no TABLE
instance (in case of view or in case of special kind of open) from
cases when we have an error. Pointer to TABLE instance is now
always returned in TABLE_LIST::table member.
This change allows to get rid of false assumption in open_tables()
implementation and makes it more clear.
----------------------------------------------------------
revno: 2630.4.26
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-prelocked_mode-to-push
timestamp: Fri 2008-06-06 23:19:04 +0400
message:
WL#3726: work on review comments.
Remove thd->locked_tables. Always store MYSQL_LOCK instances in
thd->lock.
Rename thd->prelocked_mode to thd->locked_tables_mode.
Use thd->locked_tables_mode to determine if we
are under LOCK TABLES. Update the code to not assume that
if thd->lock is set, LOCK TABLES mode is off.
Review comments.
------------------------------------------------------------
revno: 2630.4.24
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Fri 2008-06-06 14:28:58 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
Get rid of upgradability and priority attributes of
metadata lock requests by replacing them with two
new types of lock requests MDL_SHARED_UPGRADABLE and
MDL_SHARED_HIGH_PRIO correspondingly.
------------------------------------------------------------
revno: 2630.8.3
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w4
timestamp: Thu 2008-06-05 10:48:36 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After-review fixes in progress.
Adjust some comments that were using old terminology
(name locks instead of exclusive metadata locks), brought
some of them up-to-date with current situation in code.
------------------------------------------------------------
revno: 2630.4.20
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Wed 2008-06-04 16:27:06 +0400
message:
WL#3726 "DDL locking for all metadata objects"
After review fixes in progress.
Got rid of TABLE_LIST::mdl_upgradable member and related functions
by using special flag which to be passed to open_table() which
asks it to take upgradable metadata lock on table being opened.
---------------------------------------------
2630.7.3 Konstantin Osipov 2008-06-02
Various style changes preceding the removal of reopen_table().
(Post-review fixes for WL#3726).
------------------------------------------------------------
revno: 2630.4.18
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Tue 2008-06-03 21:07:58 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
Now during upgrading/downgrading metadata locks we deal with
individual metadata lock requests rather than with all requests
for this object in the context. This makes API a bit more clear
and makes adjust_mdl_locks_upgradability() much nicer.
------------------------------------------------------------
revno: 2630.4.17
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Thu 2008-05-29 16:52:56 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
"The great correction of names".
Renamed MDL_LOCK and MDL_LOCK_DATA classes to make usage of
these names in metadata locking subsystem consistent with
other parts of server (i.e. thr_lock.cc). Now we MDL_LOCK_DATA
corresponds to request for a lock and MDL_LOCK to the lock
itself. Adjusted code in MDL subsystem and other places
using these classes accordingly.
Did similar thing for GLOBAL_MDL_LOCK_DATA class and also
changed name of its members to correspond to names of
MDL_LOCK_DATA members.
Finally got rid of usage of one letter variables in MDL
code since it makes code harder to search in (according
to reviewer).
------------------------------------------------------------
revno: 2630.4.16
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Thu 2008-05-29 09:45:02 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review changes in progress.
Tweaked some comments and did some renames to
avoid ambiguites.
------------------------------------------------------------
revno: 2630.4.14
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Wed 2008-05-28 12:16:03 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress. Removed unused code and
adjusted names of functions/methods to better reflect
their current function.
------------------------------------------------------------
revno: 2630.4.13
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Wed 2008-05-28 12:07:30 +0400
message:
WL#3726 "DDL locking for all metadata objects".
After review fixes in progress.
Get rid of remove_table_from_cache() function since it was
doing two things at once -- waiting while no one uses particular
table (now job of metadata locking) and removing TABLE/TABLE_SHARE
instances from table definition cache (now job of
expel_table_from_cache()).
