------------------------------------------------------------
2599.161.3 Ingo Struewing 2009-07-21
Bug#20667 - Truncate table fails for a write locked table
TRUNCATE TABLE was not allowed under LOCK TABLES.
The patch removes this restriction. mysql_truncate()
does now handle that case.
mysql-test/r/merge.result:
Bug#20667 - Truncate table fails for a write locked table
Updated test result.
mysql-test/r/truncate.result:
Bug#20667 - Truncate table fails for a write locked table
Updated test result.
mysql-test/r/truncate_coverage.result:
Bug#20667 - Truncate table fails for a write locked table
New test result.
mysql-test/t/merge.test:
Bug#20667 - Truncate table fails for a write locked table
Updated test case due to now working TRUNCATE under LOCK TABLES.
Added some SELECTs to show that child tables are truncated.
mysql-test/t/truncate.test:
Bug#20667 - Truncate table fails for a write locked table
Added test cases for TRUNCATE under LOCK TABLE.
mysql-test/t/truncate_coverage.test:
Bug#20667 - Truncate table fails for a write locked table
New test file. Coverage tests for TRUNCATE.
sql/sql_delete.cc:
Bug#20667 - Truncate table fails for a write locked table
Added branches for thd->locked_tables_mode.
sql/sql_parse.cc:
Bug#20667 - Truncate table fails for a write locked table
Deleted rejection of TRUNCATE in case of LOCK TABLES.
------------------------------------------------------------
2599.161.3 Ingo Struewing 2009-07-21
Bug#20667 - Truncate table fails for a write locked table
TRUNCATE TABLE was not allowed under LOCK TABLES.
The patch removes this restriction. mysql_truncate()
does now handle that case.
Bug #48210 FLUSH TABLES WITH READ LOCK deadlocks
against concurrent CREATE PROCEDURE
This deadlock occured between
a) CREATE PROCEDURE (or other commands listed below)
b) FLUSH TABLES WITH READ LOCK
If the execution of them happened in the following order:
- a) opens a table (e.g. mysql.proc)
- b) locks the global read lock (or GRL)
- a) sleeps inside wait_if_global_read_lock()
- b) increases refresh_version and sleeps waiting
for old tables to go away
Note that a) must start waiting on the GRL before FLUSH increases
refresh_version. Otherwise a) won't wait on the GRL and instead
close its tables for reopen, allowing FLUSH to complete and thus
avoid the deadlock.
With this patch the deadlock is avoided by making CREATE PROCEDURE
acquire a protection against global read locks before it starts
executing. This means that FLUSH TABLES WITH READ LOCK will have
to wait until CREATE PROCEDURE completes before acquiring the global
read lock, thereby avoiding the deadlock.
This is implemented by introducing a new SQL command flag called
CF_PROTECT_AGAINST_GRL. Commands marked with this flag will
acquire a GRL protection in the beginning of mysql_execute_command().
This patch adds the flag to CREATE, ALTER and DROP for PROCEDURE
and FUNCTION, as well as CREATE USER, DROP USER, RENAME USER and
REVOKE ALL. All these commands either call open_grant_tables() or
open_system_table_for_updated() which make them susceptible for
this deadlock.
The patch also adds the CF_PROTECT_AGAINST_GRL flag to a number
of commands that previously acquired GRL protection in their
respective SQLCOM case in mysql_execute_command().
Test case that checks for GRL protection for CREATE PROCEDURE
and CREATE USER added to mdl_sync.test.
Bug #48210 FLUSH TABLES WITH READ LOCK deadlocks
against concurrent CREATE PROCEDURE
This deadlock occured between
a) CREATE PROCEDURE (or other commands listed below)
b) FLUSH TABLES WITH READ LOCK
If the execution of them happened in the following order:
- a) opens a table (e.g. mysql.proc)
- b) locks the global read lock (or GRL)
- a) sleeps inside wait_if_global_read_lock()
- b) increases refresh_version and sleeps waiting
for old tables to go away
Note that a) must start waiting on the GRL before FLUSH increases
refresh_version. Otherwise a) won't wait on the GRL and instead
close its tables for reopen, allowing FLUSH to complete and thus
avoid the deadlock.
With this patch the deadlock is avoided by making CREATE PROCEDURE
acquire a protection against global read locks before it starts
executing. This means that FLUSH TABLES WITH READ LOCK will have
to wait until CREATE PROCEDURE completes before acquiring the global
read lock, thereby avoiding the deadlock.
This is implemented by introducing a new SQL command flag called
CF_PROTECT_AGAINST_GRL. Commands marked with this flag will
acquire a GRL protection in the beginning of mysql_execute_command().
This patch adds the flag to CREATE, ALTER and DROP for PROCEDURE
and FUNCTION, as well as CREATE USER, DROP USER, RENAME USER and
REVOKE ALL. All these commands either call open_grant_tables() or
open_system_table_for_updated() which make them susceptible for
this deadlock.
The patch also adds the CF_PROTECT_AGAINST_GRL flag to a number
of commands that previously acquired GRL protection in their
respective SQLCOM case in mysql_execute_command().
Test case that checks for GRL protection for CREATE PROCEDURE
and CREATE USER added to mdl_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.
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.
An assert in reload_acl_and_cache didn't account for the
case when the function is called with a NULL thd. A
null thd is used whenever the function is called from the
SIGHUP signal handler.
Backported from 6.0-codebase (revid: 2617.69.35)
An assert in reload_acl_and_cache didn't account for the
case when the function is called with a NULL thd. A
null thd is used whenever the function is called from the
SIGHUP signal handler.
Backported from 6.0-codebase (revid: 2617.69.35)
------------------------------------------------------------
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: 2617.68.25
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).
Introduce a counter for protection against global read lock on thread level.
The functions for protection against global read lock sometimes need a local
variable to signal when the protection is set, and hence need to be released.
It would be better to control this behaviour via a counter on the THD struct,
telling how many times the protection has been claimed by the current thread.
A side-effect of the fix is that if protection is claimed twice for a thread,
only a simple increment is required for the second claim, instead of a
mutex-protected increment of the global variable protect_against_global_read_lock.
sql/lock.cc:
Count how many times that we have claimed protection against global read lock.
Assert that we really have the protection when releasing it.
Added comments to all functions operating on global_read_lock.
sql/sql_class.cc:
Added the counter variable global_read_lock_protection.
sql/sql_class.h:
Added the counter variable global_read_lock_protection.
sql/sql_parse.cc:
Replaced test on local variable need_start_waiting with test on
thd->global_read_lock_protection.
sql/sql_table.cc:
Replaced test on local variable need_start_waiting with test on
thd->global_read_lock_protection.
sql/sql_trigger.cc:
Inserted test on thd->global_read_lock_protection.
Introduce a counter for protection against global read lock on thread level.
The functions for protection against global read lock sometimes need a local
variable to signal when the protection is set, and hence need to be released.
It would be better to control this behaviour via a counter on the THD struct,
telling how many times the protection has been claimed by the current thread.
A side-effect of the fix is that if protection is claimed twice for a thread,
only a simple increment is required for the second claim, instead of a
mutex-protected increment of the global variable protect_against_global_read_lock.
Bug #21793 Missing CF_CHANGES_DATA and CF_STATUS_COMMAND for
handful of commands
CF_CHANGES_DATA and CF_STATUS_COMMAND flags added to the
commands mentioned in the bug description. With the following
two exceptions:
1) 4 commands do not exist:
SQLCOM_RENAME_DB
SQLCOM_LOAD_MASTER_DATA
SQLCOM_LOAD_MASTER_TABLE
SQLCOM_SHOW_COLUMN_TYPES
2) All SQLCOM_SHOW_* commands already had CF_STATUS_COMMAND,
leaving only SQLCOM_BINLOG_BASE64_EVENT.
Further, check_prepared_statement() in sql_prepare.cc has been
simplified by taking advantage of the CF_STATUS_COMMAND flag.
Note that no test case has been added.
Bug #21793 Missing CF_CHANGES_DATA and CF_STATUS_COMMAND for
handful of commands
CF_CHANGES_DATA and CF_STATUS_COMMAND flags added to the
commands mentioned in the bug description. With the following
two exceptions:
1) 4 commands do not exist:
SQLCOM_RENAME_DB
SQLCOM_LOAD_MASTER_DATA
SQLCOM_LOAD_MASTER_TABLE
SQLCOM_SHOW_COLUMN_TYPES
2) All SQLCOM_SHOW_* commands already had CF_STATUS_COMMAND,
leaving only SQLCOM_BINLOG_BASE64_EVENT.
Further, check_prepared_statement() in sql_prepare.cc has been
simplified by taking advantage of the CF_STATUS_COMMAND flag.
Note that no test case has been added.
Bug #47107 assert in notify_shared_lock on incorrect CREATE TABLE , HANDLER
Attempts to create a table (using CREATE TABLE, CREATE TABLE LIKE or
CREATE TABLE SELECT statements) which already existed and was opened
by the same connection through HANDLER statement, led to a stalled
connection (for production builds of the server) or to the server being
aborted due to an assertion failure (for debug builds of the server).
This problem was introduced by the new implementation of a metadata
locking subsystem and didn't affect earlier versions of the server.
The cause of the problem was that the HANDLER was not closed by CREATE TABLE
before CREATE tried to open and lock the table. Acquiring an exclusive MDL
lock on the table to be created would therefore fail since HANDLER
already had a shared MDL lock. This triggered an assert as the
HANDLER and CREATE statements came from the same thread (self-deadlock).
This patch resolves the issue by closing any open HANDLERs on tables
to be created by CREATE TABLE, similar to what is already done for
DROP and ALTER TABLE.
Test case added to create.test.
Bug #47107 assert in notify_shared_lock on incorrect CREATE TABLE , HANDLER
Attempts to create a table (using CREATE TABLE, CREATE TABLE LIKE or
CREATE TABLE SELECT statements) which already existed and was opened
by the same connection through HANDLER statement, led to a stalled
connection (for production builds of the server) or to the server being
aborted due to an assertion failure (for debug builds of the server).
This problem was introduced by the new implementation of a metadata
locking subsystem and didn't affect earlier versions of the server.
The cause of the problem was that the HANDLER was not closed by CREATE TABLE
before CREATE tried to open and lock the table. Acquiring an exclusive MDL
lock on the table to be created would therefore fail since HANDLER
already had a shared MDL lock. This triggered an assert as the
HANDLER and CREATE statements came from the same thread (self-deadlock).
This patch resolves the issue by closing any open HANDLERs on tables
to be created by CREATE TABLE, similar to what is already done for
DROP and ALTER TABLE.
Test case added to create.test.
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.
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).
sql/sql_base.cc:
Implement different prelocking strategies. Use an instance of
prelocking_strategy in open_tables().
sql/sql_class.h:
Add declarations for class Prelocking_strategy.
sql/sql_lex.h:
Add a helper method to access last table of the global table list
(lex->query_tables).
sql/sql_parse.cc:
Use a special prelocking strategy when locking tables for LOCK TABLES.
sql/sql_table.cc:
Use normal open_and_lock_tables_derived() in ALTER TABLE.
sql/sql_yacc.yy:
Modify the grammar to not pollute the global table list with tables
that should not be opened.
----------------------------------------------------------
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.
sql/event_db_repository.cc:
Remove alloc_mdl_requests(). Now MDL_request instance is a member
of TABLE_LIST, and init_one_table() initializes it.
sql/ha_ndbcluster_binlog.cc:
Remove now unnecessary declaration and initialization
of binlog_mdl_request.
sql/lock.cc:
No need to allocate MDL requests in lock_table_names() now.
sql/log.cc:
Use init_one_table() method, remove alloc_mdl_requests(),
which is now unnecessary.
sql/log_event.cc:
No need to allocate mdl_request separately now.
Use init_one_table() method.
sql/log_event_old.cc:
Update to the new signature of close_tables_for_reopen().
sql/mdl.cc:
Update try_acquire_exclusive_lock() to be more easy to use.
Function lock_table_name_if_not_cached() has been removed.
Make acquire_shared_lock() signature consistent with
try_acquire_exclusive_lock() signature.
Remove methods that are no longer used.
Update comments.
sql/mdl.h:
Implement an assignment operator that doesn't
copy MDL_key (MDL_key::operator= is private and
should remain private).
This is a hack to work-around assignment of TABLE_LIST
by value in several places. Such assignments violate
encapsulation, since only perform a shallow copy.
In most cases these assignments are a hack on their own.
sql/mysql_priv.h:
Update signatures of close_thread_tables() and close_tables_for_reopen().
sql/sp.cc:
Allocate TABLE_LIST in thd->mem_root.
Use init_one_table().
sql/sp_head.cc:
Use init_one_table().
Remove thd->locked_tables_root, it's no longer needed.
sql/sql_acl.cc:
Use init_mdl_requests() and init_one_table().
sql/sql_base.cc:
Update to new signatures of try_acquire_shared_lock() and
try_acquire_exclusive_lock().
Remove lock_table_name_if_not_cached().
Fix a bug in open_ltable() that would not return ER_LOCK_DEADLOCK
in case of a failed lock_tables() and a multi-statement
transaction.
Fix a bug in open_and_lock_tables_derived() that would
not return ER_LOCK_DEADLOCK in case of a multi-statement
transaction and a failure of lock_tables().
Move assignment of enum_open_table_action to a method of Open_table_context, a new class that maintains information
for backoff actions.
Minor rearrangements of the code.
Remove alloc_mdl_requests() in functions that work with system
tables: instead the patch ensures that callers always initialize
TABLE_LIST argument.
sql/sql_class.cc:
THD::locked_tables_root is no more.
sql/sql_class.h:
THD::locked_tables_root is no more.
Add a declaration for Open_table_context class.
sql/sql_delete.cc:
Update to use the simplified MDL API.
sql/sql_handler.cc:
TABLE_LIST::mdl_request is stored by-value now.
Ensure that mdl_request.ticket is NULL for every request
that is passed into MDL, to satisfy MDL asserts.
@ sql/sql_help.cc
Function open_system_tables_for_read() no longer initializes
mdl_requests.
Move TABLE_LIST::mdl_request initialization closer to
TABLE_LIST initialization.
sql/sql_help.cc:
Function open_system_tables_for_read() no longer initializes
mdl_requests.
Move TABLE_LIST::mdl_request initialization closer to
TABLE_LIST initialization.
sql/sql_insert.cc:
Remove assignment by-value of TABLE_LIST in
TABLEOP_HOOKS. We can't carry over a granted
MDL ticket from one table list to another.
sql/sql_parse.cc:
Change alloc_mdl_requests() -> init_mdl_requests().
@todo We can remove init_mdl_requests() altogether
in some places: all places that call add_table_to_list()
already have mdl requests initialized.
sql/sql_plugin.cc:
Use init_one_table().
THD::locked_tables_root is no more.
sql/sql_servers.cc:
Use init_one_table().
sql/sql_show.cc:
Update acquire_high_priority_shared_lock() to use
TABLE_LIST::mdl_request rather than allocate an own.
Fix get_trigger_table_impl() to use init_one_table(),
check for out of memory, follow the coding style.
sql/sql_table.cc:
Update to work with TABLE_LIST::mdl_request by-value.
Remove lock_table_name_if_not_cached().
The code that used to delegate to it is quite simple and
concise without it now.
sql/sql_udf.cc:
Use init_one_table().
sql/sql_update.cc:
Update to use the new signature of close_tables_for_reopen().
sql/table.cc:
Move re-setting of mdl_requests for prepared statements
and stored procedures from close_thread_tables() to
reinit_stmt_before_use().
Change alloc_mdl_requests() to init_mdl_requests().
init_mdl_requests() is a hack that can't be deleted
until we don't have a list-aware TABLE_LIST constructor.
Hopefully its use will be minimal
sql/table.h:
Change alloc_mdl_requests() to init_mdl_requests()
TABLE_LIST::mdl_request is stored by value.
sql/tztime.cc:
We no longer initialize mdl requests in open_system_tables_for*()
functions. Move this initialization closer to initialization
of the rest of TABLE_LIST members.
storage/myisammrg/ha_myisammrg.cc:
Simplify mdl_request initialization.
----------------------------------------------------------
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.
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.
mysql-test/extra/binlog_tests/drop_table.test:
Add test case for Bug#989.
mysql-test/extra/binlog_tests/mix_innodb_myisam_binlog.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/include/mix1.inc:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/include/mix2.inc:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/r/flush_block_commit.result:
Update test case result (WL#4284).
mysql-test/r/flush_block_commit_notembedded.result:
Update test case result (WL#4284).
mysql-test/r/innodb.result:
Update test case result (WL#4284).
mysql-test/r/innodb_mysql.result:
Update test case result (WL#4284).
mysql-test/r/lock.result:
Add test case result for an effect of WL#4284/Bug#989
(all locks should be released when a connection terminates).
mysql-test/r/mix2_myisam.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/r/not_embedded_server.result:
Update test case result (effects of WL#4284/Bug#989).
Add a test case for interaction of WL#4284 and FLUSH PRIVILEGES.
mysql-test/r/partition_innodb_semi_consistent.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/r/partition_sync.result:
Temporarily disable the test case for Bug#43867,
which will be fixed by a subsequent backport.
mysql-test/r/ps.result:
Add a test case for effect of PREPARE on transactional
locks: we take a savepoint at beginning of PREAPRE
and release it at the end. Thus PREPARE does not
accumulate metadata locks (Bug#989/WL#4284).
mysql-test/r/read_only_innodb.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_row_drop_tbl.result:
Add a test case result (WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_row_mix_innodb_myisam.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_stm_drop_tbl.result:
Add a test case result (WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result:
Update test case result (effects of WL#4284/Bug#989).
mysql-test/suite/binlog/r/binlog_unsafe.result:
A side effect of Bug#989 -- slightly different table map ids.
mysql-test/suite/binlog/t/binlog_row_drop_tbl.test:
Add a test case for WL#4284/Bug#989.
mysql-test/suite/binlog/t/binlog_stm_drop_tbl.test:
Add a test case for WL#4284/Bug#989.
mysql-test/suite/binlog/t/binlog_stm_row.test:
Update to the new state name. This
is actually a follow up to another patch for WL#4284,
that changes Locked thread state to Table lock.
mysql-test/suite/ndb/r/ndb_index_ordered.result:
Remove result for disabled part of the test case.
mysql-test/suite/ndb/t/disabled.def:
Temporarily disable a test case (Bug#45621).
mysql-test/suite/ndb/t/ndb_index_ordered.test:
Disable a part of a test case (needs update to
reflect semantics of Bug#989).
mysql-test/suite/rpl/t/disabled.def:
Disable tests made meaningless by transactional metadata
locking.
mysql-test/suite/sys_vars/r/autocommit_func.result:
Add a commit (Bug#989).
mysql-test/suite/sys_vars/t/autocommit_func.test:
Add a commit (Bug#989).
mysql-test/t/flush_block_commit.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
mysql-test/t/flush_block_commit_notembedded.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction.
Add a test case for transaction-scope locks and the global
read lock (Bug#989/WL#4284).
mysql-test/t/innodb.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction
(effects of Bug#989/WL#4284).
mysql-test/t/lock.test:
Add a test case for Bug#989/WL#4284.
mysql-test/t/not_embedded_server.test:
Add a test case for Bug#989/WL#4284.
mysql-test/t/partition_innodb_semi_consistent.test:
Replace TRUNCATE with DELETE, to not issue
an implicit commit of a transaction, and not depend
on metadata locks.
mysql-test/t/partition_sync.test:
Temporarily disable the test case for Bug#43867,
which needs a fix to be backported from 6.0.
mysql-test/t/ps.test:
Add a test case for semantics of PREPARE and transaction-scope
locks: metadata locks on tables used in PREPARE are enclosed into a
temporary savepoint, taken at the beginning of PREPARE,
and released at the end. Thus PREPARE does not effect
what locks a transaction owns.
mysql-test/t/read_only_innodb.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction
(Bug#989/WL#4284).
Wait for the read_only statement to actually flush tables before
sending other concurrent statements that depend on its state.
mysql-test/t/xa.test:
Fix test case to reflect the fact that transactions now hold
metadata locks for the duration of a transaction
(Bug#989/WL#4284).
sql/ha_ndbcluster_binlog.cc:
Backport bits of changes of ha_ndbcluster_binlog.cc
from 6.0, to fix the failing binlog test suite with
WL#4284. WL#4284 implementation does not work
with 5.1 implementation of ndbcluster binlog index.
sql/log_event.cc:
Release metadata locks after issuing a commit.
sql/mdl.cc:
Style changes (WL#4284).
sql/mysql_priv.h:
Rename parameter to match the name used in the definition (WL#4284).
sql/rpl_injector.cc:
Release metadata locks on commit (WL#4284).
sql/rpl_rli.cc:
Remove assert made meaningless, metadata locks are released
at the end of the transaction.
sql/set_var.cc:
Close tables and release locks if autocommit mode is set.
sql/slave.cc:
Release metadata locks after a rollback.
sql/sql_acl.cc:
Don't implicitly unlock locked tables. Issue a implicit commit
at the end and unlock tables.
sql/sql_base.cc:
Defer the release of metadata locks when closing tables
if not required to.
Issue a deadlock error if the locking protocol requires
that a transaction re-acquire its locks.
Release metadata locks when closing tables for reopen.
sql/sql_class.cc:
Release metadata locks if the thread is killed.
sql/sql_parse.cc:
Release metadata locks after implicitly committing a active
transaction, or after explicit commits or rollbacks.
sql/sql_plugin.cc:
Allocate MDL request on the stack as the use of the table
is contained within the function. It will be removed from
the context once close_thread_tables is called at the end
of the function.
sql/sql_prepare.cc:
The problem is that the prepare phase of the CREATE TABLE
statement takes a exclusive metadata lock lock and this can
cause a self-deadlock the thread already holds a shared lock
on the table being that should be created.
The solution is to make the prepare phase take a shared
metadata lock when preparing a CREATE TABLE statement. The
execution of the statement will still acquire a exclusive
lock, but won't cause any problem as it issues a implicit
commit.
After some discussions with stakeholders it has been decided that
metadata locks acquired during a PREPARE statement must be released
once the statement is prepared even if it is prepared within a multi
statement transaction.
sql/sql_servers.cc:
Don't implicitly unlock locked tables. Issue a implicit commit
at the end and unlock tables.
sql/sql_table.cc:
Close table and release metadata locks after a admin operation.
sql/table.h:
The problem is that the prepare phase of the CREATE TABLE
statement takes a exclusive metadata lock lock and this can
cause a self-deadlock the thread already holds a shared lock
on the table being that should be created.
The solution is to make the prepare phase take a shared
metadata lock when preparing a CREATE TABLE statement. The
execution of the statement will still acquire a exclusive
lock, but won't cause any problem as it issues a implicit
commit.
sql/transaction.cc:
Release metadata locks after the implicitly committed due
to a new transaction being started. Also, release metadata
locks acquired after a savepoint if the transaction is rolled
back to the save point.
The problem is that in some cases transaction-long metadata locks
could be released before the transaction was committed. This could
happen when a active transaction was ended by a "START TRANSACTION"
or "BEGIN" statement, in which case the metadata locks would be
released before the actual commit of the active transaction.
The solution is to defer the release of metadata locks to after the
transaction has been implicitly committed. No test case is provided
as the effort to provide one is too disproportional to the size of
the fix.
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.
sql/mdl.cc:
Improve comments.
Add asserts to backup()/restore_from_backup()/merge() methods.
Fix an order bug in the error path of mdl_acquire_exclusive_locks():
we used to first free a ticket object, and only then exclude
it from the list of tickets.
----------------------------------------------------------
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).
mysql-test/r/mdl_sync.result:
Add test case result.
mysql-test/t/mdl_sync.test:
Add test case for shared lock upgrade case.
sql/event_db_repository.cc:
Rename mdl_alloc_lock to mdl_request_alloc.
sql/ha_ndbcluster_binlog.cc:
Use new function names to initialize MDL lock requests.
sql/lock.cc:
Rename MDL functions.
sql/log_event.cc:
The MDL request now holds the table and database name data (MDL_KEY).
sql/mdl.cc:
Move the MDL key to the MDL_LOCK structure in order to make the
object suitable for allocation from a fixed-size allocator. This
allows the simplification of the lists in the MDL_LOCK object,
which now are just two, one for granted tickets and other for
waiting (upgraders) tickets.
Recursive requests for a shared lock on the same object can now
be granted using the same lock ticket. This schema is only used
for shared locks because that the only case that matters. This
is used to avoid waste of resources in case a context (connection)
already holds a shared lock on a object.
sql/mdl.h:
Introduce a metadata lock object key which is used to uniquely
identify lock objects.
Separate the structure used to represent pending lock requests
from the structure used to represent granted metadata locks.
Rename functions used to manipulate locks requests in order to
have a more consistent function naming schema.
sql/sp_head.cc:
Rename mdl_alloc_lock to mdl_request_alloc.
sql/sql_acl.cc:
Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_base.cc:
Various changes to accommodate that lock requests are separated
from lock tickets (granted locks).
sql/sql_class.h:
Last acquired lock before the savepoint was set.
sql/sql_delete.cc:
Various changes to accommodate that lock requests are separated
from lock tickets (granted locks).
sql/sql_handler.cc:
Various changes to accommodate that lock requests are separated
from lock tickets (granted locks).
sql/sql_insert.cc:
Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_parse.cc:
Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_plist.h:
Typedef for iterator type.
sql/sql_plugin.cc:
Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_servers.cc:
Rename alloc_mdl_locks to alloc_mdl_requests.
sql/sql_show.cc:
Various changes to accommodate that lock requests are separated
from lock tickets (granted locks).
sql/sql_table.cc:
Various changes to accommodate that lock requests are separated
from lock tickets (granted locks).
sql/sql_trigger.cc:
Save reference to the lock ticket so it can be downgraded later.
sql/sql_udf.cc:
Rename alloc_mdl_locks to alloc_mdl_requests.
sql/table.cc:
Rename mdl_alloc_lock to mdl_request_alloc.
sql/table.h:
Separate MDL lock requests from lock tickets (granted locks).
storage/myisammrg/ha_myisammrg.cc:
Rename alloc_mdl_locks to alloc_mdl_requests.
------------------------------------------------------------
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: 2617.22.4
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: mysql-6.0-runtime
timestamp: Mon 2009-01-26 15:19:14 -0200
message:
Move checks for OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN to a separate
helper function.
sql/ha_ndbcluster.cc:
Use helper method to check transaction mode.
sql/log.cc:
Use helper method to check transaction mode.
sql/sql_cache.cc:
Use helper method to check transaction mode.
sql/sql_class.cc:
Use helper method to check transaction mode.
sql/sql_class.h:
Add helper method to check whether session is in a multi-statement
transaction.
sql/sql_parse.cc:
Use helper method to check transaction mode.
sql/transaction.cc:
Use helper method to check transaction mode.
------------------------------------------------------------
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.
client/Makefile.am:
Add new file to the build.
libmysqld/CMakeLists.txt:
Add new file to the build.
libmysqld/Makefile.am:
Add new file to the build.
sql/CMakeLists.txt:
Add new file to the build.
sql/Makefile.am:
Add new file to the build.
sql/handler.cc:
Remove multiplexer commit or rollback function. Most callers already
have enough information to decided whether to rollback or commit.
Having plain and well named functions makes it easier to read
and understand code.
sql/handler.h:
Remove wrapper function as the low level transaction functions
shouldn't be called directly anymore.
sql/log_event.cc:
Rename transaction management functions to the new names.
sql/log_event_old.cc:
Rename transaction management functions to the new names.
sql/mysql_priv.h:
Remove obsolete functions for implicit and explicit commit.
sql/rpl_injector.cc:
Rename transaction management functions to the new names.
sql/rpl_rli.cc:
Rename transaction management functions to the new names.
sql/set_var.cc:
Rename transaction management functions to the new names.
sql/slave.cc:
Rename transaction management functions to the new names.
sql/sql_base.cc:
Rename transaction management functions to the new names.
sql/sql_class.cc:
Rename transaction management functions to the new names.
sql/sql_delete.cc:
Rename transaction management functions to the new names.
sql/sql_do.cc:
Rename transaction management functions to the new names.
sql/sql_insert.cc:
Rename transaction management functions to the new names.
sql/sql_parse.cc:
Rename transaction management functions to the new names.
sql/sql_partition.cc:
Rename transaction management functions to the new names.
sql/sql_table.cc:
Rename transaction management functions to the new names.
sql/transaction.cc:
Implement wrapper functions to differentiate operations on
the single statement transaction from the ones operating
on the normal transaction.
sql/transaction.h:
Export new functions for dealing with transaction commands.
------------------------------------------------------------
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: 2630.13.16
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: WL#4284
timestamp: Sat 2008-07-26 13:38:20 -0300
message:
WL#4284: Transactional DDL locking
SQL statements' effect on transactions.
Currently the MySQL server and its storage engines are not
capable of rolling back operations that define or modify data
structures (also known as DDL statements) or operations that
alter any of the system tables (the mysql database). Allowing
these group of statements to participate in transactions
is unfeasible at this time (since rollback has no effect
whatsoever on them) and goes against the design of our metadata
locking subsystem.
The solution is to issue implicit commits before and after
those statements execution. This effectively confines each of
those statements to its own special transaction and ensures
that metadata locks taken during this special transaction
are not leaked into posterior statements/transactions.
mysql-test/include/commit.inc:
Alter table rename was not committing the normal transaction at the
end of its execution, and as a consequence, the commit was being
issued in the next DDL command (rename table) that happened to end
the active transaction. Other changes are to take into account the
implicit commits issued before and after the DDL command execution.
mysql-test/include/implicit_commit_helper.inc:
Add auxiliary test that shows if a statement issued a
implicit commit.
mysql-test/r/commit_1innodb.result:
Update test case result.
mysql-test/r/implicit_commit.result:
Test implicit commit behavior of some SQL commands.
mysql-test/t/implicit_commit.test:
Test implicit commit behavior of some SQL commands.
sql/events.cc:
Transaction is now ended before the command execution.
sql/mysql_priv.h:
Add flags array for server commands and remove historical
left over.
sql/sql_class.h:
Add flags to control when to issue implicit commits before and
after a command execution.
sql/sql_delete.cc:
A implicit commit is issued at the end of truncate
statements.
sql/sql_parse.cc:
Mark commands that need implicit commits before and
after their executions. The implicit commits of the
statement and the normal transaction are now issued
regardless of the user access privileges.
sql/sql_table.cc:
A implicit commit is now issued before admin commands.
tests/mysql_client_test.c:
Test that COM_REFRESH issues a implicit commit.
------------------------------------------------------------
revno: 2630.13.16
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: WL#4284
timestamp: Sat 2008-07-26 13:38:20 -0300
message:
WL#4284: Transactional DDL locking
SQL statements' effect on transactions.
Currently the MySQL server and its storage engines are not
capable of rolling back operations that define or modify data
structures (also known as DDL statements) or operations that
alter any of the system tables (the mysql database). Allowing
these group of statements to participate in transactions
is unfeasible at this time (since rollback has no effect
whatsoever on them) and goes against the design of our metadata
locking subsystem.
The solution is to issue implicit commits before and after
those statements execution. This effectively confines each of
those statements to its own special transaction and ensures
that metadata locks taken during this special transaction
are not leaked into posterior statements/transactions.
----------------------------------------------------------
revno: 2630.2.23
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-runtime
timestamp: Fri 2008-06-27 21:15:11 +0400
message:
Add an assert that we never call COMMIT or ROLLBACK while having
a table lock.
sql/sql_parse.cc:
We should never call COMMIT or ROLLBACK with a table lock, except
when under LOCK TABLES.
----------------------------------------------------------
revno: 2630.2.23
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-runtime
timestamp: Fri 2008-06-27 21:15:11 +0400
message:
Add an assert that we never call COMMIT or ROLLBACK while having
a table lock.
Support for flushing individual logs, so that the user can
selectively flush a subset of the server logs.
Flush of individual logs is done according to the
following syntax:
FLUSH <log_category> LOGS;
The syntax is extended so that the user is able to flush a
subset of logs:
FLUSH [log_category LOGS,];
where log_category is one of:
SLOW
ERROR
BINARY
ENGINE
GENERAL
RELAY.
mysql-test/suite/rpl/r/rpl_flush_logs.result:
Test result for WL#5142.
mysql-test/suite/rpl/t/rpl_flush_logs.test:
Added the test file to verify if the 'flush individual log'
statement works fine.
sql/log.cc:
Added the two functions to flush slow and general log.
sql/sql_parse.cc:
Added code to flush specified logs against the option.
sql/sql_yacc.yy:
Added code to parse the 'flush * log' statement syntax and
set its option to Lex->type.
Support for flushing individual logs, so that the user can
selectively flush a subset of the server logs.
Flush of individual logs is done according to the
following syntax:
FLUSH <log_category> LOGS;
The syntax is extended so that the user is able to flush a
subset of logs:
FLUSH [log_category LOGS,];
where log_category is one of:
SLOW
ERROR
BINARY
ENGINE
GENERAL
RELAY.
