Bug#54678: InnoDB, TRUNCATE, ALTER, I_S SELECT, crash or deadlock
- Incompatible change: truncate no longer resorts to a row by
row delete if the storage engine does not support the truncate
method. Consequently, the count of affected rows does not, in
any case, reflect the actual number of rows.
- Incompatible change: it is no longer possible to truncate a
table that participates as a parent in a foreign key constraint,
unless it is a self-referencing constraint (both parent and child
are in the same table). To work around this incompatible change
and still be able to truncate such tables, disable foreign checks
with SET foreign_key_checks=0 before truncate. Alternatively, if
foreign key checks are necessary, please use a DELETE statement
without a WHERE condition.
Problem description:
The problem was that for storage engines that do not support
truncate table via a external drop and recreate, such as InnoDB
which implements truncate via a internal drop and recreate, the
delete_all_rows method could be invoked with a shared metadata
lock, causing problems if the engine needed exclusive access
to some internal metadata. This problem originated with the
fact that there is no truncate specific handler method, which
ended up leading to a abuse of the delete_all_rows method that
is primarily used for delete operations without a condition.
Solution:
The solution is to introduce a truncate handler method that is
invoked when the engine does not support truncation via a table
drop and recreate. This method is invoked under a exclusive
metadata lock, so that there is only a single instance of the
table when the method is invoked.
Also, the method is not invoked and a error is thrown if
the table is a parent in a non-self-referencing foreign key
relationship. This was necessary to avoid inconsistency as
some integrity checks are bypassed. This is inline with the
fact that truncate is primarily a DDL operation that was
designed to quickly remove all data from a table.
mysql-test/suite/innodb/t/innodb-truncate.test:
Add test cases for truncate and foreign key checks.
Also test that InnoDB resets auto-increment on truncate.
mysql-test/suite/innodb/t/innodb.test:
FK is not necessary, test is related to auto-increment.
Update error number, truncate is no longer invoked if
table is parent in a FK relationship.
mysql-test/suite/innodb/t/innodb_mysql.test:
Update error number, truncate is no longer invoked if
table is parent in a FK relationship.
Use delete instead of truncate, test is used to check
the interaction of FKs, triggers and delete.
mysql-test/suite/parts/inc/partition_check.inc:
Fix typo.
mysql-test/suite/sys_vars/t/foreign_key_checks_func.test:
Update error number, truncate is no longer invoked if
table is parent in a FK relationship.
mysql-test/t/mdl_sync.test:
Modify test case to reflect and ensure that truncate takes
a exclusive metadata lock.
mysql-test/t/trigger-trans.test:
Update error number, truncate is no longer invoked if
table is parent in a FK relationship.
sql/ha_partition.cc:
Reorganize the various truncate methods. delete_all_rows is now
passed directly to the underlying engines, so as truncate. The
code responsible for truncating individual partitions is moved
to ha_partition::truncate_partition, which is invoked when a
ALTER TABLE t1 TRUNCATE PARTITION p statement is executed.
Since the partition truncate no longer can be invoked via
delete, the bitmap operations are not necessary anymore. The
explicit reset of the auto-increment value is also removed
as the underlying engines are now responsible for reseting
the value.
sql/handler.cc:
Wire up the handler truncate method.
sql/handler.h:
Introduce and document the truncate handler method. It assumes
certain use cases of delete_all_rows.
Add method to retrieve the list of foreign keys referencing a
table. Method is used to avoid truncating tables that are
parent in a foreign key relationship.
sql/share/errmsg-utf8.txt:
Add error message for truncate and FK.
sql/sql_lex.h:
Introduce a flag so that the partition engine can detect when
a partition is being truncated. Used to give a special error.
sql/sql_parse.cc:
Function mysql_truncate_table no longer exists.
sql/sql_partition_admin.cc:
Implement the TRUNCATE PARTITION statement.
sql/sql_truncate.cc:
Change the truncate table implementation to use the new truncate
handler method and to not rely on row-by-row delete anymore.
The truncate handler method is always invoked with a exclusive
metadata lock. Also, it is no longer possible to truncate a
table that is parent in some non-self-referencing foreign key.
storage/archive/ha_archive.cc:
Rename method as the description indicates that in the future
this could be a truncate operation.
storage/blackhole/ha_blackhole.cc:
Implement truncate as no operation for the blackhole engine in
order to remain compatible with older releases.
storage/federated/ha_federated.cc:
Introduce truncate method that invokes delete_all_rows.
This is required to support partition truncate as this
form of truncate does not implement the drop and recreate
protocol.
storage/heap/ha_heap.cc:
Introduce truncate method that invokes delete_all_rows.
This is required to support partition truncate as this
form of truncate does not implement the drop and recreate
protocol.
storage/ibmdb2i/ha_ibmdb2i.cc:
Introduce truncate method that invokes delete_all_rows.
This is required to support partition truncate as this
form of truncate does not implement the drop and recreate
protocol.
storage/innobase/handler/ha_innodb.cc:
Rename delete_all_rows to truncate. InnoDB now does truncate
under a exclusive metadata lock.
Introduce and reorganize methods used to retrieve the list
of foreign keys referenced by a or referencing a table.
storage/myisammrg/ha_myisammrg.cc:
Introduce truncate method that invokes delete_all_rows.
This is required in order to remain compatible with earlier
releases where truncate would resort to a row-by-row delete.
Bug#54678: InnoDB, TRUNCATE, ALTER, I_S SELECT, crash or deadlock
- Incompatible change: truncate no longer resorts to a row by
row delete if the storage engine does not support the truncate
method. Consequently, the count of affected rows does not, in
any case, reflect the actual number of rows.
- Incompatible change: it is no longer possible to truncate a
table that participates as a parent in a foreign key constraint,
unless it is a self-referencing constraint (both parent and child
are in the same table). To work around this incompatible change
and still be able to truncate such tables, disable foreign checks
with SET foreign_key_checks=0 before truncate. Alternatively, if
foreign key checks are necessary, please use a DELETE statement
without a WHERE condition.
Problem description:
The problem was that for storage engines that do not support
truncate table via a external drop and recreate, such as InnoDB
which implements truncate via a internal drop and recreate, the
delete_all_rows method could be invoked with a shared metadata
lock, causing problems if the engine needed exclusive access
to some internal metadata. This problem originated with the
fact that there is no truncate specific handler method, which
ended up leading to a abuse of the delete_all_rows method that
is primarily used for delete operations without a condition.
Solution:
The solution is to introduce a truncate handler method that is
invoked when the engine does not support truncation via a table
drop and recreate. This method is invoked under a exclusive
metadata lock, so that there is only a single instance of the
table when the method is invoked.
Also, the method is not invoked and a error is thrown if
the table is a parent in a non-self-referencing foreign key
relationship. This was necessary to avoid inconsistency as
some integrity checks are bypassed. This is inline with the
fact that truncate is primarily a DDL operation that was
designed to quickly remove all data from a table.
for ALTER TABLE + MERGE tables
The patch for Bug#56292 changed how metadata locks are taken for MERGE
tables. After the patch, locking the MERGE table will also lock the
children tables with the same metadata lock type. This means that
LOCK TABLES on a MERGE table also will implicitly do LOCK TABLES on
the children tables.
A consequence of this change, is that it is possible to do LOCK TABLES
on a child table both explicitly and implicitly with the same statement
and that these two locks can be of different strength. For example,
LOCK TABLES child READ, merge WRITE.
In LOCK TABLES mode, we are not allowed to take new locks and each
statement must therefore try to find an existing TABLE instance with
a suitable lock. The code that searched for a suitable TABLE instance,
only considered table level locks. If a child table was locked twice,
it was therefore possible for this code to find a TABLE instance with
suitable table level locks but without suitable metadata lock.
This problem caused the assert in upgrade_shared_lock_to_exclusive()
to be triggered as it tried to upgrade a MDL_SHARED lock to
EXCLUSIVE. The problem was a regression caused by the patch for
Bug#56292.
This patch fixes the problem by partially reverting the changes
done by Bug#56292. Now, the children tables will only use the
same metadata lock as the MERGE table for MDL_SHARED_NO_WRITE
when not in locked tables mode. This means that LOCK TABLE
on a MERGE table will not implicitly lock the children tables.
This still fixes the original problem in Bug#56292 without
causing a regression.
Test case added to merge.test.
for ALTER TABLE + MERGE tables
The patch for Bug#56292 changed how metadata locks are taken for MERGE
tables. After the patch, locking the MERGE table will also lock the
children tables with the same metadata lock type. This means that
LOCK TABLES on a MERGE table also will implicitly do LOCK TABLES on
the children tables.
A consequence of this change, is that it is possible to do LOCK TABLES
on a child table both explicitly and implicitly with the same statement
and that these two locks can be of different strength. For example,
LOCK TABLES child READ, merge WRITE.
In LOCK TABLES mode, we are not allowed to take new locks and each
statement must therefore try to find an existing TABLE instance with
a suitable lock. The code that searched for a suitable TABLE instance,
only considered table level locks. If a child table was locked twice,
it was therefore possible for this code to find a TABLE instance with
suitable table level locks but without suitable metadata lock.
This problem caused the assert in upgrade_shared_lock_to_exclusive()
to be triggered as it tried to upgrade a MDL_SHARED lock to
EXCLUSIVE. The problem was a regression caused by the patch for
Bug#56292.
This patch fixes the problem by partially reverting the changes
done by Bug#56292. Now, the children tables will only use the
same metadata lock as the MERGE table for MDL_SHARED_NO_WRITE
when not in locked tables mode. This means that LOCK TABLE
on a MERGE table will not implicitly lock the children tables.
This still fixes the original problem in Bug#56292 without
causing a regression.
Test case added to merge.test.
ALTER TABLE on a MERGE table could cause a deadlock with two
other connections if we reached a situation where:
1) A connection doing ALTER TABLE can't upgrade to MDL_EXCLUSIVE on the
parent table, but holds TL_READ_NO_INSERT on the child tables.
2) A connection doing DELETE on a child table can't get TL_WRITE on it
since ALTER TABLE holds TL_READ_NO_INSERT.
3) A connection doing SELECT on the parent table can't get TL_READ on
the child tables since TL_WRITE is ahead in the lock queue, but holds
MDL_SHARED_READ on the parent table preventing ALTER TABLE from upgrading.
For regular tables, this deadlock is avoided by having ALTER TABLE
take a MDL_SHARED_NO_WRITE metadata lock on the table. This prevents
DELETE from acquiring MDL_SHARED_WRITE on the table before ALTER TABLE
tries to upgrade to MDL_EXCLUSIVE. In the example above, SELECT would
therefore not be blocked by the pending DELETE as DELETE would not be
able to enter TL_WRITE in the table lock queue.
This patch fixes the problem for merge tables by using the same metadata
lock type for child tables as for the parent table. The child tables will
in this case therefore be locked with MDL_SHARED_NO_WRITE, preventing
DELETE from acquiring a metadata lock and enter into the table lock queue.
Change in behavior: By taking the same metadata lock for child tables
as for the parent table, LOCK TABLE on the parent table will now also
implicitly lock the child tables. Since LOCK TABLE on the parent table
now takes more than one metadata lock, it is possible for LOCK TABLE
... WRITE on the parent table or child tables to give ER_LOCK_DEADLOCK
error.
Test case added to mdl_sync.test.
Merge.test/.result has been updated to reflect the change to LOCK TABLE.
ALTER TABLE on a MERGE table could cause a deadlock with two
other connections if we reached a situation where:
1) A connection doing ALTER TABLE can't upgrade to MDL_EXCLUSIVE on the
parent table, but holds TL_READ_NO_INSERT on the child tables.
2) A connection doing DELETE on a child table can't get TL_WRITE on it
since ALTER TABLE holds TL_READ_NO_INSERT.
3) A connection doing SELECT on the parent table can't get TL_READ on
the child tables since TL_WRITE is ahead in the lock queue, but holds
MDL_SHARED_READ on the parent table preventing ALTER TABLE from upgrading.
For regular tables, this deadlock is avoided by having ALTER TABLE
take a MDL_SHARED_NO_WRITE metadata lock on the table. This prevents
DELETE from acquiring MDL_SHARED_WRITE on the table before ALTER TABLE
tries to upgrade to MDL_EXCLUSIVE. In the example above, SELECT would
therefore not be blocked by the pending DELETE as DELETE would not be
able to enter TL_WRITE in the table lock queue.
This patch fixes the problem for merge tables by using the same metadata
lock type for child tables as for the parent table. The child tables will
in this case therefore be locked with MDL_SHARED_NO_WRITE, preventing
DELETE from acquiring a metadata lock and enter into the table lock queue.
Change in behavior: By taking the same metadata lock for child tables
as for the parent table, LOCK TABLE on the parent table will now also
implicitly lock the child tables. Since LOCK TABLE on the parent table
now takes more than one metadata lock, it is possible for LOCK TABLE
... WRITE on the parent table or child tables to give ER_LOCK_DEADLOCK
error.
Test case added to mdl_sync.test.
Merge.test/.result has been updated to reflect the change to LOCK TABLE.
- Changed to still use bcmp() in certain cases becasue
- Faster for short unaligneed strings than memcmp()
- Bettern when using valgrind
- Changed to use my_sprintf() instead of sprintf() to get higher portability for old systems
- Changed code to use MariaDB version of select->skip_record()
- Removed -%::SCCS/s.% from Makefile.am:s to remove automake warnings
Fix warnings flagged by the new warning option -Wunused-but-set-variable
that was added to GCC 4.6 and that is enabled by -Wunused and -Wall. The
option causes a warning whenever a local variable is assigned to but is
later unused. It also warns about meaningless pointer dereferences.
client/mysql.cc:
Meaningless pointer dereferences.
client/mysql_upgrade.c:
Check whether reading from the file succeeded.
extra/comp_err.c:
Unused.
extra/yassl/src/yassl_imp.cpp:
Skip instead of reading data that is discarded.
include/my_pthread.h:
Variable is only used in debug builds.
include/mysys_err.h:
Add new error messages.
mysys/errors.c:
Add new error message for permission related functions.
mysys/mf_iocache.c:
Variable is only checked under THREAD.
mysys/my_copy.c:
Raise a error if chmod or chown fails.
mysys/my_redel.c:
Raise a error if chmod or chown fails.
regex/engine.c:
Use a equivalent variable for the assert.
server-tools/instance-manager/instance_options.cc:
Unused.
sql/field.cc:
Unused.
sql/item.cc:
Unused.
sql/log.cc:
Do not ignore the return value of freopen: only set buffer if
reopening succeeds.
Adjust doxygen comment to the right function.
Pass message lenght to log function.
sql/mysqld.cc:
Do not ignore the return value of freopen: only set buffer if
reopening succeeds.
sql/partition_info.cc:
Unused.
sql/slave.cc:
No need to set pointer to the address of '\0'.
sql/spatial.cc:
Unused. Left for historical purposes.
sql/sql_acl.cc:
Unused.
sql/sql_base.cc:
Pointers are always set to the same variables.
sql/sql_parse.cc:
End statement if reading fails.
Store the buffer after it has actually been updated.
sql/sql_repl.cc:
No need to set pointer to the address of '\0'.
sql/sql_show.cc:
Put variable under the same ifdef block.
sql/udf_example.c:
Set null pointer flag appropriately.
storage/csv/ha_tina.cc:
Meaningless dereferences.
storage/example/ha_example.cc:
Return the error since it's available.
storage/myisam/mi_locking.c:
Remove unused and dead code.
Fix warnings flagged by the new warning option -Wunused-but-set-variable
that was added to GCC 4.6 and that is enabled by -Wunused and -Wall. The
option causes a warning whenever a local variable is assigned to but is
later unused. It also warns about meaningless pointer dereferences.
Fixed compiler warnings.
queues.h and queues.c are now based on the UNIREG code and thus made BSD.
Fix code to use new queue() interface. This mostly affects how you access elements in the queue.
If USE_NET_CLEAR is not set, don't clear connection from unexpected characters. This should give a speed up when doing a lot of fast queries.
Fixed some code in ma_ft_boolean_search.c that had not made it from myisam/ft_boolean_search.c
include/queues.h:
Use UNIREG code base (BSD)
Changed init_queue() to take all initialization arguments.
New interface to access elements in queue
include/thr_alarm.h:
Changed to use time_t instead of ulong (portability)
Added index_in_queue, to be able to remove random element from queue in O(1)
mysys/queues.c:
Use UNIREG code base (BSD)
init_queue() and reinit_queue() now takes more initialization arguments. (No need for init_queue_ex() anymore)
Now one can tell queue_insert() to store in the element a pointer to where element is in queue. This allows one to remove elements from queue in O(1) instead of O(N)
mysys/thr_alarm.c:
Use new option in queue() to allow fast removal of elements.
Do less inside LOCK_alarm mutex.
This should give a major speed up of thr_alarm usage when there is many threads
sql/create_options.cc:
Fixed wrong printf
sql/event_queue.cc:
Use new queue interface()
sql/filesort.cc:
Use new queue interface()
sql/ha_partition.cc:
Use new queue interface()
sql/ha_partition.h:
Fixed compiler warning
sql/item_cmpfunc.cc:
Fixed compiler warning
sql/item_subselect.cc:
Use new queue interface()
Removed not used variable
sql/net_serv.cc:
If USE_NET_CLEAR is not set, don't clear connection from unexpected characters.
This should give a speed up when doing a lot of fast queries at the disadvantage that if there is a bug in the client protocol the connection will be dropped instead of being unnoticed.
sql/opt_range.cc:
Use new queue interface()
Fixed compiler warnings
sql/uniques.cc:
Use new queue interface()
storage/maria/ma_ft_boolean_search.c:
Copy code from myisam/ft_boolean_search.c
Use new queue interface()
storage/maria/ma_ft_nlq_search.c:
Use new queue interface()
storage/maria/ma_sort.c:
Use new queue interface()
storage/maria/maria_pack.c:
Use new queue interface()
Use queue_fix() instead of own loop to fix queue.
storage/myisam/ft_boolean_search.c:
Use new queue interface()
storage/myisam/ft_nlq_search.c:
Use new queue interface()
storage/myisam/mi_test_all.sh:
Remove temporary file from last run
storage/myisam/myisampack.c:
Use new queue interface()
Use queue_fix() instead of own loop to fix queue.
storage/myisam/sort.c:
Use new queue interface()
storage/myisammrg/myrg_queue.c:
Use new queue interface()
storage/myisammrg/myrg_rnext.c:
Use new queue interface()
storage/myisammrg/myrg_rnext_same.c:
Use new queue interface()
storage/myisammrg/myrg_rprev.c:
Use new queue interface()
Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
client/mysqldump.c:
Pass my_free directly as its signature is compatible with the
callback type -- which wasn't the case for free_table_ent.
Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
Apart strict-aliasing warnings, fix the remaining warnings
generated by GCC 4.4.4 -Wall and -Wextra flags.
One major source of warnings was the in-house function my_bcmp
which (unconventionally) took pointers to unsigned characters
as the byte sequences to be compared. Since my_bcmp and bcmp
are deprecated functions whose only difference with memcmp is
the return value, every use of the function is replaced with
memcmp as the special return value wasn't actually being used
by any caller.
There were also various other warnings, mostly due to type
mismatches, missing return values, missing prototypes, dead
code (unreachable) and ignored return values.
BUILD/SETUP.sh:
Remove flags that are implied by -Wall and -Wextra.
Do not warn about unused parameters in C++.
BUILD/check-cpu:
Print only the compiler version instead of verbose banner.
Although the option is gcc specific, the check was only
being used for GCC specific checks anyway.
client/mysql.cc:
bcmp is no longer defined.
client/mysqltest.cc:
Pass a string to function expecting a format string.
Replace use of bcmp with memcmp.
cmd-line-utils/readline/Makefile.am:
Always define _GNU_SOURCE when compiling GNU readline.
Required to make certain prototypes visible.
cmd-line-utils/readline/input.c:
Condition for the code to be meaningful.
configure.in:
Remove check for bcmp.
extra/comp_err.c:
Use appropriate type.
extra/replace.c:
Replace use of bcmp with memcmp.
extra/yassl/src/crypto_wrapper.cpp:
Do not ignore the return value of fgets. Retrieve the file
position if fgets succeed -- if it fails, the function will
bail out and return a error.
extra/yassl/taocrypt/include/blowfish.hpp:
Use a single array instead of accessing positions of the sbox_
through a subscript to pbox_.
extra/yassl/taocrypt/include/runtime.hpp:
One definition of such functions is enough.
extra/yassl/taocrypt/src/aes.cpp:
Avoid potentially ambiguous conditions.
extra/yassl/taocrypt/src/algebra.cpp:
Rename arguments to avoid shadowing related warnings.
extra/yassl/taocrypt/src/blowfish.cpp:
Avoid potentially ambiguous conditions.
extra/yassl/taocrypt/src/integer.cpp:
Do not define type within a anonymous union.
Use a variable to return a value instead of
leaving the result in a register -- compiler
does not know the logic inside the asm.
extra/yassl/taocrypt/src/misc.cpp:
Define handler for pure virtual functions.
Remove unused code.
extra/yassl/taocrypt/src/twofish.cpp:
Avoid potentially ambiguous conditions.
extra/yassl/testsuite/test.hpp:
Function must have C language linkage.
include/m_string.h:
Remove check which relied on bcmp being defined -- they weren't
being used as bcmp is only visible when _BSD_SOURCE is defined.
include/my_bitmap.h:
Remove bogus helpers which were used only in a few files and
were causing warnings about dead code.
include/my_global.h:
Due to G++ bug, always silence false-positive uninitialized
variables warnings when compiling C++ code with G++.
Remove bogus helper.
libmysql/Makefile.shared:
Remove built-in implementation of bcmp.
mysql-test/lib/My/SafeProcess/safe_process.cc:
Cast pid to largest possible type for a process identifier.
mysys/mf_loadpath.c:
Leave space of the ending nul.
mysys/mf_pack.c:
Replace bcmp with memcmp.
mysys/my_bitmap.c:
Dead code removal.
mysys/my_gethwaddr.c:
Remove unused variable.
mysys/my_getopt.c:
Silence bogus uninitialized variable warning.
Do not cast away the constant qualifier.
mysys/safemalloc.c:
Cast to expected type.
mysys/thr_lock.c:
Silence bogus uninitialized variable warning.
sql/field.cc:
Replace bogus helper with a more appropriate logic which is
used throughout the code.
sql/item.cc:
Remove bogus logical condition which always evaluates to TRUE.
sql/item_create.cc:
Simplify code to avoid signedness related warnings.
sql/log_event.cc:
Replace use of bcmp with memcmp.
No need to use helpers for simple bit operations.
sql/log_event_old.cc:
Replace bmove_align with memcpy.
sql/mysqld.cc:
Move use declaration of variable to the ifdef block where it
is used. Remove now-unnecessary casts and arguments.
sql/set_var.cc:
Replace bogus helpers with simple and classic bit operations.
sql/slave.cc:
Cast to expected type and silence bogus warning.
sql/sql_class.h:
Don't use enum values as bit flags, the supposed type safety is
bogus as the combined bit flags are not a value in the enumeration.
sql/udf_example.c:
Only declare variable when necessary.
sql/unireg.h:
Replace use of bmove_align with memcpy.
storage/innobase/os/os0file.c:
Silence bogus warning.
storage/myisam/mi_open.c:
Remove bogus cast, DBUG_DUMP expects a pointer to unsigned
char.
storage/myisam/mi_page.c:
Remove bogus cast, DBUG_DUMP expects a pointer to unsigned
char.
strings/bcmp.c:
Remove built-in bcmp.
strings/ctype-ucs2.c:
Silence bogus warning.
tests/mysql_client_test.c:
Use a appropriate type as expected by simple_command().
Apart strict-aliasing warnings, fix the remaining warnings
generated by GCC 4.4.4 -Wall and -Wextra flags.
One major source of warnings was the in-house function my_bcmp
which (unconventionally) took pointers to unsigned characters
as the byte sequences to be compared. Since my_bcmp and bcmp
are deprecated functions whose only difference with memcmp is
the return value, every use of the function is replaced with
memcmp as the special return value wasn't actually being used
by any caller.
There were also various other warnings, mostly due to type
mismatches, missing return values, missing prototypes, dead
code (unreachable) and ignored return values.
MERGE engine".
Backport the patch from 6.0 by Ingo Struewing:
revid:ingo.struewing@sun.com-20091028183659-6kmv1k3gdq6cpg4d
Bug#36171 - CREATE TEMPORARY TABLE and MERGE engine
In former MySQL versions, up to 5.1.23/6.0.4 it was possible to create
temporary MERGE tables with non-temporary MyISAM tables.
This has been changed in the mentioned version due to Bug 19627
(temporary merge table locking). MERGE children were locked through
the parent table. If the parent was temporary, it was not locked and
so the children were not locked either. Parallel use of the MyISAM
tables corrupted them.
Since 6.0.6 (WL 4144 - Lock MERGE engine children), the children are
locked independently from the parent. Now it is possible to allow
non-temporary children with a temporary parent. Even though the
temporary MERGE table itself is not locked, each non-temporary
MyISAM table is locked anyway.
NOTE: Behavior change: In 5.1.23/6.0.4 we prohibited non-temporary
children with a temporary MERGE table. Now we re-allow it.
An important side-effect is that temporary tables, which overlay
non-temporary MERGE children, overlay the children in the MERGE table.
mysql-test/r/merge.result:
Update results (Bug#36171).
mysql-test/r/merge_mmap.result:
Update results (Bug#36171).
mysql-test/t/merge.test:
Add tests for Bug#36171
mysql-test/t/merge_mmap.test:
Add tests for Bug#36171.
storage/myisammrg/ha_myisammrg.cc:
Changed constraint for temporary state of tables.
MERGE engine".
Backport the patch from 6.0 by Ingo Struewing:
revid:ingo.struewing@sun.com-20091028183659-6kmv1k3gdq6cpg4d
Bug#36171 - CREATE TEMPORARY TABLE and MERGE engine
In former MySQL versions, up to 5.1.23/6.0.4 it was possible to create
temporary MERGE tables with non-temporary MyISAM tables.
This has been changed in the mentioned version due to Bug 19627
(temporary merge table locking). MERGE children were locked through
the parent table. If the parent was temporary, it was not locked and
so the children were not locked either. Parallel use of the MyISAM
tables corrupted them.
Since 6.0.6 (WL 4144 - Lock MERGE engine children), the children are
locked independently from the parent. Now it is possible to allow
non-temporary children with a temporary parent. Even though the
temporary MERGE table itself is not locked, each non-temporary
MyISAM table is locked anyway.
NOTE: Behavior change: In 5.1.23/6.0.4 we prohibited non-temporary
children with a temporary MERGE table. Now we re-allow it.
An important side-effect is that temporary tables, which overlay
non-temporary MERGE children, overlay the children in the MERGE table.
and a backport of relevant changes from the 6.0
version of the fix done by Ingo Struewing.
The bug itself was fixed by the patch for Bug#54811.
MyISAMMRG engine would try to use MMAP on its children
even on platforms that don't support it and even if
myisam_use_mmap option was off.
This lead to an infinite hang in INSERT ... SELECT into
a MyISAMMRG table when the destination MyISAM table
was also selected from.
A bug in duplicate detection fixed by 54811 was essential to
the hang - when a duplicate is detected, the optimizer
disables the use of memory mapped files, and it wasn't the case.
The patch below is also to not turn on MMAP on children tables
if myisam_use_mmap is off.
A test case is added to cover MyISAMMRG and myisam_use_mmap
option.
mysql-test/r/merge_mmap.result:
Result file - Bug#50788.
mysql-test/t/merge_mmap-master.opt:
An option file for the test for Bug#50788 -- use mmap.
mysql-test/t/merge_mmap.test:
Try INSERT ... SELECT into a merge table when myisam_use_mmap is on (Bug#50788).
storage/myisam/mi_statrec.c:
Fixed misinterpretation of the return value of my_b_read().
storage/myisammrg/ha_myisammrg.cc:
Skip HA_EXTRA_MMAP if MyISAM memory mapping is disabled.
and a backport of relevant changes from the 6.0
version of the fix done by Ingo Struewing.
The bug itself was fixed by the patch for Bug#54811.
MyISAMMRG engine would try to use MMAP on its children
even on platforms that don't support it and even if
myisam_use_mmap option was off.
This lead to an infinite hang in INSERT ... SELECT into
a MyISAMMRG table when the destination MyISAM table
was also selected from.
A bug in duplicate detection fixed by 54811 was essential to
the hang - when a duplicate is detected, the optimizer
disables the use of memory mapped files, and it wasn't the case.
The patch below is also to not turn on MMAP on children tables
if myisam_use_mmap is off.
A test case is added to cover MyISAMMRG and myisam_use_mmap
option.
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
The server crashed on an attempt to optimize a MERGE table with
non-existent child table.
mysql_admin_table() relied on the table to be successfully open
if a table object had been allocated.
Changed code to check return value of the open function before
calling a handler:: function on it.
mysql-test/r/merge.result:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
Updated result file.
mysql-test/t/merge.test:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
Changed tests to respect changed TEMPORARY MERGE locking (unrelated).
Changed tests to respect changed CREATE TABLE ... LIKE (unrelated).
Changed tests to respect that no new tables can be created
under LOCK TABLE (unrelated).
Added test for Bug#47633.
Changed error numbers to symbolic names.
Added test for child locking for ALTER under LOCK TABLE.
Since Bug 36171 is not pushed yet, not the whole patch has been backported.
mysys/my_delete.c:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
Fixed error reporting.
Fixed indentation.
mysys/my_mmap.c:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
Added DBUG.
sql/item_func.cc:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Added Debug Sync point, required by merge_sync.test.
sql/sql_table.cc:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
Do not call handler:: functions if the table was not opened
successfully.
Added Debug Sync point, required by merge_sync.test.
storage/myisam/mi_check.c:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
Unmap memory before exchanging data files. Needed on Windows.
storage/myisammrg/ha_myisammrg.cc:
Backport of revid:ingo.struewing@sun.com-20091223200354-r2uzbdkj2v6yv111
Added Debug Sync point, required by merge_sync.test.
merge_sync.test will be introduced by a patch for Bug 36171,
which is not pushed yet.
Bug#47633 - assert in ha_myisammrg::info during OPTIMIZE
The server crashed on an attempt to optimize a MERGE table with
non-existent child table.
mysql_admin_table() relied on the table to be successfully open
if a table object had been allocated.
Changed code to check return value of the open function before
calling a handler:: function on it.
strict aliasing violations.
One somewhat major source of strict-aliasing violations and
related warnings is the SQL_LIST structure. For example,
consider its member function `link_in_list` which takes
a pointer to pointer of type T (any type) as a pointer to
pointer to unsigned char. Dereferencing this pointer, which
is done to reset the next field, violates strict-aliasing
rules and might cause problems for surrounding code that
uses the next field of the object being added to the list.
The solution is to use templates to parametrize the SQL_LIST
structure in order to deference the pointers with compatible
types. As a side bonus, it becomes possible to remove quite
a few casts related to acessing data members of SQL_LIST.
sql/handler.h:
Use the appropriate template type argument.
sql/item.cc:
Remove now-unnecessary cast.
sql/item_subselect.cc:
Remove now-unnecessary casts.
sql/item_sum.cc:
Use the appropriate template type argument.
Remove now-unnecessary cast.
sql/mysql_priv.h:
Move SQL_LIST structure to sql_list.h
Use the appropriate template type argument.
sql/sp.cc:
Remove now-unnecessary casts.
sql/sql_delete.cc:
Use the appropriate template type argument.
Remove now-unnecessary casts.
sql/sql_derived.cc:
Remove now-unnecessary casts.
sql/sql_lex.cc:
Remove now-unnecessary casts.
sql/sql_lex.h:
SQL_LIST now takes a template type argument which must
match the type of the elements of the list. Use forward
declaration when the type is not available, it is used
in pointers anyway.
sql/sql_list.h:
Rename SQL_LIST to SQL_I_List. The template parameter is
the type of object that is stored in the list.
sql/sql_olap.cc:
Remove now-unnecessary casts.
sql/sql_parse.cc:
Remove now-unnecessary casts.
sql/sql_prepare.cc:
Remove now-unnecessary casts.
sql/sql_select.cc:
Remove now-unnecessary casts.
sql/sql_show.cc:
Remove now-unnecessary casts.
sql/sql_table.cc:
Remove now-unnecessary casts.
sql/sql_trigger.cc:
Remove now-unnecessary casts.
sql/sql_union.cc:
Remove now-unnecessary casts.
sql/sql_update.cc:
Remove now-unnecessary casts.
sql/sql_view.cc:
Remove now-unnecessary casts.
sql/sql_yacc.yy:
Remove now-unnecessary casts.
storage/myisammrg/ha_myisammrg.cc:
Remove now-unnecessary casts.
strict aliasing violations.
One somewhat major source of strict-aliasing violations and
related warnings is the SQL_LIST structure. For example,
consider its member function `link_in_list` which takes
a pointer to pointer of type T (any type) as a pointer to
pointer to unsigned char. Dereferencing this pointer, which
is done to reset the next field, violates strict-aliasing
rules and might cause problems for surrounding code that
uses the next field of the object being added to the list.
The solution is to use templates to parametrize the SQL_LIST
structure in order to deference the pointers with compatible
types. As a side bonus, it becomes possible to remove quite
a few casts related to acessing data members of SQL_LIST.
