SUPER_ACL should be checked unconditionally while verifying if the binlog_format
or the binlog_direct_non_transactional_updates might be changed.
Roughly speaking, both session values cannot be changed in the context of a
transaction or a stored function. Note that changing the global value does
not cause any effect until a new connection is created.
So, we fixed the problem by first checking the permissions and right after further
verifications are ignored if the global value is being updated. In this patch, we
also re-structure the test case to make it more readable.
The task is to
(a) add a comment on indexes and
(b) increase the maximum length of column, table and the new index comments.
The patch committed on behalf of Yoshinori Matsunobu (Yoshinori.Matsunobu@Sun.COM).
1. Now test use fake_relay_log primitive
2. Added RESET SLAVE to include/setup_fake_relay_log.inc for removing relay log info file
3. Added RESET SLAVE to include/cleanup_fake_relay_log.inc
4. Test moved to rpl suite as rpl_binlog_auto_inc_bug33029.test
5. Updated result file
As part of BUG@39934 fix, the public:
- THD::current_stmt_binlog_row_based
variable had been removed and replaced by a private variable:
- THD::current_stmt_binlog_format.
THD was refactored and some modifiers and accessors were
implemented for the new variable.
However, due to a bad merge, the
THD::current_stmt_binlog_row_based variable is back as a public
member of THD. This in itself is already potentially
harmful. What's even worse is that while merging some more
patches and resolving conflicts, the variable started being used
again, which is obviously wrong.
To fix this we:
1. remove the extraneous variable from sql_class.h
2. revert a bad merge for BUG#49132
3. merge BUG#49132 properly again (actually, making use of the
cset used to merge the original patch to mysql-pe).
mysql-test/t/disabled.def:
Restore disabled ssl tests: SSL certificates were updated.
Disable sp_sync.test, the test case can't work in next-4284.
mysql-test/t/partition_innodb.test:
Disable parsing of the test case for Bug#47343,
the test can not work in next-4284.
mysql-test/t/ps_ddl.test:
Update results (CREATE TABLE IF NOT EXISTS takes
into account existence of the temporary table).
Cherry-pick a fix Bug#37148 from next-mr, to preserve
file ids of the added files, and ensure that all the necessary
changes have been pulled.
Since initially Bug#37148 was null-merged into 6.0,
the changeset that is now being cherry-picked was likewise
null merged into next-4284.
Now that Bug#37148 has been reapplied to 6.0, try to make
it work with next-4284. This is also necessary to be able
to pull other changes from 5.1-rep into next-4284.
To resolve the merge issues use this changeset applied
to 6.0:
revid:jperkin@sun.com-20091216103628-ylhqf7s6yegui2t9
revno: 3776.1.1
committer: He Zhenxing <zhenxing.he@sun.com>
branch nick: 6.0-codebase-bugfixing
timestamp: Thu 2009-12-17 17:02:50 +0800
message:
Fix merge problem with Bug#37148
Conflicts:
- mysql-test/r/mysqld--help-win.result
- sql/sys_vars.cc
Original revsion (in next-mr-bugfixing):
------------------------------------------------------------
revno: 2971 [merge]
revision-id: alfranio.correia@sun.com-20100121210527-rbuheu5rnsmcakh1
committer: Alfranio Correia <alfranio.correia@sun.com>
branch nick: mysql-next-mr-bugfixing
timestamp: Thu 2010-01-21 21:05:27 +0000
message:
BUG#46364 MyISAM transbuffer problems (NTM problem)
It is well-known that due to concurrency issues, a slave can become
inconsistent when a transaction contains updates to both transaction and
non-transactional tables.
In a nutshell, the current code-base tries to preserve causality among the
statements by writing non-transactional statements to the txn-cache which
is flushed upon commit. However, modifications done to non-transactional
tables on behalf of a transaction become immediately visible to other
connections but may not immediately get into the binary log and therefore
consistency may be broken.
In general, it is impossible to automatically detect causality/dependency
among statements by just analyzing the statements sent to the server. This
happen because dependency may be hidden in the application code and it is
necessary to know a priori all the statements processed in the context of
a transaction such as in a procedure. Moreover, even for the few cases that
we could automatically address in the server, the computation effort
required could make the approach infeasible.
So, in this patch we introduce the option
- "--binlog-direct-non-transactional-updates" that can be used to bypass
the current behavior in order to write directly to binary log statements
that change non-transactional tables.
Besides, it is used to enable the WL#2687 which is disabled by default.
------------------------------------------------------------
revno: 2970.1.1
revision-id: alfranio.correia@sun.com-20100121131034-183r4qdyld7an5a0
parent: alik@sun.com-20100121083914-r9rz2myto3tkdya0
committer: Alfranio Correia <alfranio.correia@sun.com>
branch nick: mysql-next-mr-bugfixing
timestamp: Thu 2010-01-21 13:10:34 +0000
message:
BUG#46364 MyISAM transbuffer problems (NTM problem)
It is well-known that due to concurrency issues, a slave can become
inconsistent when a transaction contains updates to both transaction and
non-transactional tables.
In a nutshell, the current code-base tries to preserve causality among the
statements by writing non-transactional statements to the txn-cache which
is flushed upon commit. However, modifications done to non-transactional
tables on behalf of a transaction become immediately visible to other
connections but may not immediately get into the binary log and therefore
consistency may be broken.
In general, it is impossible to automatically detect causality/dependency
among statements by just analyzing the statements sent to the server. This
happen because dependency may be hidden in the application code and it is
necessary to know a priori all the statements processed in the context of
a transaction such as in a procedure. Moreover, even for the few cases that
we could automatically address in the server, the computation effort
required could make the approach infeasible.
So, in this patch we introduce the option
- "--binlog-direct-non-transactional-updates" that can be used to bypass
the current behavior in order to write directly to binary log statements
that change non-transactional tables.
Besides, it is used to enable the WL#2687 which is disabled by default.
The auto-inc unsafe warning makes sense even though it's just
one auto-inc table could be involved via a trigger or a stored
function.
However its content was not updated by bug@45677 fixes continuing to mention
two tables whereas the fixes refined semantics of replication of auto_increment
in stored routine.
Fixed with updating the error message, renaming the error and an internal unsafe-condition
constants.
A documentation notice
======================
Inserting into an autoincrement column in a stored function or a trigger
is unsafe for replication.
Even with just one autoincrement column, if the routine is invoked more than
once slave is not guaranteed to execute the statement graph same way as
the master.
And since it's impossible to estimate how many times a routine can be invoked at
the query pre-execution phase (see lock_tables), the statement is marked
pessimistically unsafe.
mysql-test/suite/binlog/r/binlog_stm_unsafe_warning.result:
results updated to include the expected unsafe warning.
mysql-test/suite/binlog/t/binlog_stm_unsafe_warning.test:
regression test for bug#50192 to diplaying the unsafe warning comes out to the user warning stack.
sql/share/errmsg-utf8.txt:
Updating the auto-inc unsafe message to correspond to bug@45677 fixes' new sematics.
sql/share/errmsg.txt:
Updating the auto-inc unsafe message to correspond to bug@45677 fixes' new sematics.
sql/sql_base.cc:
changing a symbolic name to correspond to updated by bug@45677 fixes new sematics.
sql/sql_lex.cc:
changing a symbolic name to correspond to updated by bug@45677 fixes new sematics.
sql/sql_lex.h:
changing a symbolic name to correspond to updated by bug@45677 fixes new sematics
and description comments.
Bug #45856 can't switch from binlog_format=row to mix with open tmp tbl
If binlog_format=MIXED, there are open temporary tables, an unsafe statement
is executed, and the user issues 'SET @@session.binlog_format = STATEMENT',
then subsequent DML statements will be written in row format despite
binlog_format=STATEMENT. Because the binlog format can't be reset to
statement based by 'reset_current_stmt_binlog_row_based' function.
If binlog_format=ROW, there are open temporary tables, and an unsafe statement
is executed, then the statement 'SET @@session.binlog_format = MIXED' generates
the error:
"Cannot switch out of the row-based binary log format when the session has open
temporary tables"
However, it is safe to switch to MIXED mode because events in row format are allowed.
To fix the above two problems, generate ER_TEMP_TABLE_PREVENTS_SWITCH_OUT_OF_RBR
and forbid switching from MIXED or ROW to STATEMENT when there are open temp
tables and we are logging in row format. There is no error in any other case.
mysql-test/suite/binlog/r/binlog_format_switch_in_tmp_table.result:
Test result for bug#45855 and bug#45856.
mysql-test/suite/binlog/t/binlog_format_switch_in_tmp_table.test:
Added test file to verify if the program will generate
ER_TEMP_TABLE_PREVENTS_SWITCH_OUT_OF_RBR error and forbid
switching from MIXED or ROW to STATEMENT when there are
open temp tables and we are logging in row format. There
is no error in any other case.
In RBR, DDL statement will change binlog format to non row-based
format before it is binlogged, but the binlog format was not be
restored, and then manipulating a temporary table can not reset binlog
format to row-based format rightly. So that the manipulated statement
is binlogged with statement-based format.
To fix the problem, restore the state of binlog format after the DDL
statement is binlogged.
mysql-test/extra/rpl_tests/rpl_tmp_table_and_DDL.test:
Added the test file to verify if executing DDL statement before
trying to manipulate a temporary table causes row-based replication
to break with error 'table does not exist'.
mysql-test/suite/binlog/r/binlog_row_mix_innodb_myisam.result:
Correct the test result, all the above binlog event
should be row-based after the bug49132 is fixed IN RBR.
mysql-test/suite/ndb/r/ndb_tmp_table_and_DDL.result:
Test result for bug#49132 base on ndb engine.
mysql-test/suite/ndb/t/ndb_tmp_table_and_DDL.test:
Added the test file to verify if executing DDL statement before
trying to manipulate a temporary table causes row-based replication
to break with error 'table does not exist' base on ndb engine.
mysql-test/suite/rpl/r/rpl_tmp_table_and_DDL.result:
Test result for bug#49132 base on myisam engine.
mysql-test/suite/rpl/t/rpl_tmp_table_and_DDL.test:
Added the test file to verify if executing DDL statement before
trying to manipulate a temporary table causes row-based replication
to break with error 'table does not exist' base on myisam engine.
sql/event_db_repository.cc:
Added code to restore the state of binlog format after the DDL
statement is binlogged.
sql/events.cc:
Added code to restore the state of binlog format after the DDL
statement is binlogged.
sql/sp.cc:
Added code to restore the state of binlog format after the DDL
statement is binlogged.
sql/sql_acl.cc:
Added code to restore the state of binlog format after the DDL
statement is binlogged.
sql/sql_udf.cc:
Added code to restore the state of binlog format after the DDL
statement is binlogged.
It is well-known that due to concurrency issues, a slave can become
inconsistent when a transaction contains updates to both transaction and
non-transactional tables.
In a nutshell, the current code-base tries to preserve causality among the
statements by writing non-transactional statements to the txn-cache which
is flushed upon commit. However, modifications done to non-transactional
tables on behalf of a transaction become immediately visible to other
connections but may not immediately get into the binary log and therefore
consistency may be broken.
In general, it is impossible to automatically detect causality/dependency
among statements by just analyzing the statements sent to the server. This
happen because dependency may be hidden in the application code and it is
necessary to know a priori all the statements processed in the context of
a transaction such as in a procedure. Moreover, even for the few cases that
we could automatically address in the server, the computation effort
required could make the approach infeasible.
So, in this patch we introduce the option
- "--binlog-direct-non-transactional-updates" that can be used to bypass
the current behavior in order to write directly to binary log statements
that change non-transactional tables.
Besides, it is used to enable the WL#2687 which is disabled by default.
mysql-test/extra/rpl_tests/rpl_binlog_max_cache_size.test:
Changes the result set as the STMT mode behaves as both the ROW and MIXED modes and as such uses the non-trx-cache and takes longer to fill the trx-cache up and trigger an error.
mysql-test/extra/rpl_tests/rpl_implicit_commit_binlog.test:
Changes the result set as the STMT mode behaves as both the ROW and MIXED modes and as such uses the non-trx-cache. It also fixes comments.
mysql-test/extra/rpl_tests/rpl_mixing_engines.test:
The STMT mode is unsafe when mixed-statements are executed thus making slaves to go out of sync. For that reason, it checks consistency if not in STMT mode.
mysql-test/include/default_mysqld.cnf:
Makes binlog-direct-non-transactional-updates "TRUE" by default in the test
cases.
mysql-test/r/mysqld--help-notwin.result:
Updates the result file with the new option.
mysql-test/r/mysqld--help-win.result:
Updates the result file with the new option.
mysql-test/suite/binlog/r/binlog_multi_engine.result:
Updates the result file because non-trx-changes are written ahead of the
transaction.
mysql-test/suite/binlog/r/binlog_switch_inside_trans.result:
Verifies if the user cannot change the opion binlog_direct_non_transactional_updates
within a transaction or a procedure/function/trigger.
mysql-test/suite/binlog/t/binlog_stm_mix_innodb_myisam-master.opt:
Sets binlog_direct_non_transactional_updates to FALSE in order to avoid changing
the test case and its result file.
mysql-test/suite/binlog/t/binlog_switch_inside_trans.test:
Verifies if the user cannot change the opion binlog_direct_non_transactional_updates
within a transaction or a procedure/function/trigger.
mysql-test/suite/ndb/r/ndb_binlog_format.result:
Updates the result file because non-trx-changes are written ahead of the
transaction.
mysql-test/suite/rpl/r/rpl_begin_commit_rollback.result:
Sets binlog_direct_non_transactional_updates to FALSE in order to avoid changing the test case and its result file.
mysql-test/suite/rpl/r/rpl_concurrency_error.result:
Updates the result file because non-trx-changes are written ahead of the
transaction
mysql-test/suite/rpl/r/rpl_mixed_implicit_commit_binlog.result:
Updates the result file because non-trx-changes are written ahead of the
transaction.
mysql-test/suite/rpl/r/rpl_mixed_mixing_engines.result:
Updates the result file because non-trx-changes are written ahead of the
transaction.
mysql-test/suite/rpl/r/rpl_stm_binlog_max_cache_size.result:
Changes the result set as the STMT mode behaves as both the ROW and MIXED modes and as such uses the non-trx-cache and takes longer to fill the trx-cache up and trigger an error.
mysql-test/suite/rpl/r/rpl_stm_implicit_commit_binlog.result:
Updates the result file because non-trx-changes are written ahead of the
transaction.
mysql-test/suite/rpl/r/rpl_stm_mixing_engines.result:
Updates the result file because non-trx-changes are written ahead of the
transaction.
mysql-test/suite/rpl/r/rpl_stm_start_stop_slave.result:
Sets binlog_direct_non_transactional_updates to FALSE in order to avoid changing the test case and its result file.
mysql-test/suite/rpl/r/rpl_stm_stop_middle_group.result:
Sets binlog_direct_non_transactional_updates to FALSE in order to avoid changing the test case and its result file.
mysql-test/suite/rpl/t/rpl_begin_commit_rollback.test:
Sets binlog_direct_non_transactional_updates to FALSE in order to avoid changing the test case and its result file.
mysql-test/suite/rpl/t/rpl_stm_start_stop_slave.test:
Sets binlog_direct_non_transactional_updates to FALSE in order to avoid changing the test case and its result file.
mysql-test/suite/rpl/t/rpl_stm_stop_middle_group.test:
Sets binlog_direct_non_transactional_updates to FALSE in order to avoid changing the test case and its result file.
sql/log.cc:
Verifies if changes should be written to either the trx-cache or non-trx-cache through the use of the function use_trans_cache(). It also organizes the code.
sql/log.h:
Changes the signature of some functions by adding the modifier "const" to the thd parameter. Specifically, the following functions are changed:
bool trans_has_updated_trans_table(const THD* thd);
bool stmt_has_updated_trans_table(const THD *thd);
bool use_trans_cache(const THD*, bool is_transactional);
sql/share/errmsg-utf8.txt:
Creates error messages to report when an user tries to change the new option
binlog_direct_non_transactional_updates within a transaction or a procedure/
function/trigger.
sql/share/errmsg.txt:
Creates error messages to report when an user tries to change the new option
binlog_direct_non_transactional_updates within a transaction or a procedure/
function/trigger.
sql/sql_class.h:
Adds the new option binlog_direct_non_transactional_updates.
sql/sys_vars.cc:
Adds the new option binlog_direct_non_transactional_updates.
support-files/my-small.cnf.sh:
Adds binlog-direct-non-transactional-updates to the example file. By default
the option is disabled.
Conflicts:
Text conflict in .bzr-mysql/default.conf
Text conflict in mysql-test/suite/rpl/r/rpl_loaddata_fatal.result
Text conflict in mysql-test/suite/rpl/r/rpl_stm_log.result
Text conflict in mysql-test/t/mysqlbinlog.test
Text conflict in sql/sql_acl.cc
Text conflict in sql/sql_servers.cc
Text conflict in sql/sql_update.cc
Text conflict in support-files/mysql.spec.sh
Problem: The test case failed because: (i) warning text in
result file differed from the warning output by the
server, and (ii) binlog contents in result file did
not show the statements logged wrapped in BEGIN/COMMIT
as it is the case after WL 2687.
Solution: We update the result file, but first we change the
unsafe warning text to also refer to performance_schema
table(s). This required changing the result files for
existing test cases that provide output for warnings
related to ER_BINLOG_UNSAFE_SYSTEM_TABLE. "Grepping" in
result files, shows that only binlog_unsafe contained
reference to such a warning.
We also update the result file with the missing
BEGIN/COMMIT statements.
Problem: When RAND() is binlogged in statement mode, the seed is
binlogged too, so the replication slave generates the same
sequence of random numbers. This makes replication work in many
cases, but not in all cases: the order of rows is not guaranteed
for, e.g., UPDATE or INSERT...SELECT statements, so the row data
will be different if master and slave retrieve the rows in
different orders.
Fix: Mark RAND() as unsafe. It will generate a warning if
binlog_format=STATEMENT and switch to row-logging if
binlog_format=ROW.
mysql-test/extra/rpl_tests/rpl_row_func003.test:
updated test case to ignore new warnings
mysql-test/suite/binlog/r/binlog_unsafe.result:
updated result file
mysql-test/suite/binlog/t/binlog_unsafe.test:
Added test for RAND().
Also clarified some old comments.
mysql-test/suite/rpl/r/rpl_misc_functions.result:
updated result file
mysql-test/suite/rpl/r/rpl_nondeterministic_functions.result:
updated test case to ignore new warnings
mysql-test/suite/rpl/r/rpl_optimize.result:
updated result file
mysql-test/suite/rpl/r/rpl_row_func003.result:
updated result file
mysql-test/suite/rpl/t/rpl_misc_functions.test:
updated test case to ignore new warnings
mysql-test/suite/rpl/t/rpl_nondeterministic_functions.test:
updated test case to ignore new warnings
mysql-test/suite/rpl/t/rpl_optimize.test:
updated test case to ignore new warnings
mysql-test/suite/rpl/t/rpl_trigger.test:
updated test case to ignore new warnings
mysql-test/suite/rpl_ndb/r/rpl_ndb_func003.result:
updated result file
sql/item_create.cc:
Mark RAND() unsafe.
Conflicts:
Text conflict in .bzr-mysql/default.conf
Text conflict in mysql-test/extra/rpl_tests/rpl_loaddata.test
Text conflict in mysql-test/r/mysqlbinlog2.result
Text conflict in mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result
Text conflict in mysql-test/suite/binlog/r/binlog_unsafe.result
Text conflict in mysql-test/suite/rpl/r/rpl_insert_id.result
Text conflict in mysql-test/suite/rpl/r/rpl_loaddata.result
Text conflict in mysql-test/suite/rpl/r/rpl_stm_auto_increment_bug33029.result
Text conflict in mysql-test/suite/rpl/r/rpl_udf.result
Text conflict in mysql-test/suite/rpl/t/rpl_slow_query_log.test
Text conflict in sql/field.h
Text conflict in sql/log.cc
Text conflict in sql/log_event.cc
Text conflict in sql/log_event_old.cc
Text conflict in sql/mysql_priv.h
Text conflict in sql/share/errmsg.txt
Text conflict in sql/sp.cc
Text conflict in sql/sql_acl.cc
Text conflict in sql/sql_base.cc
Text conflict in sql/sql_class.h
Text conflict in sql/sql_db.cc
Text conflict in sql/sql_delete.cc
Text conflict in sql/sql_insert.cc
Text conflict in sql/sql_lex.cc
Text conflict in sql/sql_lex.h
Text conflict in sql/sql_load.cc
Text conflict in sql/sql_table.cc
Text conflict in sql/sql_update.cc
Text conflict in sql/sql_view.cc
Conflict adding files to storage/innobase. Created directory.
Conflict because storage/innobase is not versioned, but has versioned children. Versioned directory.
Conflict adding file storage/innobase. Moved existing file to storage/innobase.moved.
Conflict adding files to storage/innobase/handler. Created directory.
Conflict because storage/innobase/handler is not versioned, but has versioned children. Versioned directory.
Contents conflict in storage/innobase/handler/ha_innodb.cc
For tables with metadata sizes ranging from 251 to 255 the size
of the event data (m_data_size) was being improperly calculated
in the Table_map_log_event constructor. This was due to the fact
that when writing the Table_map_log_event body (in
Table_map_log_event::write_data_body) a call to net_store_length
is made for packing the m_field_metadata_size. It happens that
net_store_length uses *one* byte for storing
m_field_metadata_size when it is smaller than 251 but *three*
bytes when it exceeds that value. BUG 42749 had already
pinpointed and fix this fact, but the fix was incomplete, as the
calculation in the Table_map_log_event constructor considers 255
instead of 251 as the threshold to increment m_data_size by
three. Thence, the window for having a mismatch between the
number of bytes written and the number of bytes accounted in the
event length (m_data_size) was left open for
m_field_metadata_size values between 251 and 255.
We fix this by changing the condition in the Table_map_log_event
constructor to match the one in the net_store_length, ie,
increment one byte if m_field_metadata_size < 251 and three if it
exceeds this value.
mysql-test/suite/rpl/r/rpl_row_tbl_metadata.result:
Updated result file.
mysql-test/suite/rpl/t/rpl_row_tbl_metadata.test:
Changes to the original test case: added slave and moved
file into the rpl suite.
New test case: replicates two tables one with 250 and
another with 252 metadata sizes. This exercises the usage
of 1 or 3 bytes while packing the m_field_metadata_size.
sql/log_event.cc:
Made the m_data_size calculation for the table map log event
to match the number of bytes used while packing the
m_field_metadata_size value (according to net_store_length
function in pack.c).
In auto-commit mode, updating both trx and non-trx tables (i.e. issuing a mixed
statement) causes the following sequence of events:
1 - "Flush trx changes" (MYSQL_BIN_LOG::write) - T1:
1.1 - mutex_lock (&LOCK_log)
1.2 - mutex_lock (&LOCK_prep_xids)
1.3 - increase prepared_xids
1.4 - mutex_unlock (&LOCK_prep_xids)
1.5 - mutex_unlock (&LOCK_log)
2 - "Flush non-trx changes" (MYSQL_BIN_LOG::write) - T1:
2.1 - mutex_lock (&LOCK_log)
2.2 - mutex_unlock (&LOCK_log)
3. "unlog" - T1
3.1 - mutex_lock (&LOCK_prep_xids)
3.2 - decrease prepared xids
3.3 - pthread_cond_signal(&COND_prep_xids);
3.4 - mutex_unlock (&LOCK_prep_xids)
The "FLUSH logs" command produces the following sequence of events:
1 - "FLUSH logs" command (MYSQL_BIN_LOG::new_file_impl) - user thread:
1.1 - mutex_lock (&LOCK_log)
1.2 - mutex_lock (&LOCK_prep_xids)
1.3 - while (prepared_xids) pthread_cond_wait(..., &LOCK_prep_xids);
1.4 - mutex_unlock (&LOCK_prep_xids)
1.5 - mutex_unlock (&LOCK_log)
A deadlock will arise if T1 flushes the trx changes and thus increases
prepared_xids but before it is able to continue the execution and flush the
non-trx changes, an user thread calls the "FLUSH logs" command and wait that
the prepared_xids is decreased and gets to zero. However, T1 cannot proceed
with the call to "Flush non-trx changes" because it will block in the mutex
"LOCK_log" and by consequence cannot complete the execution and call the
unlog to decrease the prepared_xids.
To fix the problem, we ensure that the non-trx changes are always flushed
before the trx changes.
Note that if you call "Flush non-trx changes" and a concurrent "FLUSH logs" is
issued, the "Flush non-trx changes" may block, but a deadlock will never happen
because the prepared_xids will eventually get to zero. Bottom line, there will
not be any transaction able to increase the prepared_xids because they will
block in the mutex "LOCK_log" (MYSQL_BIN_LOG::write) and those that increased
the prepared_xids will eventually commit and decrease the prepared_xids.
When @@session.binlog_format is modified inside a transaction,
it can cause slave to go out of sync.
To fix the problem, make the session variable 'binlog_format'
read-only inside a transaction.
mysql-test/suite/binlog/r/binlog_format_switch_inside_trans.result:
Test result for bug#47863.
mysql-test/suite/binlog/t/binlog_format_switch_inside_trans.test:
Added test file to verify if the session variable 'binlog_format'
is read-only inside a transaction and in sub-statements.
sql/set_var.cc:
Added code to make the session variable 'binlog_format'
read-only inside a transaction.
