columns without where/group
Simple SELECT with implicit grouping used to return many rows if
the query was ordered by the aggregated column in the SELECT
list. This was incorrect because queries with implicit grouping
should only return a single record.
The problem was that when JOIN:exec() decided if execution needed
to handle grouping, it was assumed that sum_func_count==0 meant
that there were no aggregate functions in the query. This
assumption was not correct in JOIN::exec() because the aggregate
functions might have been optimized away during JOIN::optimize().
The reason why queries without ordering behaved correctly was
that sum_func_count is only recalculated if the optimizer chooses
to use temporary tables (which it does in the ordered case).
Hence, non-ordered queries were correctly treated as grouped.
The fix for this bug was to remove the assumption that
sum_func_count==0 means that there is no need for grouping. This
was done by introducing variable "bool implicit_grouping" in the
JOIN object.
mysql-test/r/func_group.result:
Add test for BUG#47280
mysql-test/t/func_group.test:
Add test for BUG#47280
sql/opt_sum.cc:
Improve comment for opt_sum_query()
sql/sql_class.h:
Add comment for variables in TMP_TABLE_PARAM
sql/sql_select.cc:
Introduce and use variable implicit_grouping instead of (!group_list && sum_func_count) in places that need to test if grouping is required. Also added comments for: optimization of aggregate fields for implicitly grouped queries (JOIN::optimize) and choice of end_select method (JOIN::execute)
sql/sql_select.h:
Add variable implicit_grouping, which will be TRUE for queries that contain aggregate functions but no GROUP BY clause. Also added comment to sort_and_group variable.
columns without where/group
Simple SELECT with implicit grouping used to return many rows if
the query was ordered by the aggregated column in the SELECT
list. This was incorrect because queries with implicit grouping
should only return a single record.
The problem was that when JOIN:exec() decided if execution needed
to handle grouping, it was assumed that sum_func_count==0 meant
that there were no aggregate functions in the query. This
assumption was not correct in JOIN::exec() because the aggregate
functions might have been optimized away during JOIN::optimize().
The reason why queries without ordering behaved correctly was
that sum_func_count is only recalculated if the optimizer chooses
to use temporary tables (which it does in the ordered case).
Hence, non-ordered queries were correctly treated as grouped.
The fix for this bug was to remove the assumption that
sum_func_count==0 means that there is no need for grouping. This
was done by introducing variable "bool implicit_grouping" in the
JOIN object.
local storage for query cache).
We need more than one pointer in a thread to
represent the query cache and net->query_cache_query can not be used
any more (due to ABI compatibility issues and to different life
time of NET and THD).
This is a backport of the following patch from 6.0:
----------------------------------------------------------
revno: 2476.1157.2
committer: kostja@bodhi.(none)
timestamp: Sat 2007-06-16 13:29:24 +0400
include/mysql.h.pp:
Update the ABI (NET::query_cache_query is now unused).
include/mysql_com.h:
NET::query_cache_query is now unused.
sql/mysql_priv.h:
Update signatures of ex-functios now member functions.
sql/sql_cache.cc:
Introduce THD::query_cache_tls.
sql/sql_cache.h:
Introduce THD::query_cache_tls.
sql/sql_class.cc:
Introduce THD::query_cache_tls.
sql/sql_class.h:
Introduce THD::query_cache_tls.
sql/sql_parse.cc:
Use THD::query_cache_tls.
sql/sql_select.cc:
Use THD::query_cache_tls.
local storage for query cache).
We need more than one pointer in a thread to
represent the query cache and net->query_cache_query can not be used
any more (due to ABI compatibility issues and to different life
time of NET and THD).
This is a backport of the following patch from 6.0:
----------------------------------------------------------
revno: 2476.1157.2
committer: kostja@bodhi.(none)
timestamp: Sat 2007-06-16 13:29:24 +0400
storing and restoring information about foreign keys in the .FRM files and
properly displaying it in SHOW CREATE TABLE output and I_S tables.
The idea of this patch is to change type of Key_part_spec::field_name and
Key::name to LEX_STRING in order to avoid extra strlen() calls during
semantic analysis and statement execution, particularly, in code to be
implemented on the 2nd milestone of WL#148.
Note that since we are not using LEX_STRING everywhere yet (e.g. in
Create_field and KEY) and we want to limit scope of our changes we
have to do strlen() in places where we create Key and Key_part_spec
instances from objects using plain (char*) for strings. These calls
will go away during the process of further (char*) -> LEX_STRING
refactoring.
We have introduced these changes in 6.0 and backported them to 5.5
tree to make people aware of these changes as early as possible and
to simplify merges with mysql-fk and mysql-6.1-fk trees.
No test case is needed since this patch does not introduce any
user visible changes.
sql/sql_class.cc:
Key_part_spec::field_name is now LEX_STRING. Adjusted code accordingly.
sql/sql_class.h:
Changed type of Key_part_spec::field_name and Key::name to LEX_STRING in
order to avoid extra strlen() calls in code responsible for semantic
analysis and statement execution (e.g. in future code responsible for
saving/restoring info about foreign keys).
sql/sql_lex.cc:
Moved null_lex_str from sql_yacc.yy to sql_lex.cc and added its
declaration to sql_lex.h to make it accessible in other SQL-layer
modules (e.g. sql_parse.cc).
sql/sql_lex.h:
Made null_lex_str accessible from outside of sql_lex.cc.
sql/sql_parse.cc:
Key_part_spec::field_name and Key::name are now LEX_STRING. Adjusted
code accordingly.
sql/sql_table.cc:
Adjusted code to accomodate change of type to LEX_STRING for
Key_part_spec::field_name and Key::name.
sql/sql_yacc.yy:
Now Key::name and Key_part_spec::field_name are LEX_STRINGs. Adjusted
grammar to be able properly initialize them. This should allow us to
save on some strlen() calls during later stages of statement execution.
storing and restoring information about foreign keys in the .FRM files and
properly displaying it in SHOW CREATE TABLE output and I_S tables.
The idea of this patch is to change type of Key_part_spec::field_name and
Key::name to LEX_STRING in order to avoid extra strlen() calls during
semantic analysis and statement execution, particularly, in code to be
implemented on the 2nd milestone of WL#148.
Note that since we are not using LEX_STRING everywhere yet (e.g. in
Create_field and KEY) and we want to limit scope of our changes we
have to do strlen() in places where we create Key and Key_part_spec
instances from objects using plain (char*) for strings. These calls
will go away during the process of further (char*) -> LEX_STRING
refactoring.
We have introduced these changes in 6.0 and backported them to 5.5
tree to make people aware of these changes as early as possible and
to simplify merges with mysql-fk and mysql-6.1-fk trees.
No test case is needed since this patch does not introduce any
user visible changes.
"have_profiling"
1) Renamed have_community_features server system variable to
have_profiling.
2) Removed eable-community-features configure option and
ENABLE_COMMUNITY_FEATURES macro.
3) Removed COMMUNITY_SERVER macro and replaced its usage by
ENABLED_PROFILING.
Only --enable-profiling is now needed to enable profiling.
It was the only existing "community feature", so there was
no need for both configure options.
Using --enable-community-features will give a warning message
since it no longer exists.
"have_profiling"
1) Renamed have_community_features server system variable to
have_profiling.
2) Removed eable-community-features configure option and
ENABLE_COMMUNITY_FEATURES macro.
3) Removed COMMUNITY_SERVER macro and replaced its usage by
ENABLED_PROFILING.
Only --enable-profiling is now needed to enable profiling.
It was the only existing "community feature", so there was
no need for both configure options.
Using --enable-community-features will give a warning message
since it no longer exists.
Backport from 6.0 to 5.1.
Only those sync points are included, which are used in debug_sync.test.
The Debug Sync Facility allows to place synchronization points
in the code:
open_tables(...)
DEBUG_SYNC(thd, "after_open_tables");
lock_tables(...)
When activated, a sync point can
- Send a signal and/or
- Wait for a signal
Nomenclature:
- signal: A value of a global variable that persists
until overwritten by a new signal. The global
variable can also be seen as a "signal post"
or "flag mast". Then the signal is what is
attached to the "signal post" or "flag mast".
- send a signal: Assign the value (the signal) to the global
variable ("set a flag") and broadcast a
global condition to wake those waiting for
a signal.
- wait for a signal: Loop over waiting for the global condition until
the global value matches the wait-for signal.
Please find more information in the top comment in debug_sync.cc
or in the worklog entry.
.bzrignore:
WL#4259 - Debug Sync Facility
Added the symbolic link libmysqld/debug_sync.cc.
CMakeLists.txt:
WL#4259 - Debug Sync Facility
Added definition for ENABLED_DEBUG_SYNC.
configure.in:
WL#4259 - Debug Sync Facility
Added definition for ENABLED_DEBUG_SYNC.
include/my_sys.h:
WL#4259 - Debug Sync Facility
Added definition for the DEBUG_SYNC_C macro.
libmysqld/CMakeLists.txt:
WL#4259 - Debug Sync Facility
Added sql/debug_sync.cc.
libmysqld/Makefile.am:
WL#4259 - Debug Sync Facility
Added sql/debug_sync.cc.
mysql-test/include/have_debug_sync.inc:
WL#4259 - Debug Sync Facility
New include file.
mysql-test/mysql-test-run.pl:
WL#4259 - Debug Sync Facility
Added option --debug_sync_timeout.
mysql-test/r/debug_sync.result:
WL#4259 - Debug Sync Facility
New test result.
mysql-test/r/have_debug_sync.require:
WL#4259 - Debug Sync Facility
New require file.
mysql-test/t/debug_sync.test:
WL#4259 - Debug Sync Facility
New test file.
mysys/my_static.c:
WL#4259 - Debug Sync Facility
Added definition for debug_sync_C_callback_ptr.
mysys/thr_lock.c:
WL#4259 - Debug Sync Facility
Added sync point "wait_for_lock".
sql/CMakeLists.txt:
WL#4259 - Debug Sync Facility
Added debug_sync.cc and debug_sync.h.
sql/Makefile.am:
WL#4259 - Debug Sync Facility
Added debug_sync.cc and debug_sync.h.
sql/debug_sync.cc:
WL#4259 - Debug Sync Facility
New source file.
sql/debug_sync.h:
WL#4259 - Debug Sync Facility
New header file.
sql/mysqld.cc:
WL#4259 - Debug Sync Facility
Added opt_debug_sync_timeout.
Added calls to debug_sync_init() and debug_sync_end().
Fixed a purecov comment (unrelated).
sql/set_var.cc:
WL#4259 - Debug Sync Facility
Added server variable "debug_sync".
sql/set_var.h:
WL#4259 - Debug Sync Facility
Added declaration for server variable "debug_sync".
sql/share/errmsg.txt:
WL#4259 - Debug Sync Facility
Added error messages ER_DEBUG_SYNC_TIMEOUT and ER_DEBUG_SYNC_HIT_LIMIT.
sql/sql_base.cc:
WL#4259 - Debug Sync Facility
Added sync points "after_flush_unlock" and "before_lock_tables_takes_lock".
sql/sql_class.cc:
WL#4259 - Debug Sync Facility
Added initialization for debug_sync_control to THD::THD.
Added calls to debug_sync_init_thread() and debug_sync_end_thread().
sql/sql_class.h:
WL#4259 - Debug Sync Facility
Added element debug_sync_control to THD.
storage/myisam/myisamchk.c:
Fixed a typo in an error message string (unrelated).
Backport from 6.0 to 5.1.
Only those sync points are included, which are used in debug_sync.test.
The Debug Sync Facility allows to place synchronization points
in the code:
open_tables(...)
DEBUG_SYNC(thd, "after_open_tables");
lock_tables(...)
When activated, a sync point can
- Send a signal and/or
- Wait for a signal
Nomenclature:
- signal: A value of a global variable that persists
until overwritten by a new signal. The global
variable can also be seen as a "signal post"
or "flag mast". Then the signal is what is
attached to the "signal post" or "flag mast".
- send a signal: Assign the value (the signal) to the global
variable ("set a flag") and broadcast a
global condition to wake those waiting for
a signal.
- wait for a signal: Loop over waiting for the global condition until
the global value matches the wait-for signal.
Please find more information in the top comment in debug_sync.cc
or in the worklog entry.
NOTE: Backporting the patch to next-mr.
WL#4828 Augment DBUG_ENTER/DBUG_EXIT to crash MySQL in different functions
-------
The assessment of the replication code in the presence of faults is extremely
import to increase reliability. In particular, one needs to know if servers
will either correctly recovery or print out appropriate error messages thus
avoiding unexpected problems in a production environment.
In order to accomplish this, the current patch refactories the debug macros
already provided in the source code and introduces three new macros that
allows to inject faults, specifically crashes, while entering or exiting a
function or method. For instance, to crash a server while returning from
the init_slave function (see module sql/slave.cc), one needs to do what
follows:
1 - Modify the source replacing DBUG_RETURN by DBUG_CRASH_RETURN;
DBUG_CRASH_RETURN(0);
2 - Use the debug variable to activate dbug instructions:
SET SESSION debug="+d,init_slave_crash_return";
The new macros are briefly described below:
DBUG_CRASH_ENTER (function) is equivalent to DBUG_ENTER which registers the
beginning of a function but in addition to it allows for crashing the server
while entering the function if the appropriate dbug instruction is activate.
In this case, the dbug instruction should be "+d,function_crash_enter".
DBUG_CRASH_RETURN (value) is equivalent to DBUG_RETURN which notifies the
end of a function but in addition to it allows for crashing the server
while returning from the function if the appropriate dbug instruction is
activate. In this case, the dbug instruction should be
"+d,function_crash_return". Note that "function" should be the same string
used by either the DBUG_ENTER or DBUG_CRASH_ENTER.
DBUG_CRASH_VOID_RETURN (value) is equivalent to DBUG_VOID_RETURN which
notifies the end of a function but in addition to it allows for crashing
the server while returning from the function if the appropriate dbug
instruction is activate. In this case, the dbug instruction should be
"+d,function_crash_return". Note that "function" should be the same string
used by either the DBUG_ENTER or DBUG_CRASH_ENTER.
To inject other faults, for instance, wrong return values, one should rely
on the macros already available. The current patch also removes a set of
macros that were either not being used or were redundant as other macros
could be used to provide the same feature. In the future, we also consider
dynamic instrumentation of the code.
BUG#45747 DBUG_CRASH_* is not setting the strict option
---------
When combining DBUG_CRASH_* with "--debug=d:t:i:A,file" the server crashes
due to a call to the abort function in the DBUG_CRASH_* macro althought the
appropriate keyword has not been set.
NOTE: Backporting the patch to next-mr.
WL#4828 Augment DBUG_ENTER/DBUG_EXIT to crash MySQL in different functions
-------
The assessment of the replication code in the presence of faults is extremely
import to increase reliability. In particular, one needs to know if servers
will either correctly recovery or print out appropriate error messages thus
avoiding unexpected problems in a production environment.
In order to accomplish this, the current patch refactories the debug macros
already provided in the source code and introduces three new macros that
allows to inject faults, specifically crashes, while entering or exiting a
function or method. For instance, to crash a server while returning from
the init_slave function (see module sql/slave.cc), one needs to do what
follows:
1 - Modify the source replacing DBUG_RETURN by DBUG_CRASH_RETURN;
DBUG_CRASH_RETURN(0);
2 - Use the debug variable to activate dbug instructions:
SET SESSION debug="+d,init_slave_crash_return";
The new macros are briefly described below:
DBUG_CRASH_ENTER (function) is equivalent to DBUG_ENTER which registers the
beginning of a function but in addition to it allows for crashing the server
while entering the function if the appropriate dbug instruction is activate.
In this case, the dbug instruction should be "+d,function_crash_enter".
DBUG_CRASH_RETURN (value) is equivalent to DBUG_RETURN which notifies the
end of a function but in addition to it allows for crashing the server
while returning from the function if the appropriate dbug instruction is
activate. In this case, the dbug instruction should be
"+d,function_crash_return". Note that "function" should be the same string
used by either the DBUG_ENTER or DBUG_CRASH_ENTER.
DBUG_CRASH_VOID_RETURN (value) is equivalent to DBUG_VOID_RETURN which
notifies the end of a function but in addition to it allows for crashing
the server while returning from the function if the appropriate dbug
instruction is activate. In this case, the dbug instruction should be
"+d,function_crash_return". Note that "function" should be the same string
used by either the DBUG_ENTER or DBUG_CRASH_ENTER.
To inject other faults, for instance, wrong return values, one should rely
on the macros already available. The current patch also removes a set of
macros that were either not being used or were redundant as other macros
could be used to provide the same feature. In the future, we also consider
dynamic instrumentation of the code.
BUG#45747 DBUG_CRASH_* is not setting the strict option
---------
When combining DBUG_CRASH_* with "--debug=d:t:i:A,file" the server crashes
due to a call to the abort function in the DBUG_CRASH_* macro althought the
appropriate keyword has not been set.
trigger, merge table
The problem with break statements is that they have very
local effects. Hence a break statement within the inner loop
of a nested-loops join caused execution to proceed to the
next table even though a serious error occurred. The problem
was fixed by breaking out the inner loop into its own
method. The change empowers all errors to terminate the
execution.
The errors that will now halt multi-DELETE execution
altogether are
- triggers returning errors
- handler errors
- server being killed
mysql-test/r/delete.result:
Bug#46958: Test result.
mysql-test/t/delete.test:
Bug#46958: Test case.
sql/sql_class.h:
Bug#46958: New method declaration.
sql/sql_delete.cc:
Bug#46958: New method implementation.
trigger, merge table
The problem with break statements is that they have very
local effects. Hence a break statement within the inner loop
of a nested-loops join caused execution to proceed to the
next table even though a serious error occurred. The problem
was fixed by breaking out the inner loop into its own
method. The change empowers all errors to terminate the
execution.
The errors that will now halt multi-DELETE execution
altogether are
- triggers returning errors
- handler errors
- server being killed
partial backport of bug43138 fix
mysql-test/r/warnings.result:
test result
mysql-test/t/warnings.test:
test case
sql/sql_class.cc:
partial backport of bug43138 fix
sql/sql_class.h:
partial backport of bug43138 fix
sql/sql_table.cc:
partial backport of bug43138 fix
* Finished Monty and Jani's merge
* Some InnoDB tests still fail (because it's old xtradb code run against
newer testsuite). They are expected to go after mergning with the latest
xtradb.
Added (rewritten) patch from Percona to get extended statistics in slow.log:
- Added handling of 'set' variables to set_var.cc. Changed sql_mode to use this
- Added extra logging to slow log of 'Thread_id, Schema, Query Cache hit, Rows sent and Rows examined'
- Added optional logging to slow log, through log_slow_verbosity, of query plan statistics
- Added new user variables log_slow_rate_limit, log_slow_verbosity, log_slow_filter
- Added log-slow-file as synonym for 'slow-log-file', as most slow-log variables starts with 'log-slow'
- Added log-slow-time as synonym for long-query-time
Some trivial MyISAM optimizations:
- In prepare for drop, flush key blocks
- Don't call mi_lock_database if my_disable_locking is used
KNOWN_BUGS.txt:
Updated file to reflect MariaDB and not the Maria storage engine
README:
Updated file to reflect MariaDB
mysql-test/r/log_slow.result:
Test new options for slow query log
mysql-test/r/variables.result:
Updated result (old version cut of things at 79 characters)
mysql-test/t/log_slow.test:
Test new options for slow query log
sql/Makefile.am:
Added log_slow.h
sql/event_data_objects.cc:
Removed not needed test for enable_slow_log (is done when the flag is tested elsewhere)
sql/events.cc:
Use the general make_set() function instead of 'symbolic_mode_representation'
sql/filesort.cc:
Added status for used query plans
sql/log.cc:
Reset counters if no query_length (from Percona's patch; Not sure if needed, but can do no harm)
Added extra logging to slow log of 'Thread_id, Schema, Query Cache hit, Rows sent and Rows examined'
Added optional logging to slow log, through log_slow_verbosity, of query plan statistics
Fixed wrong test of error condition
sql/log_slow.h:
Defines and variables for log_slow_verbosity and log_slow_filter
sql/mysql_priv.h:
Include log_slow.h
sql/mysqld.cc:
Added new user variables log_slow_rate_limit, log_slow_verbosity, log_slow_filter
Added log-slow-file as synonym for 'slow-log-file', as most slow-log variables starts with 'log-slow'
Added log-slow-time as synonym for long-query-time
Added note that one should use log-slow-filter instead of log-slow-admin-statements
Updated comment from 'slow_query_log_file'
sql/set_var.cc:
Added long_slow_time as synonym for long_query_time
Added new user variables log_slow_rate_limit, log_slow_verbosity, log_slow_filter
dded handling of 'set' variables to set_var.cc. Changed sql_mode to use this
sql/set_var.h:
- Added handling of 'set' variables. Changed sql_mode to use this
sql/slave.cc:
Use global filter also for slaves
sql/sp_head.cc:
Simplify saving of general_slow_log state
Use the general make_set() function instead of 'symbolic_mode_representation'
sql/sql_cache.cc:
Added status for used query plans
sql/sql_class.cc:
Remember/restore query_plan_flags over complex statements
sql/sql_class.h:
Added variables to handle extended slow log statistics
sql/sql_parse.cc:
Added status for used query plans
Added test for filtering slow_query_log
sql/sql_select.cc:
Added status for used query plans
sql/sql_show.cc:
Use the general make_set() function instead of 'symbolic_mode_representation'
sql/strfunc.cc:
Report first error (not last) if something is wrong in a set
Removed compiler warning
storage/myisam/mi_extra.c:
In prepare for drop, flush key blocks (speed optimization)
storage/myisam/mi_locking.c:
Don't call mi_lock_database if my_disable_locking is used (speed optimization)
bzr branch mysql-5.1-performance-version mysql-trunk # Summit
cd mysql-trunk
bzr merge mysql-5.1-innodb_plugin # which is 5.1 + Innodb plugin
bzr rm innobase # remove the builtin
Next step: build, test fixes.
bzr branch mysql-5.1-performance-version mysql-trunk # Summit
cd mysql-trunk
bzr merge mysql-5.1-innodb_plugin # which is 5.1 + Innodb plugin
bzr rm innobase # remove the builtin
Next step: build, test fixes.
when used with --tab
1) New syntax: added CHARACTER SET clause to the
SELECT ... INTO OUTFILE (to complement the same clause in
LOAD DATA INFILE).
mysqldump is updated to use this in --tab mode.
2) ESCAPED BY/ENCLOSED BY field parameters are documented as
accepting CHAR argument, however SELECT .. INTO OUTFILE
silently ignored rests of multisymbol arguments.
For the symmetrical behavior with LOAD DATA INFILE the
server has been modified to fail with the same error:
ERROR 42000: Field separator argument is not what is
expected; check the manual
3) Current LOAD DATA INFILE recognizes field/line separators
"as is" without converting from client charset to data
file charset. So, it is supposed, that input file of
LOAD DATA INFILE consists of data in one charset and
separators in other charset. For the compatibility with
that [buggy] behaviour SELECT INTO OUTFILE implementation
has been saved "as is" too, but the new warning message
has been added:
Non-ASCII separator arguments are not fully supported
This message warns on field/line separators that contain
non-ASCII symbols.
client/mysqldump.c:
mysqldump has been updated to call SELECT ... INTO OUTFILE
statement with a charset from the --default-charset command
line parameter.
mysql-test/r/mysqldump.result:
Added test case for bug #30946.
mysql-test/r/outfile_loaddata.result:
Added test case for bug #30946.
mysql-test/t/mysqldump.test:
Added test case for bug #30946.
mysql-test/t/outfile_loaddata.test:
Added test case for bug #30946.
sql/field.cc:
String conversion code has been moved from check_string_copy_error()
to convert_to_printable() for reuse.
sql/share/errmsg.txt:
New WARN_NON_ASCII_SEPARATOR_NOT_IMPLEMENTED message has been added.
sql/sql_class.cc:
The select_export::prepare() method has been modified to:
1) raise the ER_WRONG_FIELD_TERMINATORS error on multisymbol
ENCLOSED BY/ESCAPED BY field arguments like LOAD DATA INFILE;
2) warn with a new WARN_NON_ASCII_SEPARATOR_NOT_IMPLEMENTED
message on non-ASCII field or line separators.
The select_export::send_data() merhod has been modified to
convert item data to output charset (see new SELECT INTO OUTFILE
syntax). By default the BINARY charset is used for backward
compatibility.
sql/sql_class.h:
The select_export::write_cs field added to keep output
charset.
sql/sql_load.cc:
mysql_load has been modified to warn on non-ASCII field or
line separators with a new WARN_NON_ASCII_SEPARATOR_NOT_IMPLEMENTED
message.
sql/sql_string.cc:
New global function has been added: convert_to_printable()
(common code has been moved from check_string_copy_error()).
sql/sql_string.h:
New String::is_ascii() method and new global convert_to_printable()
function have been added.
sql/sql_yacc.yy:
New syntax: added CHARACTER SET clause to the
SELECT ... INTO OUTFILE (to complement the same clause in
LOAD DATA INFILE). By default the BINARY charset is used for
backward compatibility.
