CONSISTENT SNAPSHOT OPTION
A transaction is started with a consistent snapshot. After
the transaction is started new indexes are added to the
table. Now when we issue an update statement, the optimizer
chooses an index. When the index scan is being initialized
via ha_innobase::change_active_index(), InnoDB reports
the error code HA_ERR_TABLE_DEF_CHANGED, with message
stating that "insufficient history for index".
This error message is propagated up to the SQL layer. But
the my_error() api is never called. The statement level
diagnostics area is not updated with the correct error
status (it remains in Diagnostics_area::DA_EMPTY).
Hence the following check in the Protocol::end_statement()
fails.
516 case Diagnostics_area::DA_EMPTY:
517 default:
518 DBUG_ASSERT(0);
519 error= send_ok(thd->server_status, 0, 0, 0, NULL);
520 break;
The fix is to backport the fix of bugs 14365043, 11761652
and 11746399.
14365043 PROTOCOL::END_STATEMENT(): ASSERTION `0' FAILED
11761652 HA_RND_INIT() RESULT CODE NOT CHECKED
11746399 RETURN VALUES OF HA_INDEX_INIT() AND INDEX_INIT() IGNORED
rb://1227 approved by guilhem and mattiasj.
When resolving outer fields, Item_field::fix_outer_fields()
creates new Item_refs for each execution of a prepared statement, so
these must be allocated in the runtime memroot. The memroot switching
before resolving JOIN::having causes these to be allocated in the
statement root, leaking memory for each PS execution.
sql/item_subselect.cc:
addon, fix for 11829691, item could be created in
runtime memroot, so we need to use real_item instead.
A defect in the subquery substitution code may lead to a server crash:
setting substitution's name should be followed by setting its length
(to keep them in sync).
mysql-test/r/gis.result:
BUG#12537203 - CRASH WHEN SUBSELECTING GLOBAL VARIABLES IN GEOMETRY FUNCTION ARGUMENTS
test result.
mysql-test/t/gis.test:
BUG#12537203 - CRASH WHEN SUBSELECTING GLOBAL VARIABLES IN GEOMETRY FUNCTION ARGUMENTS
test case.
sql/item_subselect.cc:
BUG#12537203 - CRASH WHEN SUBSELECTING GLOBAL VARIABLES IN GEOMETRY FUNCTION ARGUMENTS
set substitution's name length as well as the name itself (to keep them in sync).
Problematic query:
insert ignore into `t1_federated` (`c1`) select `c1` from `t1_local` a
where not exists (select 1 from `t1_federated` b where a.c1 = b.c1);
When this query is killed in another connection it could lead to crash.
The problem is follwing:
An attempt to obtain table statistics for subselect table in killed query
fails with an error. So JOIN::optimize() for subquery is failed but
it does not prevent further subquery evaluation.
At the first subquery execution JOIN::optimize() is called
(see subselect_single_select_engine::exec()) and fails with
an error. 'executed' flag is set to TRUE and it prevents
further subquery evaluation. At the second call
JOIN::optimize() does not happen as 'JOIN::optimized' is TRUE
and in case of uncacheable subquery the 'executed' flag is set
to FALSE before subquery evaluation. So we loose 'optimize stage'
error indication (see subselect_single_select_engine::exec()).
In other words 'executed' flag is used for two purposes, for
error indication at JOIN::optimize() stage and for an
indication of subquery execution. And it seems it's wrong
as the flag could be reset.
mysql-test/r/error_simulation.result:
test case
mysql-test/t/error_simulation.test:
test case
sql/item_subselect.cc:
added new flag subselect_single_select_engine::optimize_error
which is used for error detection which could happen at optimize
stage.
sql/item_subselect.h:
added new flag subselect_single_select_engine::optimize_error
sql/sql_select.cc:
test case
The query was re-written *after* we had tagged it with NON_AGG_FIELD_USED.
Remove the flag before continuing.
mysql-test/r/explain.result:
Update test case for Bug#48295.
mysql-test/r/subselect.result:
New test case.
mysql-test/t/explain.test:
Update test case for Bug#48295.
mysql-test/t/subselect.test:
New test case.
sql/item.cc:
Use accessor functions for non_agg_field_used/agg_func_used.
sql/item_subselect.cc:
Remove non_agg_field_used when we rewrite query '1 < some (...)' => '1 < max(...)'
sql/item_sum.cc:
Use accessor functions for non_agg_field_used/agg_func_used.
sql/mysql_priv.h:
Remove unused #defines.
sql/sql_lex.cc:
Initialize new member variables.
sql/sql_lex.h:
Replace full_group_by_flag with two boolean flags,
and itroduce accessors for manipulating them.
sql/sql_select.cc:
Use accessor functions for non_agg_field_used/agg_func_used.
This assumption in Item_cache_datetime::cache_value_int
was wrong:
- /* Assume here that the underlying item will do correct conversion.*/
- int_value= example->val_int_result();
mysql-test/r/subselect_innodb.result:
New test case.
mysql-test/t/subselect_innodb.test:
New test case.
sql/item.cc:
In Item_cache_datetime::cache_value_int()
- call get_time() or get_date() depending on desired type
- convert the returned MYSQL_TIME value to longlong depending on desired type
sql/item.h:
The cached int_value in Item_cache_datetime should not be unsigned:
- it is used mostly in signed context
- it can actually have negative value (for TIME data type)
sql/item_cmpfunc.cc:
Add comment on Bug#59685
sql/item_subselect.cc:
Add some DBUG_TRACE for easier bug-hunting.
If the ::single_value_transformer() find an existing HAVING condition it used
to do the transformation:
1) HAVING cond -> (HAVING Cond) AND (cond_guard (Item_ref_null_helper(...))
As the AND condition in 1) is Mc'Carty evaluated, the
right side of the AND cond should be executed only if the
original 'HAVING evaluated' to true.
However, as we failed to set 'top_level' for the tranformed HAVING condition,
'abort_on_null' was FALSE after transformation. An
UNKNOWN having condition will then not terminate evaluation of the
transformed having condition, and we incorrectly continued
into the Item_ref_null_helper() part.
- Removed files specific to compiling on OS/2
- Removed files specific to SCO Unix packaging
- Removed "libmysqld/copyright", text is included in documentation
- Removed LaTeX headers for NDB Doxygen documentation
- Removed obsolete NDB files
- Removed "mkisofs" binaries
- Removed the "cvs2cl.pl" script
- Changed a few GPL texts to use "program" instead of "library"
--Bug#52157 various crashes and assertions with multi-table update, stored function
--Bug#54475 improper error handling causes cascading crashing failures in innodb/ndb
--Bug#57703 create view cause Assertion failed: 0, file .\item_subselect.cc, line 846
--Bug#57352 valgrind warnings when creating view
--Recently discovered problem when a nested materialized derived table is used
before being populated and it leads to incorrect result
We have several modes when we should disable subquery evaluation.
The reasons for disabling are different. It could be
uselessness of the evaluation as in case of 'CREATE VIEW'
or 'PREPARE stmt', or we should disable subquery evaluation
if tables are not locked yet as it happens in bug#54475, or
too early evaluation of subqueries can lead to wrong result
as it happened in Bug#19077.
Main problem is that if subquery items are treated as const
they are evaluated in ::fix_fields(), ::fix_length_and_dec()
of the parental items as a lot of these methods have
Item::val_...() calls inside.
We have to make subqueries non-const to prevent unnecessary
subquery evaluation. At the moment we have different methods
for this. Here is a list of these modes:
1. PREPARE stmt;
We use UNCACHEABLE_PREPARE flag.
It is set during parsing in sql_parse.cc, mysql_new_select() for
each SELECT_LEX object and cleared at the end of PREPARE in
sql_prepare.cc, init_stmt_after_parse(). If this flag is set
subquery becomes non-const and evaluation does not happen.
2. CREATE|ALTER VIEW, SHOW CREATE VIEW, I_S tables which
process FRM files
We use LEX::view_prepare_mode field. We set it before
view preparation and check this flag in
::fix_fields(), ::fix_length_and_dec().
Some bugs are fixed using this approach,
some are not(Bug#57352, Bug#57703). The problem here is
that we have a lot of ::fix_fields(), ::fix_length_and_dec()
where we use Item::val_...() calls for const items.
3. Derived tables with subquery = wrong result(Bug19077)
The reason of this bug is too early subquery evaluation.
It was fixed by adding Item::with_subselect field
The check of this field in appropriate places prevents
const item evaluation if the item have subquery.
The fix for Bug19077 fixes only the problem with
convert_constant_item() function and does not cover
other places(::fix_fields(), ::fix_length_and_dec() again)
where subqueries could be evaluated.
Example:
CREATE TABLE t1 (i INT, j BIGINT);
INSERT INTO t1 VALUES (1, 2), (2, 2), (3, 2);
SELECT * FROM (SELECT MIN(i) FROM t1
WHERE j = SUBSTRING('12', (SELECT * FROM (SELECT MIN(j) FROM t1) t2))) t3;
DROP TABLE t1;
4. Derived tables with subquery where subquery
is evaluated before table locking(Bug#54475, Bug#52157)
Suggested solution is following:
-Introduce new field LEX::context_analysis_only with the following
possible flags:
#define CONTEXT_ANALYSIS_ONLY_PREPARE 1
#define CONTEXT_ANALYSIS_ONLY_VIEW 2
#define CONTEXT_ANALYSIS_ONLY_DERIVED 4
-Set/clean these flags when we perform
context analysis operation
-Item_subselect::const_item() returns
result depending on LEX::context_analysis_only.
If context_analysis_only is set then we return
FALSE that means that subquery is non-const.
As all subquery types are wrapped by Item_subselect
it allow as to make subquery non-const when
it's necessary.
mysql-test/r/derived.result:
test case
mysql-test/r/multi_update.result:
test case
mysql-test/r/view.result:
test case
mysql-test/suite/innodb/r/innodb_multi_update.result:
test case
mysql-test/suite/innodb/t/innodb_multi_update.test:
test case
mysql-test/suite/innodb_plugin/r/innodb_multi_update.result:
test case
mysql-test/suite/innodb_plugin/t/innodb_multi_update.test:
test case
mysql-test/t/derived.test:
test case
mysql-test/t/multi_update.test:
test case
mysql-test/t/view.test:
test case
sql/item.cc:
--removed unnecessary code
sql/item_cmpfunc.cc:
--removed unnecessary checks
--THD::is_context_analysis_only() is replaced with LEX::is_ps_or_view_context_analysis()
sql/item_func.cc:
--refactored context analysis checks
sql/item_row.cc:
--removed unnecessary checks
sql/item_subselect.cc:
--removed unnecessary code
--added DBUG_ASSERT into Item_subselect::exec()
which asserts that subquery execution can not happen
if LEX::context_analysis_only is set, i.e. at context
analysis stage.
--Item_subselect::const_item()
Return FALSE if LEX::context_analysis_only is set.
It prevents subquery evaluation in ::fix_fields &
::fix_length_and_dec at context analysis stage.
sql/item_subselect.h:
--removed unnecessary code
sql/mysql_priv.h:
--Added new set of flags.
sql/sql_class.h:
--removed unnecessary code
sql/sql_derived.cc:
--added LEX::context_analysis_only analysis intialization/cleanup
sql/sql_lex.cc:
--init LEX::context_analysis_only field
sql/sql_lex.h:
--New LEX::context_analysis_only field
sql/sql_parse.cc:
--removed unnecessary code
sql/sql_prepare.cc:
--removed unnecessary code
--added LEX::context_analysis_only analysis intialization/cleanup
sql/sql_select.cc:
--refactored context analysis checks
sql/sql_show.cc:
--added LEX::context_analysis_only analysis intialization/cleanup
sql/sql_view.cc:
--added LEX::context_analysis_only analysis intialization/cleanup
create_sort_index() function overwrites original JOIN_TAB::type field.
At re-execution of subquery overwritten JOIN_TAB::type(JT_ALL) is
used instead of JT_FT. It misleads test_if_skip_sort_order() and
the function tries to find suitable key for the order that should
not be allowed for FULLTEXT(JT_FT) table.
The fix is to restore JOIN_TAB strucures for subselect on re-execution
for EXPLAIN.
Additional fix:
Update TABLE::maybe_null field which
affects list_contains_unique_index() behaviour as it
could have the value(maybe_null==TRUE) based on the
assumption that this join is outer
(see setup_table_map() func).
mysql-test/r/explain.result:
test case
mysql-test/t/explain.test:
test case
sql/item_subselect.cc:
Make subquery uncacheable in case of EXPLAIN. It allows to keep
original JOIN_TAB::type(see JOIN::save_join_tab) and restore it
on re-execution.
sql/sql_select.cc:
-restore JOIN_TAB strucures for subselect on re-execution for EXPLAIN
-Update TABLE::maybe_null field as it could have
the value(maybe_null==TRUE) based on the assumption
that this join is outer(see setup_table_map() func).
This change is not related to the crash problem but
affects EXPLAIN results in the test case.
The crash happens because original join table is replaced with temporary table
at execution stage and later we attempt to use this temporary table in
select_describe. It might happen that
Item_subselect::update_used_tables() method which sets const_item flag
is not called by some reasons (no where/having conditon in subquery for example).
It prevents JOIN::join_tmp creation and breaks original join.
The fix is to call ::update_used_tables() before ::const_item() check.
mysql-test/r/ps.result:
test case
mysql-test/t/ps.test:
test case
sql/item_subselect.cc:
call ::update_used_tables() before ::const_item() check.
to 5.5 (removed one test case as it is no longer valid).
mysql-test/r/select.result:
Removed a part of the test case for bug#48291 since it is not
valid anymore. The comments for the removed part were actually
describing a side-effect from the problem addressed by the
addendum patch for bug #54190.
mysql-test/t/select.test:
Removed a part of the test case for bug#48291 since it is not
valid anymore. The comments for the removed part were actually
describing a side-effect from the problem addressed by the
addendum patch for bug #54190.
result
Row subqueries producing no rows were not handled as UNKNOWN
values in row comparison expressions.
That was a result of the following two problems:
1. Item_singlerow_subselect did not mark the resulting row
value as NULL/UNKNOWN when no rows were produced.
2. Arg_comparator::compare_row() did not take into account that
a whole argument may be NULL rather than just individual scalar
values.
Before bug#34384 was fixed, the above problems were hidden
because an uninitialized (i.e. without any stored value) cached
object would appear as NULL for scalar values in a row subquery
returning an empty result. After the fix
Arg_comparator::compare_row() would try to evaluate
uninitialized cached objects.
Fixed by removing the aforementioned problems.
mysql-test/r/row.result:
Added a test case for bug #54190.
mysql-test/r/subselect.result:
Updated the result for a test relying on wrong behavior.
mysql-test/t/row.test:
Added a test case for bug #54190.
sql/item_cmpfunc.cc:
If either of the argument rows is NULL, return NULL as the
result of comparison.
sql/item_subselect.cc:
Adjust null_value for Item_singlerow_subselect depending on
whether a row has been produced by the row subquery.
The EXISTS transformation has additional switches to catch the known corner
cases that appear when transforming an IN predicate into EXISTS. Guarded
conditions are used which are deactivated when a NULL value is seen in the
outer expression's row. When the inner query block supplies NULL values,
however, they are filtered out because no distinction is made between the
guarded conditions; guarded NOT x IS NULL conditions in the HAVING clause that
filter out NULL values cannot be de-activated in isolation from those that
match values or from the outer expression or NULL's.
The above problem is handled by making the guarded conditions remember whether
they have rejected a NULL value or not, and index access methods are taking
this into account as well.
The bug consisted of
1) Not resetting the property for every nested loop iteration on the inner
query's result.
2) Not propagating the NULL result properly from inner query to IN optimizer.
3) A hack that may or may not have been needed at some point. According to a
comment it was aimed to fix#2 by returning NULL when FALSE was actually
the result. This caused failures when #2 was properly fixed. The hack is
now removed.
The fix resolves all three points.
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.
We should disable const subselect item evaluation because
subselect transformation does not happen in view_prepare_mode
and thus val_...() methods can not be called.
mysql-test/r/ctype_ucs.result:
test case
mysql-test/r/view.result:
test case
mysql-test/t/ctype_ucs.test:
test case
mysql-test/t/view.test:
test case
sql/item.cc:
disabled const subselect item evaluation in
view prepare mode.
sql/item_subselect.cc:
added Item_subselect::safe_charset_converter which
prevents const item evaluation in view prepare mode.
sql/item_subselect.h:
added Item_subselect::safe_charset_converter which
prevents const item evaluation in view prepare mode.
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
Conflicts:
Text conflict in client/mysqlbinlog.cc
Text conflict in mysql-test/Makefile.am
Text conflict in mysql-test/collections/default.daily
Text conflict in mysql-test/r/mysqlbinlog_row_innodb.result
Text conflict in mysql-test/suite/rpl/r/rpl_typeconv_innodb.result
Text conflict in mysql-test/suite/rpl/t/rpl_get_master_version_and_clock.test
Text conflict in mysql-test/suite/rpl/t/rpl_row_create_table.test
Text conflict in mysql-test/suite/rpl/t/rpl_slave_skip.test
Text conflict in mysql-test/suite/rpl/t/rpl_typeconv_innodb.test
Text conflict in mysys/charset.c
Text conflict in sql/field.cc
Text conflict in sql/field.h
Text conflict in sql/item.h
Text conflict in sql/item_func.cc
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/mysqld.cc
Text conflict in sql/rpl_utility.cc
Text conflict in sql/rpl_utility.h
Text conflict in sql/set_var.cc
Text conflict in sql/share/Makefile.am
Text conflict in sql/sql_delete.cc
Text conflict in sql/sql_plugin.cc
Text conflict in sql/sql_select.cc
Text conflict in sql/sql_table.cc
Text conflict in storage/example/ha_example.h
Text conflict in storage/federated/ha_federated.cc
Text conflict in storage/myisammrg/ha_myisammrg.cc
Text conflict in storage/myisammrg/myrg_open.c
Conflicts:
Text conflict in mysql-test/r/partition_innodb.result
Text conflict in sql/field.h
Text conflict in sql/item.h
Text conflict in sql/item_cmpfunc.h
Text conflict in sql/item_sum.h
Text conflict in sql/log_event_old.cc
Text conflict in sql/protocol.cc
Text conflict in sql/sql_select.cc
Text conflict in sql/sql_yacc.yy
The problem was that killing a query during the optimization
phase of a subselect would lead to crashes. The root of the
problem is that the subselect execution engine ignores failures
(eg: killed) during the optimization phase (JOIN::optimize),
leading to a crash once the subquery is executed due to
partially initialized structures (in this case a join tab).
The optimal solution would be to cleanup certain optimizer
structures if the optimization phase fails, but currently
there is no infrastructure to properly to track and cleanup
the structures. To workaround the whole problem one somewhat
good solution is to avoid executing a subselect if the query
has been killed. Cutting short any problems caused by failures
during the optimization phase.
sql/item_subselect.cc:
Do not execute a subselect if the session or query has been killed.
If an outer query is broken, a subquery might not even get set up.
EXPLAIN EXTENDED did not expect this and merrily tried to de-ref all
of the half-setup info.
We now catch this case and print as much as we have, as it doesn't cost us
anything (doesn't make regular execution slower).
backport from 5.1
mysql-test/r/explain.result:
Show that EXPLAIN EXTENDED with subquery and illegal out query doesn't crash.
Show also that SHOW WARNINGS will render an additional Note in the hope of
being, well, helpful.
mysql-test/t/explain.test:
If we have only half a query for EXPLAIN EXTENDED to print (i.e.,
incomplete subquery info as outer query is illegal), we should
provide the user with as much info as we easily can if they ask
for it. What we should not do is crash when they come asking for
help, that violates etiquette in some countries.
sql/item_subselect.cc:
If the sub-query's actually set up, print it. Otherwise, elide.
