Fields belonging to views in general cannot be substituted for
equal items, in particular for constants, because all references
to a view field refer to the same Item_field object while they
could be used in different OR parts of the where condition and
belong to different equivalence classes (to different Item_equals).
That's why substitution for equal items in any context is allowed
only in place of Item_direct_view_ref objects, but not in place of
Item_fields these objects refer to.
Due to some erroneous code in the patch for bug 717577 substitution
for view fields were allowed in some context.This could lead
to wrong results returned by queries using views.
The fix prohibits substitution of view fields for equal items
in any context.
The patch also changes slightly the compile method for the Item_func
class. Now if the analyze method returns NULL in his parameter the
compile method is not called for the arguments of the function
at all. A similar change was made for the Item_ref class.
When a view is merged into a select all the depended_from fields
pointing to the select of the view should have been corrected to
point to the select where the view is used. It was not done yet.
This could lead to wrong results returned by queries such as
one from the test case for bug 33389.
Correction of outer references required walking through all items
of the proccesed qurery. To avoid this the following solution was
implemented.
Each select now contains a pointer to the select it is merged into
(if there is any). Such pointers allow to get the corrected value
of depended_from on the fly. The function Item_ident::get_depended_from
was introduced for this purpose.
Fixed alias bug when compiling with gcc 4.2.4 that caused subselect.test to fail
sql/item.cc:
Removed alias warnings by changing type from char * to const char*
sql/item.h:
Removed alias warnings by changing type from char * to const char*
sql/item_subselect.cc:
Fixed alias bug when compiling with gcc 4.2.4 that caused subselect.test to fail
sql/sql_string.h:
Removed alias warnings by changing type from char * to const char*
storage/heap/hp_test2.c:
Removed SAFEMALLOC to get rid of compiler error
Fixed test case as we can't anymore use heap_rlast() on a HASH key entry.
Resolved all conflicts, bad merges and fixed a few minor bugs in the code.
Commented out the queries from multi_update, view, subselect_sj, func_str,
derived_view, view_grant that failed either with crashes in ps-protocol or
with wrong results.
The failures are clear indications of some bugs in the code and these bugs
are to be fixed.
Bugs fixed:
- Added automatic detection of unsigned arguments to COLUMN_CREATE()
- If string length is not know for COLUMN_GET() use MAX_DYNAMIC_COLUMN_LENGTH instead of MAX_FIELD_BLOBLENGTH
- null_value flag was not propery reset for COLUMN_LIST() and COLUMN_CREATE() which could lead to crashes later:
- lp:778905 Assertion `value->year <= 9999' failed in dynamic_column_date_store
- lp:778912 Assertion `field_pos < field_count' failed in Protocol_text::store in maria-5.3-mwl34
include/ma_dyncol.h:
Added define for max dynamic column length.
mysql-test/r/cast.result:
Added test of cast big unsigned int to signed (this test case was missing)
mysql-test/r/dyncol.result:
Added tests from reported bugs
Added testing of automatic store of signed/unsigned integers
mysql-test/t/cast.test:
Added test of cast big unsigned int to signed (this test case was missing)
mysql-test/t/dyncol.test:
Added tests from reported bugs
Added testing of automatic store of signed/unsigned integers
sql/item.cc:
Added assert to catch cases where null_value is not set properly
sql/item_strfunc.cc:
Added automatic detection of unsigned arguments to COLUMN_CREATE()
COLUMN_GET() returned wrong value for illegal strings which lead to assert later
null_value flag was not propery reset for COLUMN_LIST() and COLUMN_CREATE() which could lead to crashes later.
sql/item_strfunc.h:
If string length is not know for COLUMN_GET() use MAX_DYNAMIC_COLUMN_LENGTH
- COLUMN_CREATE(column_nr, value, [column_nr,value]...)
- COLUMN_ADD(blob,column_nr, value, column_nr,value]...)
- COLUMN_DELETE(blob, column_nr, column_nr...)
- COLUMN_EXISTS(blob, column_nr)
- COLUMN_LIST(blob, column_nr)
- COLUMN_GET(string, column_nr AS type)
Added cast(X as DOUBLE) and cast(x as INT)
Better warning and error messages for wrong cast's
Created some sub functions to simplify and reuse code.
Added a lot of conversation functions with error/warnings for what went wrong.
Fixed some issues when casting time to datetime.
Added functions to dynamic strings and Strings to allow one to move a string buffer from dynamic strings to String (to save malloc+ copy)
Added dynamic columns library to libmysqlclient
include/Makefile.am:
Added ma_dyncol.h
include/decimal.h:
Added 'const' to arguments for some functions.
include/my_sys.h:
Added dynstr_reassociate()
include/my_time.h:
Added TIME_SUBSECOND_RANGE
Added double_to_datetime()
Added flag argument to str_to_time()
libmysql/CMakeLists.txt:
Added mysys/ma_dyncol.c
libmysql/Makefile.shared:
Added ma_dyncol
libmysql/libmysql.c:
Added argument to str_to_time()
mysql-test/r/bigint.result:
Better error messages
mysql-test/r/cast.result:
Better warning and error messages
A lot of new cast() tests
mysql-test/r/func_math.result:
Better warning messages
mysql-test/r/func_str.result:
Better warning messages
mysql-test/r/func_time.result:
Better warning messages
mysql-test/r/sp-vars.result:
Better warning messages
mysql-test/r/strict.result:
Better warning messages
New test result
mysql-test/r/type_newdecimal.result:
Better warning messages
mysql-test/r/warnings.result:
Better warning messages
mysql-test/suite/funcs_1/r/innodb_func_view.result:
Updated results after better cast warnings
mysql-test/suite/funcs_1/r/memory_func_view.result:
Updated results after better cast warnings
mysql-test/suite/funcs_1/r/myisam_func_view.result:
Updated results after better cast warnings
mysql-test/suite/optimizer_unfixed_bugs/t/bug43448.test:
Added begin...commit to speed up test.
mysql-test/suite/parts/inc/part_supported_sql_funcs_delete.inc:
Added begin...commit to speed up test.
mysql-test/suite/parts/inc/partition_supported_sql_funcs.inc:
Added begin...commit to speed up test.
mysql-test/suite/parts/r/part_supported_sql_func_innodb.result:
Added begin...commit to speed up test.
mysql-test/suite/parts/r/part_supported_sql_func_myisam.result:
Added begin...commit to speed up test.
mysql-test/suite/parts/r/rpl_partition.result:
Added begin...commit to speed up test.
mysql-test/suite/parts/t/part_supported_sql_func_innodb.test:
Removed duplicated --big_test
mysql-test/suite/parts/t/rpl_partition.test:
Added begin...commit to speed up test.
mysql-test/suite/pbxt/r/cast.result:
Updated results after better cast warnings
mysql-test/suite/pbxt/r/func_str.result:
Updated results after better cast warnings
mysql-test/suite/pbxt/r/type_newdecimal.result:
Updated results after better cast warnings
mysql-test/suite/rpl/r/rpl_innodb_bug28430.result:
Added begin...commit to speed up test.
mysql-test/suite/rpl/t/rpl_innodb_bug28430.test:
Added begin...commit to speed up test.
mysql-test/suite/vcol/r/vcol_supported_sql_funcs_innodb.result:
More warnings
mysql-test/suite/vcol/r/vcol_supported_sql_funcs_myisam.result:
More warnings
mysql-test/t/cast.test:
A lot of new cast() tests
mysql-test/t/strict.test:
Added new test
mysys/CMakeLists.txt:
Added ma_dyncol.c
mysys/Makefile.am:
Added ma_dyncol.c
mysys/string.c:
Added dynstr_reassociate() to move a buffer from dynamic_strings to some other allocator
sql-common/my_time.c:
Added 'fuzzydate' flag to str_to_time()
Added support for microseconds to my_time_to_str() and my_datetime_to_str()
Reset second_parts in number_to_datetime()
Added double_to_datetime()
sql/field.cc:
Added double_to_longlong() and truncate_double() to simplify and reuse code
sql/field.h:
New prototypes
sql/item.cc:
Changed Item::get_date(MYSQL_TIME *ltime,uint fuzzydate) to be aware of type of argument.
(Needed to make it microsecond safe and get better warnings).
Updated call to str_to_time_with_warn()
sql/item.h:
Added struct st_dyncall_create_def used by dynamic columns
Added virtual bool dynamic_result() to tell if type of argument may change over calls.
sql/item_cmpfunc.cc:
Added Item_func_dyncol_exists()
sql/item_cmpfunc.h:
Added class Item_func_dyncol_exists
sql/item_create.cc:
Added get_length_and_scale() to simplify other functions
Simplified and extended create_func_cast()
Added support for cast(X as double(X,Y))
Added functions to create dynamic column functions.
sql/item_create.h:
Added prototypes
sql/item_func.cc:
Extended cast functions Item_func_signed() and Item_func_unsigned() to work with dynamic types
Added Item_double_typecast()
sql/item_func.h:
Added class Item_double_typecast()
sql/item_strfunc.cc:
Added functions for COLUMN_CREATE(), COLUMN_ADD(), COLUMN_GET() and COLUMN_LIST()
sql/item_strfunc.h:
Added classes for COLUMN_CREATE(), COLUMN_ADD(), COLUMN_GET() and COLUMN_LIST()
sql/item_timefunc.cc:
Added flag argument to str_to_time_with_warn()
Updated Item_char_typecast() to handle result type that may change between calls (for dynamic columns)
Added Item_time_typecast::get_date() to ensure that we cast a datetime to time properly.
sql/item_timefunc.h:
Added get_date() to Item_time_typecast() to allow proper results for casting time to datetime
sql/lex.h:
Added new SQL function names
sql/my_decimal.cc:
Added 'const' to some arguments.
Better error message in case of errors (we now print out the wrong value)
Added my_decimal2int()
sql/my_decimal.h:
Moved some constants to my_decimal_limits.h
Updated prototypes.
Made my_decimal2int() a function as it's rather long (no reason to have it inline)
Added decimal2my_decimal() function.
sql/mysql_priv.h:
Prototypes for new functions
sql/share/errmsg.txt:
New error messages for wrong casts and dynamic columns
sql/sql_acl.cc:
Fixed indentation
sql/sql_base.cc:
Added dynamic_column_error_message()
sql/sql_string.h:
Added reassociate() to move a buffer to be owned by String object.
sql/sql_yacc.yy:
Added syntax for COLUMN_ functions.
sql/time.cc:
Updated str_to_datetime_with_warn() flag argument to same type as other functions
Added conversion flag to str_to_time_with_warn() (Similar to all datetime functions)
Added conversion functions with warnings: double_to_datetime_with_warn() and decimal_to_datetime_with_warn()
strings/decimal.c:
Added 'const' to arguments for some functions.
unittest/mysys/Makefile.am:
Added test for dynamic columns code
Both these two bugs happened due to the following problem.
When a view column is referenced in the query an Item_direct_view_ref
object is created that is refers to the Item_field for the column.
All references to the same view column refer to the same Item_field.
Different references can belong to different AND/OR levels and,
as a result, can be included in different Item_equal object.
These Item_equal objects may include different constant objects.
If these constant objects are substituted for the Item_field created
for a view column we have a conflict situation when the second
substitution annuls the first substitution. This leads to
wrong result sets returned by the query. Bug #724942 demonstrates
such an erroneous behaviour.
Test case of the bug #717577 produces wrong result sets because best
equal fields of the multiple equalities built for different OR levels
of the WHERE condition differs. The subsitution for the best equal field
in the second OR branch overwrites the the substitution made for the
first branch.
To avoid such conflicts we have to substitute for the references
to the view columns rather than for the underlying field items.
To make such substitutions possible we have to include into
multiple equalities references to view columns rather than
field items created for such columns.
This patch modifies the Item_equal class to include references
to view columns into multiple equality objects. It also performs
a clean up of the class methods and adds more comments. The methods
of the Item_direct_view_ref class that assist substitutions for
references to view columns has been also added by this patch.
Select from a view with the underlying HAVING clause failed with a
message: "1356: View '...' references invalid table(s) or column(s)
or function(s) or definer/invoker of view lack rights to use them"
The bug is a regression of the fix for bug 11750328 - 40825 (similar
case, but the HAVING cause references an aliased field).
In the old fix for bug 40825 the Item_field::name_length value has
been used in place of the real length of Item_field::name. However,
in some cases Item_field::name_length is not in sync with the
actual name length (TODO: combine name and name_length into a
solid String field).
The Item_ref::print() method has been modified to calculate actual
name length every time.
mysql-test/r/view.result:
Test case for bug #11829681
mysql-test/t/view.test:
Test case for bug #11829681
sql/item.cc:
Bug #11829681 - 60295: ERROR 1356 ON VIEW THAT EXECUTES FINE AS A QUERY
The Item_ref::print() method has been modified to calculate actual
name length every time.
sql/item.h:
Minor commentary.
- Auto-merge with 5.3 main.
- Changed the test for LP BUG#719198 so that
an two more queries were added, and removed a
query that produces a wrong result due to an
unrelated problem. The wrong result is submitted
as a separate bug.
In the string context the MIN() and MAX() functions don't take
into account the unsignedness of the UNSIGNED BIGINT argument
column.
I.e.:
CREATE TABLE t1 (a BIGINT UNSIGNED);
INSERT INTO t1 VALUES (18446668621106209655);
SELECT CONCAT(MAX(a)) FROM t1;
returns -75452603341961.
mysql-test/r/func_group.result:
Test case for bug #11766094.
mysql-test/t/func_group.test:
Test case for bug #11766094.
sql/item.cc:
Bug #11766094 - 59132: MIN() AND MAX() REMOVE UNSIGNEDNESS
The Item_cache_int::val_str() method has been modified to
take into account the unsigned_flag value when converting
data to string.
sql/item.cc:
If a item_ref is referenced by name, we have to reset it's ref in item_ref::cleanup() as the reference may be to a memory that is freed.
This happens at least when you have 'HAVING MAX()' in a sub query and you execute 'cond_having->print()' which tries to access items before fix fields.
sql/item.h:
Added 'reference_trough_name' as a marker for Item_ref that needs to have ref reset during cleanup
Fixed memory leak from HEAP tables that was not deleted properly
BUILD/compile-alpha-ccc:
Use g++ instead of gcc for linking
BUILD/compile-alpha-debug:
Use g++ instead of gcc for linking
BUILD/compile-pentium-pgcc:
Use g++ instead of gcc for linking
BUILD/compile-solaris-sparc:
Use g++ instead of gcc for linking
BUILD/compile-solaris-sparc-debug:
Use g++ instead of gcc for linking
BUILD/compile-solaris-sparc-purify:
Use g++ instead of gcc for linking
sql/item.cc:
Safety fixes for expr_cache
Call Item_result:field::cleanup() in Item_cache_wrapper::cleanup()
More DBUG_PRINT
sql/sql_base.cc:
Simple optimization for setup_wild
More DBUG_PRINT
sql/sql_expression_cache.cc:
Added header
Removed not needed initialization
sql/sql_lex.cc:
More DBUG_PRINT
sql/sql_select.cc:
More DBUG_PRINT
Fixed memory leak from HEAP tables that was not deleted properly
storage/heap/hp_create.c:
More DBUG_PRINT
Valgrind warning happens due to missing NULL value check in
Item::get_date. The fix is to add this check.
mysql-test/r/func_time.result:
test case
mysql-test/t/func_time.test:
test case
sql/item.cc:
added check for NULL value
Analysis:
A query with implicit grouping is one with aggregate functions and
no GROUP BY clause. MariaDB inherits from MySQL an SQL extenstion
that allows mixing aggregate functions with non-aggregate fields.
If a query with such mixed select clause produces an empty result
set, the meaning of aggregate functions is well defined - either
NULL (MIN, MAX, etc.), or 0 (count(*)). However the non-aggregated
fields must also have some value, and the only reasonable value in
the case of empty result is NULL.
The cause of the many wrong results was that if a field is declared
as non-nullable (e.g. because it is a PK or NOT NULL), the semantic
analysis and the optimization phases treat this field as non-nullable,
and generate all related query plan elements based on this assumption.
Later during execution, these incorrectly configured/generated query
plan elements result in a wrong result because the selected fields
are not null due to the not-null assumption during optimization.
Solution:
Detect before the context analysys phase that a query uses implicit
grouping with mixed aggregates/non-aggregates, and set all fields
as nullable. The parser already walks the SELECT clause, and
already sets Item::with_sum_func for Items that reference aggreagate
functions. The patch adds a symmetric Item::with_field so that all
Items that reference an Item_field are marked during their
construction at parse time in the same way as with aggregate function
use.
The problem was that server didn't check resulting size of prepared
statement argument which was set using mysql_send_long_data() API.
By calling mysql_send_long_data() several times it was possible
to create overly big string and thus force server to allocate
memory for it. There was no way to limit this allocation.
The solution is to add check for size of result string against
value of max_long_data_size start-up parameter. When intermediate
string exceeds max_long_data_size value an appropriate error message
is emitted.
We can't use existing max_allowed_packet parameter for this purpose
since its value is limited by 1GB and therefore using it as a limit
for data set through mysql_send_long_data() API would have been an
incompatible change. Newly introduced max_long_data_size parameter
gets value from max_allowed_packet parameter unless its value is
specified explicitly. This new parameter is marked as deprecated
and will be eventually replaced by max_allowed_packet parameter.
Value of max_long_data_size parameter can be set only at server
startup.
mysql-test/t/variables.test:
Added checking for new start-up parameter max_long_data_size.
sql/item.cc:
Added call to my_message() when accumulated string exceeds
max_long_data_size value. my_message() calls error handler
that was installed in mysql_stmt_get_longdata before call
to Item_param::set_longdata.
The error handler then sets state, last_error and last_errno
fields for current statement to values which correspond to
error which was caught.
sql/mysql_priv.h:
Added max_long_data_size variable declaration.
sql/mysqld.cc:
Added support for start-up parameter 'max_long_data_size'.
This parameter limits size of data which can be sent from
client to server using mysql_send_long_data() API.
sql/set_var.cc:
Added variable 'max_long_data_size' into list of variables
displayed by command 'show variables'.
sql/sql_prepare.cc:
Added error handler class Set_longdata_error_handler.
This handler is used to catch any errors that can be
generated during execution of Item_param::set_longdata().
Source code snippet that makes checking for statement's state
during statement execution is moved from Prepared_statement::execute()
to Prepared_statement::execute_loop() in order not to call
set_parameters() when statement has failed during
set_long_data() execution. If this hadn't been done
the call to set_parameters() would have failed.
tests/mysql_client_test.c:
A testcase for the bug #56976 was added.
Changed some String.ptr() -> String.c_ptr() for String that are not guaranteed to end with \0
Removed some c_ptr() usage from parameters to functions that takes ptr & length
Use preallocate buffers to avoid calling malloc() for most operations.
sql/event_db_repository.cc:
alias is now a String
sql/event_scheduler.cc:
c_ptr -> c_ptr_safe() to avoid warnings from valgrind.
sql/events.cc:
c_ptr -> c_ptr_safe() to avoid warnings from valgrind.
c_ptr -> ptr() as function takes ptr & length
sql/field.cc:
alias is now a String
sql/field.h:
alias is now a String
sql/ha_partition.cc:
alias is now a String
sql/handler.cc:
alias is now a String
ptr() -> c_ptr() as string is not guaranteed to be \0 terminated
sql/item.cc:
Store error parameter in separarte buffer to ensure correct error message
sql/item_func.cc:
ptr() -> c_ptr_safe() as string is not guaranteed to be \0 terminated
sql/item_sum.h:
Use my_strtod() instead of my_atof() to not have to make string \0 terminated
sql/lock.cc:
alias is now a String
sql/log.cc:
c_ptr() -> ptr() as function takes ptr & length
sql/log_event.cc:
c_ptr_quick() -> ptr() as we only want to get the pointer to String buffer
sql/opt_range.cc:
ptr() -> c_ptr() as string is not guaranteed to be \0 terminated
sql/opt_table_elimination.cc:
alias is now a String
sql/set_var.cc:
ptr() -> c_ptr() as string is not guaranteed to be \0 terminated
c_ptr() -> c_ptr_safe() to avoid warnings from valgrind.
c_ptr() -> ptr() as function takes ptr & length
Simplify some code.
sql/sp.cc:
c_ptr() -> ptr() as function takes ptr & length
sql/sp_rcontext.cc:
alias is now a String
sql/sql_base.cc:
alias is now a String.
Here we win a realloc() for most alias usage.
sql/sql_class.cc:
Use size descriptor for printf() to avoid accessing bytes outside of buffer
sql/sql_insert.cc:
Change allocation of TABLE as it's now contains a String
_ptr() -> ptr() as function takes ptr & length
sql/sql_load.cc:
Use preallocate buffers to avoid calling malloc() for most operations.
sql/sql_parse.cc:
Use c_ptr_safe() to ensure string is \0 terminated.
sql/sql_plugin.cc:
c_ptr_quick() -> ptr() as function takes ptr & length
sql/sql_select.cc:
alias is now a String
sql/sql_show.cc:
alias is now a String
sql/sql_string.h:
Added move() function to change who owns the string (owner does the free)
sql/sql_table.cc:
alias is now a String
c_ptr() -> c_ptr_safe() to avoid warnings from valgrind.
sql/sql_test.cc:
c_ptr() -> c_ptr_safe() to avoid warnings from valgrind.
alias is now a String
sql/sql_trigger.cc:
c_ptr() -> c_ptr_safe() to avoid warnings from valgrind.
Use field->init() to setup pointers to alias.
sql/sql_update.cc:
alias is now a String
sql/sql_view.cc:
ptr() -> c_ptr_safe() as string is not guaranteed to be \0 terminated
sql/sql_yacc.yy:
r() -> c_ptr() as string is not guaranteed to be \0 terminated
sql/table.cc:
alias is now a String
sql/table.h:
alias is now a String
storage/federatedx/ha_federatedx.cc:
Remove extra 1 byte alloc that is automaticly done by strmake()
Ensure that error message ends with \0
storage/maria/ha_maria.cc:
alias is now a String
storage/myisam/ha_myisam.cc:
alias is now a String
- Fixed some issues with partitions and connection_string, which also fixed lp:716890 "Pre- and post-recovery crash in Aria"
- Fixed wrong assert in Aria
Now need to merge with latest xtradb before pushing
sql/ha_partition.cc:
Ensure that m_ordered_rec_buffer is not freed before close.
sql/mysqld.cc:
Changed to use opt_stack_trace instead of opt_pstack.
Removed references to pstack
sql/partition_element.h:
Ensure that connect_string is initialized
storage/maria/ma_key_recover.c:
Fixed wrong assert
The patch fixed the following optimizer defect: when performing
substitution for best equal fields into where conditions to be
able to do their evaluations as soon as possible the optimizer
skipped conditions over views. That could lead to suboptimal
execution of queries that used views.
Slightly changed the test case to demonstrate the performance
improvements if this fix.
sql/item.cc:
Wrapper added.
sql/item.h:
Wrapper added.
sql/mysql_priv.h:
Wrap function added.
sql/sql_base.cc:
Wrap function added.
Fix of problem with WHERE consist of alone outer reference field by wrapping it.
sql/sql_select.cc:
Fix of problem with HAVING consist of alone outer reference field by wrapping it.
Made sure that the optimal fields are used by TABLE_REF objects
when building index access keys to joined tables.
Fixed a bug in the template function that sorts the elements of
a list using the bubble sort algorithm. The bug caused poor
performance of the function. Also added an optimization that
skips comparison with the most heavy elements that has been
already properly placed in the list.
Made the comparison of the fields belonging to the same Item_equal
more granular: fields belonging to the same table are also ordered
according to some rules.
Item_sum_max/Item_sum_min incorrectly set null_value flag and
attempt to get result in parent functions leads to crash.
This happens due to double evaluation of the function argumet.
First evaluation happens in the comparator and second one
happens in Item_cache::cache_value().
The fix is to introduce new Item_cache object which
holds result of the argument and use this cached value
as an argument of the comparator.
mysql-test/r/func_group.result:
test case
mysql-test/t/func_group.test:
test case
sql/item.cc:
added assertion that ether we have some result or result is NULL.
sql/item_sum.cc:
introduce new Item_cache object which
holds result of the argument and use this cached value
as an argument of the comparator.
sql/item_sum.h:
introduce new Item_cache object which
holds result of the argument and use this cached value
as an argument of the comparator.
--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
- Fixed problem with oqgraph and 'make dist'
Note that after this merge we have a problem show in join_outer where we examine too many rows in one specific case (related to BUG#57024).
This will be fixed when mwl#128 is merged into 5.3.
- Changed TABLE->alias to String to get fewer reallocs when alias are used.
- Preallocate some buffers
Changed some String->c_ptr() -> String->ptr() when \0 is not needed.
Fixed wrong usage of String->ptr() when we need a \0 terminated string.
Use my_strtod() instead of my_atof() to avoid having to add \0 to string.
c_ptr() -> c_ptr_safe() to avoid warnings from valgrind.
zr
sql/event_db_repository.cc:
Update usage of TABLE->alias
sql/event_scheduler.cc:
c_ptr() -> c_ptr_safe()
sql/events.cc:
c_ptr() -> ptr() as \0 was not needed
sql/field.cc:
Update usage of TABLE->alias
sql/field.h:
Update usage of TABLE->alias
sql/ha_partition.cc:
Update usage of TABLE->alias
sql/handler.cc:
Update usage of TABLE->alias
Fixed wrong usage of str.ptr()
sql/item.cc:
Fixed error where code wrongly assumed string was \0 terminated.
sql/item_func.cc:
c_ptr() -> c_ptr_safe()
Update usage of TABLE->alias
sql/item_sum.h:
Use my_strtod() instead of my_atof() to avoid having to add \0 to string
sql/lock.cc:
Update usage of TABLE->alias
sql/log.cc:
c_ptr() -> ptr() as \0 was not needed
sql/log_event.cc:
c_ptr_quick() -> ptr() as \0 was not needed
sql/opt_range.cc:
ptr() -> c_ptr() as \0 is needed
sql/opt_subselect.cc:
Update usage of TABLE->alias
sql/opt_table_elimination.cc:
Update usage of TABLE->alias
sql/set_var.cc:
ptr() -> c_ptr() as \0 is needed
c_ptr() -> c_ptr_safe()
sql/sp.cc:
c_ptr() -> ptr() as \0 was not needed
sql/sp_rcontext.cc:
Update usage of TABLE->alias
sql/sql_base.cc:
Preallocate buffers
Update usage of TABLE->alias
sql/sql_class.cc:
Fix arguments to sprintf() to work even if string is not \0 terminated
sql/sql_insert.cc:
Update usage of TABLE->alias
c_ptr() -> ptr() as \0 was not needed
sql/sql_load.cc:
Preallocate buffers
Trivial optimizations
sql/sql_parse.cc:
Trivial optimization
sql/sql_plugin.cc:
c_ptr() -> ptr() as \0 was not needed
sql/sql_select.cc:
Update usage of TABLE->alias
sql/sql_show.cc:
Update usage of TABLE->alias
sql/sql_string.h:
Added move() function to move allocated memory from one object to another.
sql/sql_table.cc:
Update usage of TABLE->alias
c_ptr() -> c_ptr_safe()
sql/sql_test.cc:
ptr() -> c_ptr_safe()
sql/sql_trigger.cc:
Update usage of TABLE->alias
c_ptr() -> c_ptr_safe()
sql/sql_update.cc:
Update usage of TABLE->alias
sql/sql_view.cc:
ptr() -> c_ptr_safe()
sql/sql_yacc.yy:
ptr() -> c_ptr()
sql/table.cc:
Update usage of TABLE->alias
sql/table.h:
Changed TABLE->alias to String to get fewer reallocs when alias are used.
storage/federatedx/ha_federatedx.cc:
Use c_ptr_safe() to ensure strings are \0 terminated.
storage/maria/ha_maria.cc:
Update usage of TABLE->alias
storage/myisam/ha_myisam.cc:
Update usage of TABLE->alias
storage/xtradb/row/row0sel.c:
Ensure that null bits in record are properly reset.
(Old code didn't work as row_search_for_mysql() can be called twice while reading fields from one row.
Problem: crash in Item_float constructor on DBUG_ASSERT due
to not null-terminated string parameter.
Fix: making Item_float::Item_float non-null-termintated parameter safe:
- Using temporary buffer when generating error
modified:
@ mysql-test/r/xml.result
@ mysql-test/t/xml.test
@ sql/item.cc
