int join_read_key(JOIN_TAB*)
The eq_ref access method TABLE_REF (accessed through
JOIN_TAB) to save state and to track if this is the
first row it finds or not.
This state was not reset on subquery re-execution
causing an assert.
Fixed by resetting the state before the subquery
re-execution.
Constant expressions in WHERE/HAVING/ON clauses aren't cached and evaluated
for each row. This causes slowdown of query execution especially if constant
UDF/SP function are used.
Now WHERE/HAVING/ON expressions are analyzed in the top-bottom direction with
help of the compile function. When analyzer meets a constant item it
sets a flag for the tree transformer to cache the item and doesn't allow tree
walker to go deeper. Thus, the topmost item of a constant expression if
cached. This is done after all other optimizations were applied to
WHERE/HAVING/ON expressions
A helper function called cache_const_exprs is added to the JOIN class.
It calls compile method with caching analyzer and transformer on WHERE,
HAVING, ON expressions if they're present.
The cache_const_expr_analyzer and cache_const_expr_transformer functions are
added to the Item class. The first one check if the item can be cached and
the second caches it if so.
A new Item_cache_datetime class is derived from the Item_cache class.
It caches both int and string values of the underlying item independently to
avoid DATETIME aware int-to-string conversion. Thus it completely relies on
the ability of the underlying item to correctly convert DATETIME value from
int to string and vice versa.
mysql-next-mr-bugfixing.
Bug no 32858 was fixed in two different ways in what was
then called mysql 5.1 and 6.0. The fix in 6.0 was very
different since bugfix no 33204 was present. Furthermore,
the two fixes were not compatible. Hence in order to
backport Bug#33204 to the 5.1-based mysql-next-mr-bugfixing,
it was necessary to remove the 5.1 fix of 32858 and apply
the 6.0 version of the fix.
having clause...
The fix for bug 46184 was not very complete. It was not covering
views using temporary tables and multiple tables in a FROM clause.
Fixed by reverting the fix for 46184 and making a more general
check that is checking at the right execution stage and for all
of the non-supported cases.
Now PROCEDURE ANALYZE on non-top level SELECT is also forbidden.
Updated the analyse.test and subselect.test accordingly.
EXPLAIN EXTENDED warning.
Query optimizer searches for the constant tables and optimizes them away. This
means that fields of such tables are substituted for their values and on later
phases they are treated as constants. After this constant tables are removed
from the query execution plan. Nevertheless constant tables were shown in
the EXPLAIN EXTENDED warning thus producing query that might be not an
equivalent of the original query.
Now the print_join function skips all tables that were optimized away from
printing to the EXPLAIN EXTENDED warning. If all tables were optimized away it
produces the 'FROM dual' clause.
The problem was in incorrect handling of predicates involving
NULL as a constant value by the range optimizer.
For example, when creating a SEL_ARG node from a condition of
the form "field < const" (which would normally result in the
"NULL < field < const" SEL_ARG), the special case when "const"
is NULL was not taken into account, so "NULL < field < NULL"
was produced for the "field < NULL" condition.
As a result, SEL_ARG structures of this form could not be
further optimized which in turn could lead to incorrectly
constructed SEL_ARG trees. In particular, code assuming SEL_ARG
structures to always form a sequence of ordered disjoint
intervals could enter an infinite loop under some
circumstances.
Fixed by changing get_mm_leaf() so that for any sargable
predicate except "<=>" involving NULL as a constant, "empty"
SEL_ARG is returned, since such a predicate is always false.
field references
This error requires a combination of factors :
1. An "impossible where" in the outermost SELECT
2. An aggregate in the outermost SELECT
3. A correlated subquery with a WHERE clause that includes an outer
field reference as a top level WHERE sargable predicate
When JOIN::optimize detects an "impossible WHERE" it will bail out
without doing the rest of the work and initializations. It will not
call make_join_statistics() as well. And make_join_statistics fills
in various structures for each table referenced.
When processing the result of the "impossible WHERE" the query must
send a single row of data if there are aggregate functions in it.
In this case the server marks all the aggregates as having received
no rows and calls the relevant Item::val_xxx() method on the SELECT
list. However if this SELECT list happens to contain a correlated
subquery this subquery is evaluated in a normal evaluation mode.
And if this correlated subquery has a reference to a field from the
outermost "impossible where" SELECT the add_key_fields will mistakenly
consider the outer field reference as a "local" field reference when
looking for sargable predicates.
But since the SELECT where the outer field reference refers to is not
completely initialized due to the "impossible WHERE" in this level
we'll get a NULL pointer reference.
Fixed by making a better condition for discovering if a field is "local"
to the SELECT level being processed.
It's not enough to look for OUTER_REF_TABLE_BIT in this case since
for outer references to constant tables the Item_field::used_tables()
will return 0 regardless of whether the field reference is from the
local SELECT or not.
The crash happens because select_union object is used as result set
for queries which have derived tables.
select_union use temporary table as data storage and if
fields count exceeds 10(count of values for procedure ANALYSE())
then we get a crash on fill_record() function.
When during the optimization an item is moved to the upper select
the item's context left unchanged. This caused wrong result in the
PS/SP mode.
The Item_ident::remove_dependence_processor now sets the context
of the select to which the item is moved to.
In a subselect all fields from outer selects are marked as dependent on
selects they are belong to. In some cases optimizer substitutes it for an
equivalent expression. For example "a_field IN (SELECT outer_field)" is
substituted with "a_field = outer_field". As we moved the outer_field to the
upper select it's not really outer anymore. But it was left marked as outer.
If exists an index over a_field optimizer choose wrong execution plan and thus
return wrong result.
Now the Item_in_subselect::single_value_transformer function removes dependent
marking from fields when a subselect is optimized away.
Bug#42003 tests missing the disconnect of connections <> default
second slice
Content:
1. wait_until_count_sessions.inc
- One PB run of a test using this routine failed because
5 seconds timeout were exceeded. Although I have some doubts
if the assigned timeout was really too small, I increase the
value to 10. We waste the additional 5 seconds only if the
tests fails anyway.
- Print the content of the PROCESSLIST if the poll routine fails
2. minor improvements of formatting
3. query_cache_notembedded:
Activate the wait_until_count_sessions.inc routine which was
unfortunately forgotten in the changeset before.
- If missing: add "disconnect <session>"
- If physical disconnect of non "default" sessions is not finished
at test end: add routine which waits till this happened
+ additional improvements
- remove superfluous files created by the test
- replace error numbers by error names
- remove trailing spaces, replace tabs by spaces
- unify writing of bugs within comments
- correct comments
- minor changes of formatting
Fixed tests:
backup
check
compress
grant
information_schema
multi_update
overflow
packet
query_cache_not_embedded
sp-threads
subselect
synchronization
timezone_grant
Item_in_optimizer::is_null() evaluated "NULL IN (SELECT ...)" to NULL regardless of
whether subquery produced any records, this was a documented limitation.
The limitation has been removed (see bugs 8804, 24085, 24127) now
Item_in_optimizer::val_int() correctly handles all cases with NULLs. Make
Item_in_optimizer::is_null() invoke val_int() to return correct values for
"NULL IN (SELECT ...)".
enable uncacheable flag if we update a view with check option
and check option has a subselect, otherwise, the check option
can be evaluated after the subselect was freed as independent
(See full_local in JOIN::join_free())
manually resolved conflicts:
Text conflict in client/mysqltest.c
Contents conflict in mysql-test/include/have_bug25714.inc
Text conflict in mysql-test/include/have_ndbapi_examples.inc
Text conflict in mysql-test/mysql-test-run.pl
Text conflict in mysql-test/suite/parts/inc/partition_check_drop.inc
Text conflict in mysql-test/suite/parts/inc/partition_layout.inc
Text conflict in mysql-test/suite/parts/inc/partition_layout_check1.inc
Text conflict in mysql-test/suite/parts/inc/partition_layout_check2.inc
Text conflict in mysql-test/suite/parts/r/partition_alter1_1_2_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_alter1_1_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_alter1_2_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_alter2_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_alter3_innodb.result
Text conflict in mysql-test/suite/parts/r/partition_alter3_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_basic_innodb.result
Text conflict in mysql-test/suite/parts/r/partition_basic_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_basic_symlink_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_engine_myisam.result
Text conflict in mysql-test/suite/parts/r/partition_syntax_myisam.result
Text conflict in mysql-test/suite/rpl_ndb/t/disabled.def
Text conflict in mysql-test/t/disabled.def
Calling List<Cached_item>::delete_elements for the same list twice
caused a crash of the server in the function JOIN::cleaunup.
Ensured that delete_elements() in JOIN::cleanup would be called only once.
When there is an error executing EXISTS predicates they return NULL as their string
or decimal value but don't set the NULL value flag.
Fixed by returning 0 (as a decimal or a string) on error exectuting the subquery.
Note that we can't return NULL as EXISTS is not supposed to return NULL.
with dependent subqueries
An IN subquery is executed on EXPLAIN when it's not correlated.
If the subquery required a temporary table for its execution
not all the internal structures were restored from pointing to
the items of the temporary table to point back to the items of
the subquery.
Fixed by restoring the ref array when a temp tables were used in
executing the IN subquery during EXPLAIN EXTENDED.
