- Moving some of Database_qualidied_name methods into a new class
Identifier_chain2.
- Changing the data type of the following variables from
Database_qualified_name to Identifier_chain2:
* q_pkg_proc in LEX::call_statement_start()
* q_pkg_func in LEX::make_item_func_call_generic()
Rationale:
The data type of Database_qualified_name::m_db will be changed
to Lex_ident_db soon. So Database_qualified_name won't be able
to store the `pkg.routine` part of `db.pkg.routine` any more,
because `pkg` must not depend on lower-case-table-names.
Before this patch, the code in Item_field::print() used
this convention (described in sql_explain.h:ExplainDataStructureLifetime):
- By default, the table that Item_field refers to is accessible.
- ANALYZE and SHOW {EXPLAIN|ANALYZE} may print Items after some
temporary tables have been dropped. They use
QT_DONT_ACCESS_TMP_TABLES flag. When it is ON, Item_field::print
will not access the table it refers to, if it is a temp.table
The bug was that EXPLAIN statement also may compute subqueries (depending
on subquery context and @@expensive_subquery_limit setting). After the
computation, the subquery calls JOIN::cleanup(true) which drops some of
its temporary tables. Calling Item_field::print() that refer to such table
will cause an access to free'd memory.
In this patch, we take into account that query optimization can compute
a subquery and discard its temporary tables. Item_field::print() now
assumes that any temporary table might have already been dropped.
This means QT_DONT_ACCESS_TMP_TABLES flag is not needed - we imply it is
always present.
But we also make one exception: derived tables are not freed in
JOIN::cleanup() call. They are freed later in close_thread_tables(),
at the same time when regular tables are closed.
Because of that, Item_field::print may assume that temp.tables
representing derived tables are available.
Initial patch by: Rex Jonston
Reviewed by: Monty <monty@mariadb.org>
The problem is that the first execution of the prepared statement makes
a permanent optimization of converting the LEFT JOIN to an INNER JOIN.
This is based on the assumption that all the user parameters (?) are
always constants and that parameters to Item_cond() will not change value
from true and false between different executions.
(The example was using IS NULL, which will change value if parameter
depending on if the parameter is NULL or not).
The fix is to change Item_cond::fix_fields() and
Item_cond::eval_not_null_tables() to not threat user parameters as
constants. This will ensure that we don't do the LEFT_JOIN -> INNER
JOIN conversion that causes problems.
There is also some things that needs to be improved regarding
calculations of not_null_tables_cache as we get a different value for
WHERE 1 or t1.a=1
compared to
WHERE t1.a= or 1
Changes done:
- Mark Item_param with the PARAM flag to be able to quickly check
in Item_cond::eval_not_null_tables() if an item contains a
prepared statement parameter (just like we check for stored procedure
parameters).
- Fixed that Item_cond::not_null_tables_cache is not depending on
order of arguments.
- Don't call item->eval_const_cond() for items that are NOT on the top
level of the WHERE clause. This removed a lot of unnecessary
warnings in the test suite!
- Do not reset not_null_tables_cache for not top level items.
- Simplified Item_cond::fix_fields by calling eval_not_null_tables()
instead of having duplication of all the code in
eval_not_null_tables().
- Return an error if Item_cond::fix_field() generates an error
The old code did generate an error in some cases, but not in all
cases.
- Fixed all handling of the above error in make_cond_for_tables().
The error handling by the callers did not exists before which
could lead to asserts in many different places in the old code).
- All changes in sql_select.cc are just checking the return value of
fix_fields() and make_cond_for_tables() and returning an error
value if fix_fields() returns true or make_cond_for_tables()
returns NULL and is_error() is set.
- Mark Item_cond as const_item if all arguments returns true for
can_eval_in_optimize().
Reviewer: Sergei Petrunia <sergey@mariadb.com>
When printing Item_direct_view_ref the printed field name must be
complemented with the view name/derived table alias.
For example, for "SELECT a FROM (SELECT a FROM t1) q" field `a`
in the select list must be printed as `q`.`a`.
But if the view was merged then the initial `q` does not make sense
any more so field `a` must be printed as `t1`.`a`
Rewrite datetime comparison conditions into sargeable. For example,
YEAR(col) <= val -> col <= YEAR_END(val)
YEAR(col) < val -> col < YEAR_START(val)
YEAR(col) >= val -> col >= YEAR_START(val)
YEAR(col) > val -> col > YEAR_END(val)
YEAR(col) = val -> col BETWEEN YEAR_START(val) AND YEAR_END(val)
Do the same with DATE(col), for example:
DATE(col) <= val -> col <= DAY_END(val)
After such a rewrite index lookup on column "col" can be employed
MDEV-30668 Set function aggregated in outer select used in view definition
This patch fixes two bugs concerning views whose specifications contain
subqueries with set functions aggregated in outer selects.
Due to the first bug those such views that have implicit grouping were
considered as mergeable. This led to wrong result sets for selects from
these views.
Due to the second bug the aggregation select was determined incorrectly and
this led to bogus error messages.
The patch added several test cases for these two bugs and for four other
duplicate bugs.
The patch also enables view-protocol for many other test cases.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
This happens when the subquery marks some index fields as constant
but the fields are still present in GROUP BY
Fixed by checking if the 'constant field' is still part of GROUP BY before
skipping it.
Other things:
- Added Item_field::contains() to make it easier to check if a field
is equal to a Item_field or part of Item_equal.
This bug manifested itself in very rare situations when splitting
optimization was applied to a materialized derived table with group clause
by key over a constant meargeable derived table that was in inner part of
an outer join. In this case the used tables for the key to access the
split table incorrectly was evaluated to a not empty table map.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
