This patch implements the task according to the description:
1. The old code from Item_func_in::fix_length_and_dec() was decomposed
into smaller methods:
- all_items_are_consts()
- compatible_types_scalar_bisection_possible()
- compatible_types_row_bisection_possible()
- fix_in_vector()
- fix_for_scalar_comparison_using_bisection()
- fix_for_scalar_comparison_using_cmp_items()
- fix_for_row_comparison_using_bisection()
- fix_for_row_comparison_using_cmp_items()
The data type dependend pieces where moved as methods to Type_handler.
2. Splits in_datetime into separate:
- in_datetime, for DATETIME and DATE,
- in_time, for TIME
to make the code more symmetric across data types.
Additionally:
- Adds a test func_debug.test to see which calculation strategy
(bisect or no bisect) is chosen to handle IN with various arguments.
- Adds a new helper method (to avoid duplicate code):
cmp_item_rows::prepare_comparators()
- Changes the propotype for cmp_item_row::alloc_comparators(),
to avoid duplicate code, and to use less current_thd.
- Changes "friend" sections in cmp_item_row and in_row from
an exact Item_func_in method to the entire class Item_func_in,
as their internals are now needed in multiple Item_func_in methods.
- Added more comments (e.g. on bisection, on the problem reported in MDEV-11511)
- Removes "Item_result Item_func_opt_neg::m_compare_type" and introduces
"Type_handler_hybrid_field_type Item_func_opt_neg::m_comparator" instead.
- Removes Item_func_between::compare_as_dates, because
the new member m_comparator now contains the precise information
about the data type that is used for comparison, which is important
for TIME vs DATETIME.
- Adds a new method:
Type_handler_hybrid_field_type::aggregate_for_comparison(const Type_handler*),
as a better replacement for item_cmp_type(), which additionally can handle
TIME vs DATE/DATETIME/TIMESTAMP correctly. Additionally, it correctly
handles TIMESTAMP which fixes the problem reported in MDEV-11482.
The old compare_as_dates/find_date_time_item() based code didn't handle
comparison between TIME and TIMESTAMP correctly and erroneously used TIME
comparison instead of DATETIME comparison.
- Adds a new method:
Type_handler_hybrid_field_type::aggregate_for_comparison(Item **, uint nitems),
as a better replacement for agg_cmp_type(), which can handle TIME.
- Splits Item_func_between::val_int() into pieces val_int_cmp_xxx(),
one new method per XXX_RESULT.
- Adds a new virtual method Type_handler::Item_func_between_val_int()
whose implementations use Item_func_between::val_int_cmp_xxx().
- Makes type_handler_longlong and type_handler_newdecimal public,
as they are now needed in item_cmpfunc.cc.
Note:
This patch does not change Item_func_in to use the new aggregation methods,
so it still uses collect_cmp_type()/item_cmp_type() based aggregation.
Item_func_in will be changed in a separate patch and item_cmp_type() will be
removed.
This patch:
- Adds a new virtual method Type_handler::Item_get_cache
- Splits moves Item_cache::get_cache() into the new method, every
"case XXX_RESULT" to the corresponding Type_handler_xxx::Item_get_cache.
- Adds Item::get_cache as a convenience wrapper, to make the caller code
shorter.
- Changes the last argument of Arg_comparator::cache_converted_constant()
from Item_result to "const Type_handler *".
- Removes subselect_engine::cmp_type, subselect_engine::res_type,
subselect_engine::res_field_type and derives subselect_engine
from Type_handler_hybrid_field_type instead.
- Makes Type_handler_varchar public, as it's now needed as the
default data type handler for subselect_engine.
This patch:
- Introduces a new virtuial method Type_handler::set_comparator_func
and moves pieces of the code from the switch in
Arg_comparator::set_compare_func into the corresponding
Type_handler_xxx::set_comparator_func.
- Adds Type_handler::get_handler_by_cmp_type()
- Moves Type_handler_hybrid_field_type::get_handler_by_result_type() to
a static method Type_handler::get_handler_by_result_type(),
for symmetry with similar methods:
* Type_handler::get_handler_by_field_type()
* Type_handler::get_handler_by_real_type()
* Type_handler::get_handler_by_cmp_type()
- Introduces Type_handler_row, to unify the code for the scalar
data types and the ROW data type (currently for comparison purposes only).
- Adds public type_handler_row, as it's now needed in item_row.h
- Makes type_handler_null public, as it's now needed in item_cmpfunc.h
Note, other type_handler_xxx will become public as well later.
- Removes the global variable Arg_comparator::comparator_matrix,
as it's not needed any more.
10.1 introduced a problem:
Execution time for various recursive stages
(walk, update_used_table, and propagate_equal_fields)
in NULLIF is O(recursion_level^2), because complexity is
doubled on every recursion level when we copy args[0] to args[2].
This change fixes to avoid unnecessary recursion in:
- Item_func_nullif::walk
- Item_func_nullif::update_used_tables
- Item_func_nullif::propagate_equal_fields
when possible.
Integer comparison of INT expressions with different signess in BETWEEN
is not safe. Switching to DECIMAL comparison in case if INT arguments
have different signess.
This is a backport of the patch for MDEV-9653 (fixed earlier in 10.1.13).
The code in Item_func_case::fix_length_and_dec() did not
calculate max_length and decimals properly.
In case of any numeric result (DECIMAL, REAL, INT) a generic method
Item_func_case::agg_num_lengths() was called, which could erroneously result
into a DECIMAL item with max_length==0 and decimals==0, so the constructor of
Field_new_decimals tried to create a field of DECIMAL(0,0) type,
which caused a crash.
Unlike Item_func_case, the code responsible for merging attributes in
Item_func_coalesce::fix_length_and_dec() works fine: it has specific execution
branches for all distinct numeric types and correctly creates a DECIMAL(1,0)
column instead of DECIMAL(0,0) for the same set of arguments.
The fix does the following:
- Moves the attribute merging code from Item_func_coalesce::fix_length_and_dec()
to a new method Item_func_hybrid_result_type::fix_attributes()
- Removes the wrong code from Item_func_case::fix_length_and_dec()
and reuses fix_attributes() in both Item_func_coalesce::fix_length_and_dec()
and Item_func_case::fix_length_and_dec()
- Fixes count_real_length() and count_decimal_length() to get an array
of Items as an argument, instead of using Item::args directly.
This is needed for Item_func_case::fix_length_and_dec().
- Moves methods Item_func::count_xxx_length() from "public" to "protected".
- Removes Item_func_case::agg_num_length(), as it's not used any more.
- Additionally removes Item_func_case::agg_str_length(),
as it also was not used (dead code).
Item_func_ifnull::date_op() and Item_func_coalesce::date_op() could
erroneously return 0000-00-00 instead of NULL when get_date()
was called with the TIME_FUZZY_DATES flag, e.g. from LEAST().
- Removing the "diff_if_only_endspace_difference" argument from
MY_COLLATION_HANDLER::strnncollsp(), my_strnncollsp_simple(),
as well as in the function template MY_FUNCTION_NAME(strnncollsp)
in strcoll.ic
- Removing the "diff_if_only_space_different" from ha_compare_text(),
hp_rec_key_cmp().
- Adding a new function my_strnncollsp_padspace_bin() and reusing
it instead of duplicate code pieces in my_strnncollsp_8bit_bin(),
my_strnncollsp_latin1_de(), my_strnncollsp_tis620(),
my_strnncollsp_utf8_cs().
- Adding more tests for better coverage of the trailing space handling.
- Removing the unused definition of HA_END_SPACE_ARE_EQUAL
* only copy args[0] to args[2] after fix_fields (when all item
substitutions have already happened)
* change QT_ITEM_FUNC_NULLIF_TO_CASE (that allows to print NULLIF
as CASE) to QT_ITEM_ORIGINAL_FUNC_NULLIF (that prohibits it).
So that NULLIF-to-CASE is allowed by default and only disabled
explicitly for SHOW VIEW|FUNCTION|PROCEDURE and mysql_make_view.
By default it is allowed (in particular in error messages and
debug output, that can happen anytime before or after optimizer).
don't do special SUM_FUNC_ITEM treatment in NULLIF for views
(as before), but do it for derived tables (when
context_analysis_only == CONTEXT_ANALYSIS_ONLY_DERIVED)
"Re-factor the code for post-join operations".
The patch mainly contains the code ported from mysql-5.6 and
created for two essential architectural changes:
1. WL#5558: Resolve ORDER BY execution method at the optimization stage
2. WL#6071: Inline tmp tables into the nested loops algorithm
The first task was implemented for mysql-5.6 by Ole John Aske.
It allows to make all decisions on ORDER BY operation at the optimization
stage.
The second task implemented for mysql-5.6 by Evgeny Potemkin adds JOIN_TAB
nodes for post-join operations that require temporary tables. It allows
to execute these operations within the nested loops algorithm that used to
be used before this task only for join queries. Besides these task moves
all planning on the execution of these operations from the execution phase
to the optimization phase.
Some other re-factoring changes of mysql-5.6 were pulled in, mainly because
it was easier to pull them in than roll them back. In particular all
changes concerning Ref_ptr_array were incorporated.
The port required some changes in the MariaDB code that concerned the
functionality of EXPLAIN and ANALYZE. This was done mainly by Sergey
Petrunia.
DBUG_ASSERT() added in the patch for MDEV-9181 did not take into account
special circumstances for the prepared statement EXECUTE. Fixig the assert.
Also, extending and fixing comments made during MDEV-9181.
MDEV-9408 CREATE TABLE SELECT MAX(int_column) creates different columns for table vs view
There were three almost identical pieces of the code:
- Field *Item_func::tmp_table_field();
- Field *Item_sum::create_tmp_field();
- Field *create_tmp_field_from_item();
with a difference in very small details (hence the bugs):
Only Item_func::tmp_table_field() was correct, the other two were not.
Removing the two incorrect pieces of the redundant code.
Joining these three functions/methods into a single virtual method
Item::create_tmp_field().
Additionally, moving Item::make_string_field() and
Item::tmp_table_field_from_field_type() from the public into the
protected section of the class declaration, as they are now not
needed outside of Item.
The following left in semi-improved state to keep patch size reasonable:
- Field operator new: left thd_alloc(current_thd)
- Sql_alloc operator new: left thd_alloc(thd_get_current_thd())
- Item_args constructors: left thd_alloc(thd)
- Item_func_interval::fix_length_and_dec(): no THD arg, have to call current_thd
- Item_func_dyncol_exists::val_int(): same
- Item_dyncol_get::val_str(): same
- Item_dyncol_get::val_int(): same
- Item_dyncol_get::val_real(): same
- Item_dyncol_get::val_decimal(): same
- Item_singlerow_subselect::fix_length_and_dec(): same
Problem:
At the end of first execution select_lex->prep_where is pointing to
a runtime created object (temporary table field). As a result
server exits trying to access a invalid pointer during second
execution.
Analysis:
While optimizing the join conditions for the query, after the
permanent transformation, optimizer makes a copy of the new
where conditions in select_lex->prep_where. "prep_where" is what
is used as the "where condition" for the query at the start of execution.
W.r.t the query in question, "where" condition is actually pointing
to a field in the temporary table. As a result, for the second
execution the pointer is no more valid resulting in server exit.
Fix:
At the end of the first execution, select_lex->where will have the
original item of the where condition.
Make prep_where the new place where the original item of select->where
has to be rolled back.
Fixed in 5.7 with the wl#7082 - Move permanent transformations from
JOIN::optimize to JOIN::prepare
Patch for 5.5 includes the following backports from 5.6:
Bugfix for Bug12603141 - This makes the first execute statement in the testcase
pass in 5.5
However it was noted later in in Bug16163596 that the above bugfix needed to
be modified. Although Bug16163596 is reproducible only with changes done for
Bug12582849, we have decided include the fix.
Considering that Bug12582849 is related to Bug12603141, the fix is
also included here. However this results in Bug16317817, Bug16317685,
Bug16739050. So fix for the above three bugs is also part of this patch.
