- Fix for MySQL BUG#52357 added NESTED_JOIN::is_fully_covered() which would
not take into account that MariaDB's table elimination could eliminate tables
from join plan (and so, from join nest).
Fixed the check in the function to compare post-table-elimination numbers.
The problem could be demonstrated with an outer join of two single-row
tables where the values of the join attributes were null. Any query
with such a join could return a wrong result set if the where
condition of the query was not empty. For queries with empty
where conditions the result sets were correct.
This was the consequence of two bugs in the code:
- Item_equal objects for on conditions of outer joins were
not built if the processed query had no where condition
- the check for null values in the code that evaluated constant
Item_equal objects was incorrect.
Fixed both above problems.
Added a test case for the bug and adjusted results for some other
test cases.
Save no-records constant tables in JOIN::const_table_map before we invoke
eliminate_tables(). Failure to do so caused crash when the same table was
marked as constant two times
mysql-test/r/table_elim.result:
LPBUG#524025 Running RQG outer_join test leads to crash
- Testcase
mysql-test/t/table_elim.test:
LPBUG#524025 Running RQG outer_join test leads to crash
- Testcase
sql/sql_select.cc:
LPBUG#524025 Running RQG outer_join test leads to crash
Save no-records constant tables in JOIN::const_table_map before we invoke eliminate_tables(). Failure to do so caused crash when the same table was marked as constant two times.
- When analying multiple equalities, take into account that they
may not have a single table field that belongs to one of the tables
that we're trying to eliminate (and they are not useful for table
elimination in that case)
mysql-test/r/table_elim.result:
LPBUG#523593: Running RQG optimizer_no_subquery crashes MariaDB
- Testcase
mysql-test/t/table_elim.test:
LPBUG#523593: Running RQG optimizer_no_subquery crashes MariaDB
- Testcase
include/my_global.h:
MWL#17: Table elimination: fixes for windows
- Add ALIGN_MAX_UNIT (assume malloc returns data aligned to this much)
mysql-test/r/table_elim.result:
MWL#17: Table elimination: fixes for windows
- Use only lower-case as EXPLAIN [EXTENDED] changes case of table names
on windows
mysql-test/t/table_elim.test:
MWL#17: Table elimination: fixes for windows
- Use only lower-case as EXPLAIN [EXTENDED] changes case of table names
on windows
sql/opt_table_elimination.cc:
MWL#17: Table elimination: fixes for windows
- Add extra alignment-padding-space for stack-allocated buffers.
- Fix a trivial problem when OR-merging two multi-equalities
- Amend testsuite to provide full gcov coverage
mysql-test/r/table_elim.result:
MWL#17: Table elimination:
- Amend testsuite to provide full gcov coverage
mysql-test/t/table_elim.test:
MWL#17: Table elimination:
- Amend testsuite to provide full gcov coverage
- More testcases
- Set correct dependencies for non-bound multi-equalities.
mysql-test/r/table_elim.result:
MWL#17: Table elimination
- More testcases
mysql-test/t/table_elim.test:
MWL#17: Table elimination
- More testcases
sql/opt_table_elimination.cc:
MWL#17: Table elimination
- Set correct dependencies for non-bound multi-equalities.
- More testcases
- Let add_ft_key() set keyuse->usable
mysql-test/r/table_elim.result:
MWL#17: Table elimination
- More testcases
mysql-test/t/table_elim.test:
MWL#17: Table elimination
- More testcases
sql/sql_select.cc:
MWL#17: Table elimination
- Let add_ft_key() set keyuse->usable
- Make elimination work with aggregate functions. The problem was that aggregate functions
reported all table bits in used_tables(), and that prevented table elimination. Fixed by
making aggregate functions return more correct value from used_tables().
mysql-test/r/ps_11bugs.result:
MWL#17: Table elimination
- Update test results. The difference is because of Item_ref change: outer references to constants
are now recognized as constants, too.
mysql-test/r/subselect.result:
- Update test results. The difference is because of Item_ref change: outer references to constants
are now recognized as constants, too.
mysql-test/r/table_elim.result:
MWL#17: Table elimination
- Check that elimination works in presense of aggreagate functions
mysql-test/t/table_elim.test:
MWL#17: Table elimination
- Check that elimination works in presense of aggreagate functions
sql/item.h:
MWL#17: Table elimination
- Add Item_ref::const_item() which calls (*ref)->const_item(). Before this diff Item_ref used the
default implementation of const_item(){ return used_tables()==0; }. This is no longer true, as
COUNT(*) now has used_tables()==0 but const_item()==FALSE.
sql/item_sum.cc:
MWL#17: Table elimination
- Make Item_sum() and it descendants not to return all bits in used_tables(). This is needed
because otherwise table elimination can't work in presense of aggregate functions
- COUNT(*) now has used_tables()==0 and const_item()==FALSE. Had to change
Item_ref::const_item() to account for this.
sql/item_sum.h:
MWL#17: Table elimination
- Add comments
- First code. Elimination works for simple cases, passes the testsuite.
- Known issues:
= No elimination is done for aggregate functions.
= EXPLAIN EXTENDED shows eliminated tables (I think it better not)
= No benchmark yet
= The code needs some polishing.
mysql-test/r/table_elim.result:
MWL#17: Table elimination
- Testcases
mysql-test/t/table_elim.test:
MWL#17: Table elimination
- Testcases
sql/sql_select.cc:
MWL#17: Table elimination
sql/sql_select.h:
MWL#17: Table elimination
- Added JOIN_TAB::eliminated (is JOIN_TAB the best place to store this flag?)
sql/table.h:
MWL#17: Table elimination
- ADded NESTED_JOIN::n_tables. We need to have the number of real tables remaining in an outer join nest.
