WITH TIES would not take effect if SELECT DISTINCT was used in a
context where an INDEX is used to resolve the ORDER BY clause.
WITH TIES relies on the `JOIN::order` to contain the non-constant
fields to test the equality of ORDER BY fiels required for WITH TIES.
The cause of the problem was a premature removal of the `JOIN::order`
member during a DISTINCT optimization. This lead to WITH TIES code assuming
ORDER BY only contained "constant" elements.
Disable this optimization when WITH TIES is in effect.
(side-note: the order by removal does not impact any current tests, thus
it will be removed in a future version)
Reviewed by: monty@mariadb.org
There was a bug in JOIN::make_notnull_conds_for_range_scans() when
clearing TABLE->tmp_set, which was used to mark fields that could not be
null.
This function was only used if 'not_null_range_scan=on' is set.
The effect was that tmp_set contained a 'random value' and this caused
the optimizer to think that some fields could not be null.
FLUSH TABLES clears tmp_set and because of this things worked temporarily.
Fixed by clearing tmp_set properly.
Enable use of Rowid Filter optimization with eq_ref access.
Use the following assumptions:
- Assume index-only access cost is 50% of non-index-only access cost.
- Take into account that "Eq_ref access cache" reduces the number of
lookups eq_ref access will make.
= This means the number of Rowid Filter checks is reduced also
= Eq_ref access cost is computed using that assumption (see
prev_record_reads() call), so we should use it in all cost '
computations.
Enable use of Rowid Filter optimization with eq_ref access.
Use the following assumptions:
- Assume index-only access cost is 50% of non-index-only access cost.
- Take into account that "Eq_ref access cache" reduces the number of
lookups eq_ref access will make.
= This means the number of Rowid Filter checks is reduced also
= Eq_ref access cost is computed using that assumption (see
prev_record_reads() call), so we should use it in all cost '
computations.
(Initial patch by Varun Gupta. Amended and added comments).
When the query has both
1. Aggregate functions that require sorting data by group, and
2. Window functions
we need to use two temporary tables. The first temp.table will hold the
join output. Then it is passed to filesort(). Reading it in sorted
order allows to compute the aggregate functions.
Then, we need to write their values into the second temp. table. Then,
Window Function computation step can pass that to filesort() and read
them in the order it needs.
Failure to create the second temp. table would cause an assertion
failure: window function could would not find where to get the values
of the aggregate functions.
The problem was that federated engine does not support comparable rowids
which was not taken into account by semijoin code.
Fixed by checking that we don't use semijoin with tables that does not
support comparable rowids.
Other things:
- Fixed some typos in the code comments
The reason things fails in 10.5 and above is that test_quick_select()
returns -1 (impossible range) for empty tables if there are any
conditions attached.
This didn't happen in 10.4 as the cost for a range was more than for
a table scan with 0 rows and get_key_scan_params() did not create any
range plans and thus did not mark the range as impossible.
The code that checked the 'impossible range' conditions did not take
into account all cases of LEFT JOIN usage.
Adding an extra check if the table is used with an ON condition in case
of 'impossible range' fixes the issue.
The MDEV-25004 test innodb_fts.versioning is omitted because ever since
commit 685d958e38 InnoDB would not allow
writes to a database where the redo log file ib_logfile0 is missing.
it's incorrect to use change_item_tree() to replace arguments
of top-level AND/OR, because they (arguments) are stored in a List,
so a pointer to an argument is in the list_node, and individual
list_node's of top-level AND/OR can be deleted in Item_cond::build_equal_items().
In that case rollback_item_tree_changes() will modify the deleted object.
Luckily, it's not needed to use change_item_tree() for top-level
AND/OR, because the whole top-level item is copied and preserved
in prep_where and prep_on, and restored from there.
So, just don't.
Additionally to the test case in the commit it fixes
* ASAN failure of main.opt_tvc --ps
* ASAN failure of main.having_cond_pushdown --ps
when an internal temporary table field is created from a real field,
a new temp field should only copy a default from the source field
when the latter has it
when creating a temp table field from an actual table field,
these two fields are supposed to be mostly identical
(except for BIT field storage), in particular, temp field should
have the same default as the orig field, even if the sql_mode has
been changed meanwhile (e.g. to include NO_ZERO_DATE)
The problem was that when storing rows into a temporary table,
MIN/MAX items that where marked as constants (as theire value had
been computed at start of query) would be reset.
Fixed by not reseting MIN/MAX items that are marked as const in
Item_sum_min_max::clear().
I have not been able to repeat the problem, but the stack trace indicates
that ha_maria::extra() is called with a null file pointer.
This indicates the table has either never been opened or opened and closed,
with file pointer set to NULL, but ha_maria::extra() is still called.
In JOIN::partial_cleanup() we are only checking of table->is_created(),
which will fail if table was created and later closed.
Fixed by clearing table->created if table is dropped.
I added an assert to is_created() to catch the case that the create
flag does not match 'file'.
