- Call tmp_having->update_used_tables() *before* we have call JOIN::cleanup().
Making the call after join::cleanup() is not allowed, because subquery
predicate items walk parent join's JOIN_TAB structures. Which can be
invalidated by JOIN::cleanup().
When iterating over a list of conditions using List_iterator
the function remove_eq_conds should skip all predicates that
replace a condition from the list. Otherwise it can come to
an infinite recursion.
<non-nullable datatime field> IS NULL in outer joins with
that in inner joins.
Previously such condition was transformed into the condition
<non-nullable datatime field> = 0 unless the field belonged
to an inner table of an outer join. In this case the predicate
was interpreted as for any other field.
Now if the field in the predicate <non-nullable datatime field> IS NULL
belongs to an inner table of an outer join the predicate is
transformed into the disjunction
<non-nullable datatime field> = 0 OR <non-nullable datatime field> IS NULL.
This is fully compatible with the semantics of such predicates in 5.5.
- When restore_prev_nj_state() is called for the table that is
the last remaining child of a nested join, do not leave that
nested join's bit in join->cur_embedding_map.
This bug was the result of incompleteness of the patch for bug mdev-4177.
When an OR condition is simplified to a single conjunct it is merged
into the embedding AND condition. Multiple equalities are also merged,
and any field item involved in those equality should acquire a pointer
to a the multiple equality formed by this merge.
The function make_join_statistics checks whether eq_ref access uses only
constant expressions, and, if this is the case the function performs
constant row substitution. The code of this check must take into account
hidden components of extended secondary keys.
fulltext search was initialized for all MATCH ... AGAINST items
at the end of the JOIN::optimize(). But since 5.3 derived tables
are initialized lazily on first use, very late in the sub_select().
Skip Item_func_match::init_search initialization if the corresponding
table isn't open yet; repeat fulltext initialization for all
not-yet-initialized MATCH ... AGAINST items after creating derived tables.
init join->top_join_tab_count to be in sync with join->join_tab=stat,
otherwise a query can be killed in-between and join_tab's won't be deleted
(JOIN::cleanup won't call JOIN_TAB::cleanup)
One of them is quite serious: the function table_cond_selectivity used
the TABLE_REF structure for ref/eq_ref access methods as if they had been
filled. In fact these structure are filled after the best execution plan
has been chosen.
The other bugs happened due to:
- an erroneous attempt at get statistics on the result of materialization
of a view
- incorrect handling of ranges with no left/right limits when calculating
selectivity of range conditions on non-indexed columns
- lack of cleanup for some newly introduced fields
In some cases, when using views the optimizer incorrectly determined
possible join orders for queries with nested outer and inner joins.
This could lead to invalid execution plans for such queries.
RETURNS RANDOM DATA
MySQL 5.5 specific version of bugfix.
When Loose Index Scan Range access is used, MySQL execution needs
to copy non-aggregated fields. end_send() checked if this was
necessary by checking if join_tab->select->quick had type
QS_TYPE_GROUP_MIN_MAX.
In this bug, however, MySQL created a sort index to sort the rows
read from this range access method. create_sort_index() deletes
join_tab->select->quick which makes it impossible to inquire
the join_tab if LIS has been used.
The fix for MySQL 5.5 is to introduce a variable in JOIN_TAB
that stores whether or not LIS has been used. There is no need
for this variable in later MySQL versions because the relevant
code has been refactored.
RETURNS RANDOM DATA
MySQL 5.5 specific version of bugfix.
When Loose Index Scan Range access is used, MySQL execution needs
to copy non-aggregated fields. end_send() checked if this was
necessary by checking if join_tab->select->quick had type
QS_TYPE_GROUP_MIN_MAX.
In this bug, however, MySQL created a sort index to sort the rows
read from this range access method. create_sort_index() deletes
join_tab->select->quick which makes it impossible to inquire
the join_tab if LIS has been used.
The fix for MySQL 5.5 is to introduce a variable in JOIN_TAB
that stores whether or not LIS has been used. There is no need
for this variable in later MySQL versions because the relevant
code has been refactored.
