If in the where clause of the a query some comparison conditions on the
field under a MIN/MAX aggregate function contained constants whose sizes
exceeded the size of the field then the query could return a wrong result
when the optimizer had chosen to apply the MIN/MAX optimization.
With such conditions the MIN/MAX optimization still could be applied, yet
it would require a more thorough analysis of the keys built to find
the value of MIN/MAX aggregate functions with index look-ups.
The current patch just prohibits using the MIN/MAX optimization in this
situation.
The MIN/MAX optimizer code from the function opt_sum_query erroneously
did not take into account conjunctive conditions that did not depend on
any table, yet were not identified as constant items. These could be
items containing rand() or PS/SP parameters. These items are supposed
to be evaluated at the execution phase. That's why if such conditions
can be extracted from the WHERE condition the MIN/MAX optimization is
not applied as currently it is always done at the optimization phase.
(In 5.3 expensive subqueries are also evaluated only at the execution
phase. So, if a constant condition with such subquery can be extracted
from the WHERE clause the MIN/MAX optimization should not be applied
in 5.3.)
IF an IN/ALL/SOME predicate with a constant left part is transformed
into an EXISTS subquery the resulting subquery should not be considered
uncacheable if the right part of the predicate is not uncacheable.
Backported the function dbug_print_item() from 5.3. The function is used
only for debugging.
sql/sql_insert.cc:
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
******
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
sql/sql_table.cc:
small cleanup
******
small cleanup
The problem was that optimization code did not take into account later feature when instad of NOT before BETWEEN it has negated flag into the Item_func_between inherited from Item_func_neg_opt. So optimizer tried process NOT BETWEEN as BETWEEN.
The patch just switches off the optimisation for NOT BETWEEN as it was before when NOT function was really used.
compilation error in mysys/my_getsystime.c fixed
some redundant code removed
sec_to_time, time_to_sec, from_unixtime, unix_timestamp, @@timestamp now
use decimal, not double for numbers with a fractional part.
purge_master_logs_before_date() fixed
many bugs in corner cases fixed
mysys/my_getsystime.c:
compilation failure fixed
sql/sql_parse.cc:
don't cut corners. it backfires.
When we create temporary result table for UNION
incorrect max_length for YEAR field is used and
it leads to incorrect field value and incorrect
result string length as YEAR field value calculation
depends on field length.
The fix is to use underlying item max_length for
Item_sum_hybrid::max_length intialization.
mysql-test/r/func_group.result:
test case
mysql-test/t/func_group.test:
test case
sql/field.cc:
added assert
sql/item_sum.cc:
init Item_sum_hybrid::max_length with
use underlying item max_length for
INT result type.
In the string context the MIN() and MAX() functions don't take
into account the unsignedness of the UNSIGNED BIGINT argument
column.
I.e.:
CREATE TABLE t1 (a BIGINT UNSIGNED);
INSERT INTO t1 VALUES (18446668621106209655);
SELECT CONCAT(MAX(a)) FROM t1;
returns -75452603341961.
mysql-test/r/func_group.result:
Test case for bug #11766094.
mysql-test/t/func_group.test:
Test case for bug #11766094.
sql/item.cc:
Bug #11766094 - 59132: MIN() AND MAX() REMOVE UNSIGNEDNESS
The Item_cache_int::val_str() method has been modified to
take into account the unsigned_flag value when converting
data to string.
Item_sum_max/Item_sum_min incorrectly set null_value flag and
attempt to get result in parent functions leads to crash.
This happens due to double evaluation of the function argumet.
First evaluation happens in the comparator and second one
happens in Item_cache::cache_value().
The fix is to introduce new Item_cache object which
holds result of the argument and use this cached value
as an argument of the comparator.
mysql-test/r/func_group.result:
test case
mysql-test/t/func_group.test:
test case
sql/item.cc:
added assertion that ether we have some result or result is NULL.
sql/item_sum.cc:
introduce new Item_cache object which
holds result of the argument and use this cached value
as an argument of the comparator.
sql/item_sum.h:
introduce new Item_cache object which
holds result of the argument and use this cached value
as an argument of the comparator.
when there was one NULL value, AVG(DISTINCT) could forget about other values.
See commit comment of item_sum.cc.
mysql-test/r/func_group.result:
before the code fix, both SELECTs would return NULL
sql/item_sum.cc:
Assume we are executing "SELECT AVG([DISTINCT] some_field) FROM some_table".
and some_field is the single field of some_table for simplicity.
Each time a row is processed (evaluate_join_record()->
end_send_group()->update_sum_func()) an aggregator is notified,
which itself notifies an Item_sum_avg.
Without DISTINCT, this Item_sum_avg immediately increments its
internal "sum of values" and "count of values" (the latter being
Item_sum_avg::count). The count is incremented only if the row's value
is not NULL (in Item_sum_avg::add()), per AVG() semantices. This row's value
is available in args[0] of Item_sum_avg ("args[0]" stands for
"the first argument of the item": it's an Item_field which automatically
receives the row's value when a row is read from the table).
bool Item_sum_avg::add()
{
if (Item_sum_sum::add()) << calculates the sum (ignores NULL)
return TRUE;
if (!args[0]->null_value)<<if added value is not NULL
count++; <<increment "count"
return FALSE;
}
and everything works.
With DISTINCT, when a row is processed by evaluate_join_record(),
Item_sum_avg does no immediate computation, rather stores
the row's value in a tree (to throw the value away if it is a duplicate
of previous value, otherwise to remember all
distinct values). It's only when it's time to send the average to the
user (at end of the query:
sub_select(end_of_records=true)->end_send_group()->
select_send->send_data()->Protocol::send_result_set_row()->
Item::send()->Item_sum_avg->val_str()), that we iterate over the tree,
compute the sum and count: for this, for each element of the tree,
Item_sum_avg::add() is called and has the same two steps as before:
* Item_sum_sum::add() updates the sum (finding the tree element's value
correctly, and determining correctly its NULLness - look for "arg_is_null"
in that function)
* the "if (!args[0]->null_value)" test right after, breaks: it uses args[0],
which isn't the tree's element but rather the value for the last row
processed by evaluate_join_record(). So if that last row was NULL,
"count" stays 0 for each row, and AVG() then returns NULL (count==0 =>
NULL, per AVG() semantics).
The fix is to let the aggregator tell whether the value
it just saw was NULL. The aggregator knows where to get the info
thanks to virtual functions. Item_sum_sum::add() now asks
the aggregator. Item_sum_avg() also asks the aggregator
and then knows it shouldn't increment "count".
sql/item_sum.h:
Aggregator can now tell about value/NULLness of just-aggregated value
== MYSQL_TYPE_LONGLONG
A MIN/MAX() function with a subquery as its argument could lead
to a debug assertion on debug builds or wrong data on release
ones.
The problem was a combination of the following factors:
- Item_sum_hybrid::fix_fields() might use the argument
(args[0]) to calculate 'hybrid_field_type' which was later used
to decide how the data should be sent to the client.
- Item_sum::make_field() might use the argument again to
calculate the field's type when sending result set metadata to
the client.
- The argument could be changed in between these two calls via
Item::set_arg() leading to inconsistent metadata being
reported.
Here is what was happening for the bug's test case:
1. Item_sum_hybrid::fix_fields() calculates hybrid_field_type
as MYSQL_TYPE_LONGLONG based on args[0] which is an
Item::SUBSELECT_ITEM at that time.
2. A temporary table is created to execute the
query. create_tmp_field_from_item() creates a Field_long object
according to the subselect's max_length.
3. The subselect item in Item_sum_hybrid is replaced by the
Item_field object referencing the newly created Field_long.
4. Item_sum::make_field() rightfully returns the
MYSQL_TYPE_LONG type when calculating the result set metadata.
5. When sending the actual data, Item::send() relies on the
virtual field_type() function which in our case returns
previously calculated hybrid_field_type == MYSQL_TYPE_LONGLONG.
It looks like the only solution is to never refer to the
argument's metadata after the result metadata has been
calculated in fix_fields(), since the argument itself may be
different by then. In this sense, Item_sum::make_field() should
never be used, because it may rely on the argument's metadata
and is only called after fix_fields(). The "default"
implementation in Item::make_field() should be used instead as
it relies only on field_type(), but not on the argument's type.
Fixed by removing Item_sum::make_field() so that the superclass
implementation Item::make_field() is always used.
mysql-test/r/func_group.result:
Added a test case for bug #54465.
mysql-test/t/func_group.test:
Added a test case for bug #54465.
sql/item_sum.cc:
Removed Item_sum::make_field() so that the superclass
implementation Item::make_field() is always used.
sql/item_sum.h:
Removed Item_sum::make_field() so that the superclass
implementation Item::make_field() is always used.
The Item_cache_datetime::val_str function wasn't taking into account that time
could be negative. This led to failed assertion.
Now Item_cache_datetime::val_str correctly converts negative time values
from integer to string representation.
mysql-test/r/func_group.result:
Added a test case for the bug#56120.
mysql-test/t/func_group.test:
Added a test case for the bug#56120.
sql/item.cc:
Bug#56120: Failed assertion on MIX/MAX on negative time value
Now Item_cache_datetime::val_str correctly converts negative time values
from integer to string representation.
A typo in the Item_cache_datetime::val_str caused an assertion to fail on the
maximum time value.
mysql-test/r/func_group.result:
A test case for the bug#55648.
mysql-test/t/func_group.test:
A test case for the bug#55648.
sql/item.cc:
Bug#55648: Server crash on MIX/MAX on maximum time value
Corrected assertion.
MySQL manual describes values of the YEAR(2) field type as follows:
values 00 - 69 mean 2000 - 2069 years and values 70 - 99 mean 1970 - 1999
years. MIN/MAX and comparison functions was comparing them as int values
thus producing wrong result.
Now the Arg_comparator class is extended with compare_year function which
performs correct comparison of the YEAR type.
The Item_sum_hybrid class now uses Item_cache and Arg_comparator objects to
correctly calculate its value.
To allow Arg_comparator to use func_name() function for Item_func and Item_sum
objects the func_name declaration is moved to the Item_result_field class.
A helper function is_owner_equal_func is added to the Arg_comparator class.
It checks whether the Arg_comparator object owner is the <=> function or not.
A helper function setup is added to the Item_sum_hybrid class. It sets up
cache item and comparator.
mysql-test/r/func_group.result:
Added a test case for the bug#43668.
mysql-test/t/func_group.test:
Added a test case for the bug#43668.
sql/item.cc:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
Now Item_cache_int returns the type of cached item.
sql/item.h:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
To allow Arg_comparator to use func_name() function for Item_func and Item_sum
objects the func_name declaration is moved to the Item_result_field class.
sql/item_cmpfunc.cc:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
The Arg_comparator class is extended with compare_year function which
performs correct comparison of the YEAR type.
sql/item_cmpfunc.h:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
The year_as_datetime variable is added to the Arg_comparator class.
It's set to TRUE when YEAR value should be converted to the
YYYY-00-00 00:00:00 format for correct YEAR-DATETIME comparison.
sql/item_geofunc.cc:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
Item_func_spatial_rel::val_int chenged to use Arg_comparator's string
buffers.
sql/item_subselect.h:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
Added an implementation of the virtual func_name function.
sql/item_sum.cc:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
The Item_sum_hybrid class now uses Item_cache and Arg_comparator objects to
correctly calculate its value.
A helper function setup is added to the Item_sum_hybrid class. It sets up
cache item and comparator.
sql/item_sum.h:
Bug#43668: Wrong comparison and MIN/MAX for YEAR(2)
The Item_sum_hybrid class now uses Item_cache and Arg_comparator objects to
correctly calculate its value.
Added an implementation of the virtual func_name function.
columns without where/group
Simple SELECT with implicit grouping used to return many rows if
the query was ordered by the aggregated column in the SELECT
list. This was incorrect because queries with implicit grouping
should only return a single record.
The problem was that when JOIN:exec() decided if execution needed
to handle grouping, it was assumed that sum_func_count==0 meant
that there were no aggregate functions in the query. This
assumption was not correct in JOIN::exec() because the aggregate
functions might have been optimized away during JOIN::optimize().
The reason why queries without ordering behaved correctly was
that sum_func_count is only recalculated if the optimizer chooses
to use temporary tables (which it does in the ordered case).
Hence, non-ordered queries were correctly treated as grouped.
The fix for this bug was to remove the assumption that
sum_func_count==0 means that there is no need for grouping. This
was done by introducing variable "bool implicit_grouping" in the
JOIN object.
mysql-test/r/func_group.result:
Add test for BUG#47280
mysql-test/t/func_group.test:
Add test for BUG#47280
sql/opt_sum.cc:
Improve comment for opt_sum_query()
sql/sql_class.h:
Add comment for variables in TMP_TABLE_PARAM
sql/sql_select.cc:
Introduce and use variable implicit_grouping instead of (!group_list && sum_func_count) in places that need to test if grouping is required. Also added comments for: optimization of aggregate fields for implicitly grouped queries (JOIN::optimize) and choice of end_select method (JOIN::execute)
sql/sql_select.h:
Add variable implicit_grouping, which will be TRUE for queries that contain aggregate functions but no GROUP BY clause. Also added comment to sort_and_group variable.
ONLY_FULL_GROUP_BY
The check for non-aggregated columns in queries with aggregate function, but without
GROUP BY was treating all the parts of the query as if they are in the SELECT list.
Fixed by ignoring the non-aggregated fields in the WHERE clause.
mysql-test/r/func_group.result:
Bug #39656: test case
mysql-test/t/func_group.test:
Bug #39656: test case
sql/sql_select.cc:
Bug #39656: ignore the new non-aggregated column refs in a WHERE
by saving the state so far and then adding only the new values of the other
parts of the bitmask.
The optimizer pulls up aggregate functions which should be aggregated in
an outer select. At some point it may substitute such a function for a field
in the temporary table. The setup_copy_fields function doesn't take this
into account and may overrun the copy_field buffer.
Fixed by filtering out the fields referenced through the specialized
reference for aggregates (Item_aggregate_ref).
Added an assertion to make sure bugs that cause similar discrepancy
don't go undetected.
mysql-test/r/func_group.result:
Bug #37348: test case
mysql-test/t/func_group.test:
Bug #37348: test case
sql/item.cc:
Bug #37348: Added a way to distinguish Item_aggregate_ref from the other types of refs
sql/item.h:
Bug #37348: Added a way to distinguish Item_aggregate_ref from the other types of refs
sql/sql_select.cc:
Bug #37348:
- Don't consider copying field references
seen through Item_aggregate_ref
- check for discrepancies between the number of expected
fields that need copying and the actual fields copied.
