The wrong result set returned by the left join query from
the bug test case happened due to several inconsistencies
and bugs of the legacy mysql code.
The bug test case uses an execution plan that employs a scan
of a materialized IN subquery from the WHERE condition.
When materializing such an IN- subquery the optimizer injects
additional equalities into the WHERE clause. These equalities
express the constraints imposed by the subquery predicate.
The injected equality of the query in the test case happens
to belong to the same equality class, and a new equality
imposing a condition on the rows of the materialized subquery
is inferred from this class. Simultaneously the multiple
equality is added to the ON expression of the LEFT JOIN
used in the main query.
The inferred equality of the form f1=f2 is taken into account
when optimizing the scan of the rows the temporary table
that is the result of the subquery materialization: only the
values of the field f1 are read from the table into the record
buffer. Meanwhile the inferred equality is removed from the
WHERE conditions altogether as a constraint on the fields
of the temporary table that has been used when filling this table.
This equality is supposed to be removed from the ON expression
when the multiple equalities of the ON expression are converted
into an optimal set of equality predicates. It supposed to be
removed from the ON expression as an equality inferred from only
equalities of the WHERE condition. Yet, it did not happened
due to the following bug in the code.
Erroneously the code tried to build multiple equality for ON
expression twice: the first time, when it called optimize_cond()
for the WHERE condition, the second time, when it called
this function for the HAVING condition. When executing
optimize_con() for the WHERE condition a reference
to the multiple equality of the WHERE condition is set
in the multiple equality of the ON expression. This reference
would allow later to convert multiple equalities of the
ON expression into equality predicates. However the
the second call of build_equal_items() for the ON expression
that happened when optimize_cond() was called for the
HAVING condition reset this reference to NULL.
This bug fix blocks calling build_equal_items() for ON
expressions for the second time. In general, it will be
beneficial for many queries as it removes from ON
expressions any equalities that are to be checked for the
WHERE condition.
The patch also fixes two bugs in the list manipulation
operations and a bug in the function
substitute_for_best_equal_field() that resulted
in passing wrong reference to the multiple equalities
of where conditions when processing multiple
equalities of ON expressions.
The code of substitute_for_best_equal_field() and
the code the helper function eliminate_item_equal()
were also streamlined and cleaned up.
Now the conversion of the multiple equalities into
an optimal set of equality predicates first produces
the sequence of the all equalities processing multiple
equalities one by one, and, only after this, it inserts
the equalities at the beginning of the other conditions.
The multiple changes in the output of EXPLAIN
EXTENDED are mainly the result of this streamlining,
but in some cases is the result of the removal of
unneeded equalities from ON expressions. In
some test cases this removal were reflected in the
output of EXPLAIN resulted in disappearance of
“Using where” in some rows of the execution plans.
two tests still fail:
main.innodb_icp and main.range_vs_index_merge_innodb
call records_in_range() with both range ends being open
(which triggers an assert)
Print the warning(note):
YEAR(x) is deprecated and will be removed in a future release. Please use YEAR(4) instead
on "CREATE TABLE ... YEAR(x)" or "ALTER TABLE MODIFY ... YEAR(x)", where x != 4
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 result of materialization of the right part of an IN subquery predicate
is placed into a temporary table. Each row of the materialized table is
distinct. A unique key over all fields of the temporary table is defined and
created. It allows to perform key look-ups into the table.
The table created for a materialized subquery can be accessed by key as
any other table. The function best_access-path search for the best access
to join a table to a given partial join. With some where conditions this
function considers a possibility of a ref_or_null access. If such access
employs the unique key on the temporary table then when estimating
the cost this access the function tries to use the array rec_per_key. Yet,
such array is not built for this unique key. This causes a crash of the server.
Rows returned by the subquery that contain nulls don't have to be placed
into temporary table, as they cannot be match any row produced by the
left part of the subquery predicate. So all fields of the temporary table
can be defined as non-nullable. In this case any ref_or_null access
to the temporary table does not make any sense and it does not make sense
to estimate such an access.
The fix makes sure that the temporary table for a materialized IN subquery
is defined with columns that are all non-nullable. The also ensures that
any row with nulls returned by the subquery is not placed into the
temporary table.
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.
in EXPLAIN as select_type==MATERIALIZED.
Before, we had select_type==SUBQUERY and it was difficult to tell materialized
subqueries from uncorrelated scalar-context subqueries.
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.
Resolved all conflicts, bad merges and fixed a few minor bugs in the code.
Commented out the queries from multi_update, view, subselect_sj, func_str,
derived_view, view_grant that failed either with crashes in ps-protocol or
with wrong results.
The failures are clear indications of some bugs in the code and these bugs
are to be fixed.
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.
== 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.
WL#2474 "Multi Range Read: Change the default MRR implementation to implement new MRR interface"
WL#2475 "Batched range read functions for MyISAM/InnoDb"
"Index condition pushdown for MyISAM/InnoDB"
Igor's fix from sp1r-igor@olga.mysql.com-20080330055902-07614:
There could be observed the following problems:
1. EXPLAIN did not mention pushdown conditions from on expressions in the
'extra' column. As a result if a query had no where conditions pushed
down to a table, but had on conditions pushed to this table the 'extra'
column in the EXPLAIN for the table missed 'using where'.
2. Conditions for ref access were not eliminated from on expressions
though such conditions were eliminated from the where condition.
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.
Various parts of code used different 'precision' arguments for sprintf("%g") when converting
floating point numbers to a string. This led to differences in results in some cases
depending on whether the text-based or prepared statements protocol is used for a query.
Fixed by changing arguments to sprintf("%g") to always be 15 (DBL_DIG) so that results are
consistent regardless of the protocol.
This patch will be null-merged to 6.0 as the problem does not exists there (fixed by the
patch for WL#2934).
client/sql_string.cc:
Use 15 (DBL_DIG) as a precision argument for sprintf(), as Field_double::val_str() does.
libmysql/libmysql.c:
Use 15 (DBL_DIG) as a precision argument for sprintf(), as Field_double::val_str() does.
mysql-test/r/archive_gis.result:
Fixed test results to take additional precision into account.
mysql-test/r/func_group.result:
Fixed test results to take additional precision into account.
mysql-test/r/func_math.result:
Fixed test results to take additional precision into account.
mysql-test/r/func_str.result:
Fixed test results to take additional precision into account.
mysql-test/r/gis.result:
Fixed test results to take additional precision into account.
mysql-test/r/innodb_gis.result:
Fixed test results to take additional precision into account.
mysql-test/r/select.result:
Fixed test results to take additional precision into account.
mysql-test/r/sp.result:
Fixed test results to take additional precision into account.
mysql-test/r/type_float.result:
Fixed test results to take additional precision into account.
mysql-test/t/type_float.test:
Fixed test results to take additional precision into account.
sql/sql_string.cc:
Use 15 (DBL_DIG) as a precision argument for sprintf(), as Field_double::val_str() does.
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.
into kaamos.(none):/data/src/opt/bug34512/my51
mysql-test/r/func_group.result:
Auto merged
mysql-test/t/func_group.test:
Auto merged
sql/item_sum.cc:
Auto merged
returns wrong results
Casting AVG() to DECIMAL led to incorrect results when the arguments
had a non-DECIMAL type, because in this case
Item_sum_avg::val_decimal() performed the division by the number of
arguments twice.
Fixed by changing Item_sum_avg::val_decimal() to not rely on
Item_sum_sum::val_decimal(), i.e. calculate sum and divide using
DECIMAL arithmetics for DECIMAL arguments, and utilize val_real() with
subsequent conversion to DECIMAL otherwise.
mysql-test/r/func_group.result:
Added a test case for bug #34512.
mysql-test/t/func_group.test:
Added a test case for bug #34512.
sql/item_sum.cc:
Do not use Item_sum_sum::val_decimal() in Item_sum_avg::val_decimal()
because the first one, depending on the arguments type, may return
either the sum of the arguments, or the average calculated by the
virtual val_real() method of Item_sum_avg. Instead, do our own
calculation based on the arguments type.
