'SELECT DISTINCT a,b FROM t1' should not use temp table if there is unique
index (or primary key) on a.
There are a number of other similar cases that can be calculated without the
use of a temp table : multi-part unique indexes, primary keys or using GROUP BY
instead of DISTINCT.
When a GROUP BY/DISTINCT clause contains all key parts of a unique
index, then it is guaranteed that the fields of the clause will be
unique, therefore we can optimize away GROUP BY/DISTINCT altogether.
This optimization has two effects:
* there is no need to create a temporary table to compute the
GROUP/DISTINCT operation (or the temporary table will be smaller if only GROUP
is removed and DISTINCT stays or if DISTINCT is removed and GROUP BY stays)
* this causes the statement in effect to become updatable in Connector/Java
because the result set columns will be direct reference to the primary key of
the table (instead to the temporary table that it currently references).
Implemented a check that will optimize away GROUP BY/DISTINCT for queries like
the above.
Currently it will work only for single non-constant table in the FROM clause.
mysql-test/r/distinct.result:
Bug #16458: Simple SELECT FOR UPDATE causes "Result Set not updatable" error
- test case
mysql-test/t/distinct.test:
Bug #16458: Simple SELECT FOR UPDATE causes "Result Set not updatable" error
- test case
sql/sql_select.cc:
Bug #16458: Simple SELECT FOR UPDATE causes "Result Set not updatable" error
- disable GROUP BY if contains the fields of a unique index.
This bug in Field_string::cmp resulted in a wrong comparison
with keys in partial indexes over multi-byte character fields.
Given field a is declared as a varchar(16) collate utf8_unicode_ci
INDEX(a(4)) gives us an example of such an index.
Wrong key comparisons could lead to wrong result sets if
the selected query execution plan used a range scan by
a partial index over a utf8 character field.
This also caused wrong results in many other cases.
mysql-test/t/ctype_utf8.test:
Added test cases for bug #14896.
mysql-test/r/ctype_utf8.result:
Added test cases for bug #14896.
sql/field.cc:
Fixed bug #14896.
This bug in Field_string::cmp resulted in a wrong comparison
with keys in partial indexes over multi-byte character fields.
Given field a is declared as a varchar(16) collate utf8_unicode_ci
INDEX(a(4)) gives us an example of such an index.
Wrong key comparisons could lead to wrong result sets if
the selected query execution plan used a range scan by
a partial index over a utf8 character field.
This also caused wrong results in many other cases.
functions in queries
Using MAX()/MIN() on table with disabled indexes (by ALTER TABLE)
results in error 124 (wrong index) from storage engine.
The problem was that optimizer use disabled index to optimize
MAX()/MIN(). Normally it must skip disabled index and perform
table scan.
This patch skips disabled indexes for min/max optimization.
mysql-test/r/myisam.result:
Test case for BUG#20357.
mysql-test/t/myisam.test:
Test case for BUG#20357.
sql/opt_sum.cc:
Skip disabled/ignored indexes for min/max optimization.
The length of the prefix of the pattern string in the LIKE predicate that
determined the index range to be scanned was calculated incorrectly for
multi-byte character sets.
As a result of this in 4. 1 the the scanned range was wider then necessary
if the prefix contained not only one-byte characters.
In 5.0 additionally it caused missing some rows from the result set.
mysql-test/r/ctype_utf8.result:
Added test cases for bug #16674.
mysql-test/t/ctype_utf8.test:
Added test cases for bug #16674.
strings/ctype-mb.c:
Fixed bug #16674.
The length of the prefix of the pattern string in the LIKE predicate that
determined the index range to be scanned was calculated incorrectly for
multi-byte character sets.
As a result of this in 4. 1 the the scanned range was wider then necessary
if the prefix contained not only one-byte characters.
In 5.0 additionally it caused missing some rows from the result set.
The function my_like_range_mb was fixed to calculate the length of
the prefix in a pattern string correctly in all cases.
Added test case for bug#18759 Incorrect string to numeric conversion.
select.test:
Added test case for bug#18759 Incorrect string to numeric conversion.
item_cmpfunc.cc:
Cleanup after fix for bug#18360 removal
sql/item_cmpfunc.cc:
Cleanup after fix for bug#18360 removal
mysql-test/t/select.test:
Added test case for bug#18759 Incorrect string to numeric conversion.
mysql-test/r/select.result:
Added test case for bug#18759 Incorrect string to numeric conversion.
Reverted fix for bug#18360
mysql-test/t/func_in.test:
Reverted fix for bug#18360
mysql-test/r/func_in.result:
Reverted fix for bug#18360
sql/item_cmpfunc.cc:
Reverted fix for bug#18360
tables
Currently in INSERT ... SELECT ... LIMIT ... the compiler uses a
temporary table to store the results of SELECT ... LIMIT .. and then
uses that table as a source for INSERT. The problem is that in some cases
it actually skips the LIMIT clause in doing that and materializes the
whole SELECT result set regardless of the LIMIT.
This fix is limiting the process of filling up the temp table with only
that much rows that will be actually used by propagating the LIMIT value.
mysql-test/r/insert_select.result:
* Bug #9676: INSERT INTO x SELECT .. FROM x LIMIT 1; slows down with big
tables
- a test demonstrating the code path
mysql-test/t/insert_select.test:
* Bug #9676: INSERT INTO x SELECT .. FROM x LIMIT 1; slows down with big
tables
- a test demonstrating the code path
sql/sql_select.cc:
* Bug #9676: INSERT INTO x SELECT .. FROM x LIMIT 1; slows down with big
tables
- pass through the real LIMIT number if the temp table is created for
buffering results.
- set the counter for all the cases when the temp table is not used for
grouping
Certain updates of table joined to self results in unexpected
behavior.
The problem was that record cache was mistakenly enabled for
self-joined table updates. Normally record cache must be disabled
for such updates.
Fixed wrong condition in code that determines whether to use
record cache for self-joined table updates.
Only MyISAM tables were affected.
mysql-test/r/myisam.result:
Test case for BUG#18036.
mysql-test/t/myisam.test:
Test case for BUG#18036.
sql/sql_update.cc:
Fixed wrong condition in code that determines whether to use
record cache for self-joined table updates.
- make sure to disable bulk insert when check for duplicate key is needed
mysql-test/r/ndb_loaddatalocal.result:
New BitKeeper file ``mysql-test/r/ndb_loaddatalocal.result''
mysql-test/t/ndb_loaddatalocal.test:
New BitKeeper file ``mysql-test/t/ndb_loaddatalocal.test''
can lead to a wrong result.
All date/time functions has the STRING result type thus their results are
compared as strings. The string date representation allows a user to skip
some of leading zeros. This can lead to wrong comparison result if a date/time
function result is compared to such a string constant.
The idea behind this bug fix is to compare results of date/time functions
and data/time constants as ints, because that date/time representation is
more exact. To achieve this the agg_cmp_type() is changed to take in the
account that a date/time field or an date/time item should be compared
as ints.
This bug fix is partially back ported from 5.0.
The agg_cmp_type() function now accepts THD as one of parameters.
In addition, it now checks if a date/time field/function is present in the
list. If so, it tries to coerce all constants to INT to make date/time
comparison return correct result. The field for the constant coercion is
taken from the Item_field or constructed from the Item_func. In latter case
the constructed field will be freed after conversion of all constant items.
Otherwise the result is same as before - aggregated with help of the
item_cmp_type() function.
From the Item_func_between::fix_length_and_dec() function removed the part
which was converting date/time constants to int if possible. Now this is
done by the agg_cmp_type() function.
The new function result_as_longlong() is added to the Item class.
It indicates that the item is a date/time item and result of it can be
compared as int. Such items are date/time fields/functions.
Correct val_int() methods are implemented for classes Item_date_typecast,
Item_func_makedate, Item_time_typecast, Item_datetime_typecast. All these
classes are derived from Item_str_func and Item_str_func::val_int() converts
its string value to int without regard to the date/time type of these items.
Arg_comparator::set_compare_func() and Arg_comparator::set_cmp_func()
functions are changed to substitute result type of an item with the INT_RESULT
if the item is a date/time item and another item is a constant. This is done
to get a correct result of comparisons like date_time_function() = string_constant.
mysql-test/r/cast.result:
Fixed wrong test case result after bug fix#16377.
sql/item_timefunc.h:
Fixed bug#16377: result of DATE/TIME functions were compared as strings which
can lead to a wrong result.
The result_as_longlong() function is set to return TRUE for these classes:
Item_date, Item_date_func, Item_func_curtime, Item_func_sec_to_time,
Item_date_typecast, Item_time_typecast, Item_datetime_typecast,
Item_func_makedate.
sql/item_timefunc.cc:
Fixed bug#16377: result of DATE/TIME functions were compared as strings which
can lead to a wrong result.Correct val_int() methods are implemented for classes Item_date_typecast,
Item_func_makedate, Item_time_typecast, Item_datetime_typecast.
sql/item_cmpfunc.h:
Fixed bug#16377: result of DATE/TIME functions were compared as strings which
can lead to a wrong result.
Arg_comparator::set_compare_func() and Arg_comparator::set_cmp_func()
functions are changed to substitute result type of an item with the INT_RESULT
if the item is a date/time item and another item is a constant.
sql/field.cc:
Fixed bug#16377: result of DATE/TIME functions were compared as strings which
can lead to a wrong result.
Field::set_warning(), Field::set_datetime_warning() now use current_thd to get thd if table isn't set.
sql/item_cmpfunc.cc:
Fixed bug#16377: result of DATE/TIME functions were compared as strings which
can lead to a wrong result.
The agg_cmp_type() function now accepts THD as one of parameters.
In addition, it now checks if a date/time field/function is present in the
list. If so, it tries to coerce all constants to INT to make date/time
comparison return correct result. The field for the constant coercion is
taken from the Item_field or constructed from the Item_func. In latter case
the constructed field will be freed after conversion of all constant items.
Otherwise the result is same as before - aggregated with help of the
item_cmp_type() function.
sql/item.h:
The new function result_as_longlong() is added to the Item class.
It indicates that the item is a date/time item and result of it can be
compared as int. Such items are date/time fields/functions.
mysql-test/t/func_time.test:
Added test case fot bug#16377: result of DATE/TIME functions were compared as strings which
can lead to a wrong result.
mysql-test/r/func_time.result:
Added test case fot bug#16377: result of DATE/TIME functions were compared as strings which
can lead to a wrong result.
mysql-test/r/auto_increment.result:
Fix for bug #6880: LAST_INSERT_ID() within a statement
- test result
mysql-test/r/rpl_log.result:
Fix for bug #6880: LAST_INSERT_ID() within a statement
- test result
mysql-test/t/auto_increment.test:
Fix for bug #6880: LAST_INSERT_ID() within a statement
- test case
mysql-test/t/rpl_log.test:
Fix for bug #6880: LAST_INSERT_ID() within a statement
- test case
sql/item_func.cc:
Fix for bug #6880: LAST_INSERT_ID() within a statement
- return the first thd->last_insert_id set (within a query)
into mysql.com:/usr/home/ram/work/4.1.b16546
sql/item_timefunc.cc:
Auto merged
mysql-test/r/func_time.result:
merging
mysql-test/t/func_time.test:
merging
The bug report revealed two problems related to min/max optimization:
1. If the length of a constant key used in a SARGable condition for
for the MIN/MAX fields is greater than the length of the field an
unwanted warning on key truncation is issued;
2. If MIN/MAX optimization is applied to a partial index, like INDEX(b(4))
than can lead to returning a wrong result set.
mysql-test/r/func_group.result:
Added test cases for bug #18206.
mysql-test/t/func_group.test:
Added test cases for bug #18206.
sql/opt_sum.cc:
Fixed bug #18206.
Suppressed the warning about data truncation when store_val_in_field
was used to store keys for the field used in MIN/MAX optimization.
Blocked MIN/MAX optimization for partial keys, such as in INDEX(b(4)).
sql/sql_select.cc:
Fixed bug #18206.
Added a parameter for the function store_val_in_field allowing to
control setting warnings about data truncation in the function.
sql/sql_select.h:
Fixed bug #18206.
Added a parameter for the function store_val_in_field allowing to
control setting warnings about data truncation in the function.
3.23 regression test failure
The member SEL_ARG::min_flag was not initialized,
due to which the condition for no GEOM_FLAG in function
key_or did not choose "Range checked for each record" as
the correct access method.
mysql-test/r/select.result:
testcase for 'Range checked' access method
mysql-test/t/select.test:
testcase for 'Range checked' access method
sql/opt_range.cc:
All of the class members initialized
The IN() function uses agg_cmp_type() to aggregate all types of its arguments
to find out some common type for comparisons. In this particular case the
char() and the int was aggregated to double because char() can contain values
like '1.5'. But all strings which do not start from a digit are converted to
0. thus 'a' and 'z' become equal.
This behaviour is reasonable when all function arguments are constants. But
when there is a field or an expression this can lead to false comparisons. In
this case it makes more sense to coerce constants to the type of the field
argument.
The agg_cmp_type() function now aggregates types of constant and non-constant
items separately. If some non-constant items will be found then their
aggregated type will be returned. Thus after the aggregation constants will be
coerced to the aggregated type.
mysql-test/t/func_in.test:
Added test case for bug#18360: Incorrect type coercion in IN() results in false comparison.
mysql-test/r/func_in.result:
Added test case for bug#18360: Incorrect type coercion in IN() results in false comparison.
sql/item_cmpfunc.cc:
Fixed bug#18360: Incorrect type coercion in IN() results in false comparison.
The agg_cmp_type() function now aggregates types of constant and non-constant
items separately. If some non-constant items will be found then their
aggregated type will be returned. Thus after the aggregation constants will
be coerced to the aggregated type.
In multi-table delete a table for delete can't be used for selecting in
subselects. Appropriate error was raised but wasn't checked which leads to a
crash at the execution phase.
The mysql_execute_command() now checks for errors before executing select
for multi-delete.
mysql-test/t/multi_update.test:
Added test case for bug#19225: unchecked error results in server crash
mysql-test/r/multi_update.result:
Added test case for bug#19225: unchecked error results in server crash
sql/sql_parse.cc:
Fixed bug#19225: unchecked error results in server crash
The mysql_execute_command() now checks for errors before executing select for multi-delete.
argument can lead to a wrong result.
md5() and sha() functions treat their arguments as case sensitive strings.
But when they are compared their arguments were compared as a case
insensitive strings which leads to two functions with different arguments
and thus different results to being identical. This can lead to a wrong
decision made in the range optimizer and thus lead to a wrong result set.
Item_func_md5::fix_length_and_dec() and Item_func_sha::fix_length_and_dec()
functions now set binary collation on their arguments.
sql/item_strfunc.cc:
Fixed bug#15351: Wrong collation used for comparison of md5() and sha()
argument can lead to a wrong result.
Item_func_md5::fix_length_and_dec() and Item_func_sha::fix_length_and_dec()
functions now set binary collation on their arguments.
mysql-test/r/func_str.result:
Added test case for the bug#15351: Wrong collation used for comparison of md5() and sha()
argument can lead to a wrong result.
mysql-test/t/func_str.test:
Added test case for the bug#15351: Wrong collation used for comparison of md5() and sha()
argument can lead to a wrong result.
refining the test case to exclude problems with koi8r on some platforms.
mysql-test/t/mysqlbinlog.test:
replacing unavailble on some platforms koi8r with latin1 still to preserve the essence of the testcase:
to generate utf8 names in binlog, despite client charset was different, and
to digest this binlog.
