A few problems were found in the fix for bug 43668:
1) Comparison of the YEAR column with NULL always returned TRUE;
2) Comparison of the YEAR column with constants always returned
unpredictable result;
3) Unnecessary conversion warnings when comparing a non-integer
constant with a NULL value in the YEAR column;
The problems described above have been resolved with an
exception: zero (i.e. invalid) YEAR column value comparison
with 00 or 2000 still fail (it is not a regression and it was
not a regression), so MIN/MAX on YEAR column containing zero
value still fail.
mysql-test/r/type_year.result:
Test case for bug #49480.
mysql-test/t/type_year.test:
Test case for bug #49480.
sql/item_cmpfunc.cc:
- The get_year_value() function has been modified to make its
return value compatible with the get_datetime_value() return
value (i.e. to convert numeric values into the YYYY0000000000
(YYYY-00-00 00:00:00) form.
- The Arg_comparator::set_cmp_func method has been modified to
use the get_year_value function if get_datetime_value() is not
applicable.
From now only 2 cases have a special processing there:
* both comparing items have MYSQL_TYPE_YEAR field type
or
* one item have is MYSQL_TYPE_YEAR and other one is
is_datetime()-compliant.
- New helper function try_year_cmp_func() has been
added for the better code readability to call from
Arg_comparator::set_cmp_func().
- The Arg_comparator::compare_year method has been removed
since get_year_value() is compatible with the old
Arg_comparator::compare_datetime method that doesn't have
problems #1-#3 (see whole patch entry commentary).
sql/item_cmpfunc.h:
- New helper function try_year_cmp_func() has been
added for the better code readability to call from
Arg_comparator::set_cmp_func().
- Unnecessary Arg_comparator::year_as_datetime and
Arg_comparator::compare_year() declarations have been
removed.
A few problems were found in the fix for bug 43668:
1) Comparison of the YEAR column with NULL always returned TRUE;
2) Comparison of the YEAR column with constants always returned
unpredictable result;
3) Unnecessary conversion warnings when comparing a non-integer
constant with a NULL value in the YEAR column;
The problems described above have been resolved with an
exception: zero (i.e. invalid) YEAR column value comparison
with 00 or 2000 still fail (it is not a regression and it was
not a regression), so MIN/MAX on YEAR column containing zero
value still fail.
Arg_comparator uses Item_cache objects to store constants being compared when
they're need a type conversion. Because this cache wasn't initialized properly
Arg_comparator might produce wrong comparison result.
The Arg_comparator::cache_converted_constant function now initializes cache
prior to usage.
mysql-test/r/select.result:
Added a test case for he bug#49489.
mysql-test/t/select.test:
Added a test case for he bug#49489.
sql/item_cmpfunc.cc:
Bug#49489: Uninitialized cache led to a wrong result.
The Arg_comparator::cache_converted_constant function now initializes cache
prior to usage.
Arg_comparator uses Item_cache objects to store constants being compared when
they're need a type conversion. Because this cache wasn't initialized properly
Arg_comparator might produce wrong comparison result.
The Arg_comparator::cache_converted_constant function now initializes cache
prior to usage.
field='const1' AND field='const2' in some cases
Building multiple equality predicates containing
a constant which is compared as a datetime (with a field)
we should take this fact into account and compare the
constant with another possible constatns as datetimes
as well.
E.g. for the
SELECT ... WHERE a='2001-01-01' AND a='2001-01-01 00:00:00'
we should compare '2001-01-01' with '2001-01-01 00:00:00' as
datetimes but not as strings.
mysql-test/r/select.result:
Fix for bug#49199: Optimizer handles incorrectly:
field='const1' AND field='const2' in some cases
- test result.
mysql-test/t/select.test:
Fix for bug#49199: Optimizer handles incorrectly:
field='const1' AND field='const2' in some cases
- test case.
sql/item_cmpfunc.cc:
Fix for bug#49199: Optimizer handles incorrectly:
field='const1' AND field='const2' in some cases
- adding a constant to Item_equal compare it as
a datetime value with stored one if there's a
date[time] field in a equality predicate.
sql/item_cmpfunc.h:
Fix for bug#49199: Optimizer handles incorrectly:
field='const1' AND field='const2' in some cases
- adding a constant to Item_equal compare it as
a datetime value with stored one if there's a
date[time] field in a equality predicate.
sql/sql_select.cc:
Fix for bug#49199: Optimizer handles incorrectly:
field='const1' AND field='const2' in some cases
- adding a constant to Item_equal compare it as
a datetime value with stored one if there's a
date[time] field in a equality predicate.
field='const1' AND field='const2' in some cases
Building multiple equality predicates containing
a constant which is compared as a datetime (with a field)
we should take this fact into account and compare the
constant with another possible constatns as datetimes
as well.
E.g. for the
SELECT ... WHERE a='2001-01-01' AND a='2001-01-01 00:00:00'
we should compare '2001-01-01' with '2001-01-01 00:00:00' as
datetimes but not as strings.
Actually there is two different bugs.
The first one caused crash on queries with WHERE condition over views
containing WHERE condition. A wrong check for prepared statement phase led
to items for view fields being allocated in the execution memory and freed
at the end of execution. Thus the optimized WHERE condition refers to
unallocated memory on the second execution and server crashed.
The second one caused by the Item_cond::compile function not saving changes
it made to the item tree. Thus on the next execution changes weren't
reverted and server crashed on dereferencing of unallocated space.
The new helper function called is_stmt_prepare_or_first_stmt_execute
is added to the Query_arena class.
The find_field_in_view function now uses
is_stmt_prepare_or_first_stmt_execute() to check whether
newly created view items should be freed at the end of the query execution.
The Item_cond::compile function now saves changes it makes to item tree.
mysql-test/r/ps.result:
Added a test case for the bug#48508.
mysql-test/t/ps.test:
Added a test case for the bug#48508.
sql/item_cmpfunc.cc:
Bug#48508: Crash on prepared statement re-execution.
The Item_cond::compile function now saves changes it makes to item tree.
sql/sql_base.cc:
Bug#48508: Crash on prepared statement re-execution.
The find_field_in_view function now uses
is_stmt_prepare_or_first_stmt_execute() to check whether
newly created view items should be freed at the end of the query execution.
sql/sql_class.h:
Bug#48508: Crash on prepared statement re-execution.
The Query_arena::is_stmt_prepare_or_first_sp_execute function now correctly
do its check.
Actually there is two different bugs.
The first one caused crash on queries with WHERE condition over views
containing WHERE condition. A wrong check for prepared statement phase led
to items for view fields being allocated in the execution memory and freed
at the end of execution. Thus the optimized WHERE condition refers to
unallocated memory on the second execution and server crashed.
The second one caused by the Item_cond::compile function not saving changes
it made to the item tree. Thus on the next execution changes weren't
reverted and server crashed on dereferencing of unallocated space.
The new helper function called is_stmt_prepare_or_first_stmt_execute
is added to the Query_arena class.
The find_field_in_view function now uses
is_stmt_prepare_or_first_stmt_execute() to check whether
newly created view items should be freed at the end of the query execution.
The Item_cond::compile function now saves changes it makes to item tree.
----------------------------------------------------------------------
ChangeSet@1.2571, 2008-04-08 12:30:06+02:00, vvaintroub@wva. +122 -0
Bug#32082 : definition of VOID in my_global.h conflicts with Windows
SDK headers
VOID macro is now removed. Its usage is replaced with void cast.
In some cases, where cast does not make much sense (pthread_*, printf,
hash_delete, my_seek), cast is ommited.
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.
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.
- Moved some code from innodb_plugin to xtradb, to ensure that all tests runs
- Did changes in pbxt and maria storage engines becasue of changes in thd->query
- Reverted wrong code in sql_table.cc for how ROW_FORMAT is used.
This is a re-commit of Monty's merge to eliminate an extra commit from
MySQL-5.1.42 that was accidentally included in the merge.
This is a merge of the MySQL 5.1.41 clone-off (clone-5.1.41-build). In
case there are any extra changes done before final MySQL 5.1.41
release, these will need to be merged later before MariaDB 5.1.41
release.
When values of different types are compared they're converted to a type that
allows correct comparison. This conversion is done for each comparison and
takes some time. When a constant is being compared it's possible to cache the
value after conversion to speedup comparison. In some cases (large dataset,
complex WHERE condition with many type conversions) query might be executed
7% faster.
A test case isn't provided because all changes are internal and isn't visible
outside.
The behavior of the Item_cache is changed to cache values on the first request
of cached value rather than at the moment of storing item to be cached.
A flag named value_cached is added to the Item_cache class. It's set to TRUE
when cache holds the value of the last stored item.
Function named cache_value() is added to the Item_cache class and derived classes.
This function actually caches the value of the saved item.
Item_cache_xxx::store functions now only store item to be cached and set
value_cached flag to FALSE.
Item_cache_xxx::val_xxx functions are changed to call cache_value function
prior to returning cached value if value_cached is FALSE.
The Arg_comparator::set_cmp_func function now calls cache_converted_constant
to cache constants if they need a type conversion.
The Item_cache::get_cache function is overloaded to allow setting of the
cache type.
The cache_converted_constant function is added to the Arg_comparator class.
It checks whether a value can and should be cached and if so caches it.
sql/item.cc:
Bug#34384: Slow down on constant conversion.
Function named cache_value() is added to the Item_cache class and derived classes.
This function actually caches the value of the saved item.
Item_cache_xxx::store functions now only store item to be cached and set
value_cached flag to FALSE.
Item_cache_xxx::val_xxx functions are changed to call cache_value function
prior to returning cached value if value_cached is FALSE.
The Item_cache::get_cache function is overloaded to allow setting of the
cache type.
sql/item.h:
Bug#34384: Slow down on constant conversion.
A flag named value_cached is added to the Item_cache class. It's set to TRUE
when we need to start caching values when the store method is called.
Function named cache_value() is added to the Item_cache class and derived classes.
sql/item_cmpfunc.cc:
Bug#34384: Slow down on constant conversion.
A helper function cache_converted_constant is added to the Arg_comparator class.
It checks whether a given item can and should be cached and caches it if so.
The Arg_comparator::set_cmp_func function now calls cache_converted_constant
to cache constants if they need a type conversion.
sql/item_cmpfunc.h:
Bug#34384: Slow down on constant conversion.
The cache_converted_constant function is added to the Arg_comparator class.
It checks whether a value can and should be cached and if so caches it.
sql/item_subselect.cc:
Bug#34384: Slow down on constant conversion.
Force immediate caching of subselect result.
sql/item_xmlfunc.cc:
Bug#34384: Slow down on constant conversion.
sql/sp_rcontext.cc:
Bug#34384: Slow down on constant conversion.
Force immediate caching of values of an SP CASE function.
When values of different types are compared they're converted to a type that
allows correct comparison. This conversion is done for each comparison and
takes some time. When a constant is being compared it's possible to cache the
value after conversion to speedup comparison. In some cases (large dataset,
complex WHERE condition with many type conversions) query might be executed
7% faster.
A test case isn't provided because all changes are internal and isn't visible
outside.
The behavior of the Item_cache is changed to cache values on the first request
of cached value rather than at the moment of storing item to be cached.
A flag named value_cached is added to the Item_cache class. It's set to TRUE
when cache holds the value of the last stored item.
Function named cache_value() is added to the Item_cache class and derived classes.
This function actually caches the value of the saved item.
Item_cache_xxx::store functions now only store item to be cached and set
value_cached flag to FALSE.
Item_cache_xxx::val_xxx functions are changed to call cache_value function
prior to returning cached value if value_cached is FALSE.
The Arg_comparator::set_cmp_func function now calls cache_converted_constant
to cache constants if they need a type conversion.
The Item_cache::get_cache function is overloaded to allow setting of the
cache type.
The cache_converted_constant function is added to the Arg_comparator class.
It checks whether a value can and should be cached and if so caches it.
Another code-path dropped sign of TIME, presuming all time is positive.
Minds sign now. Patch depends on ChangeSet for 42661.
mysql-test/r/type_time.result:
Show we now no longer ignore sign of TIME-type
in this code-path.
mysql-test/t/type_time.test:
Show we now no longer ignore sign of TIME-type
in this code-path.
sql/item_cmpfunc.cc:
TIME_to_ulonglong() (somewhat obviously) loses sign
of its argument, so we put it back in where needed.
values return too many records
WHERE clauses with "outer_value_list NOT IN subselect" were
handled incorrectly if the outer value list contained multiple
items where at least one of these could be NULL. The first
outer record with NULL value was handled correctly, but if a
second record with NULL value existed, the optimizer would
choose to reuse the result it got on the last execution of the
subselect. This is incorrect if the outer value list has
multiple items.
The fix is to make Item_in_optimizer::val_int (in
item_cmpfunc.cc) reuse the result of the latest execution
for NULL values only if all values in the outer_value_list
are NULL.
mysql-test/r/subselect3.result:
Added test for BUG#48177
mysql-test/t/subselect3.test:
Added test for BUG#48177
sql/item_cmpfunc.cc:
Make Item_in_optimizer::val_int (in item_cmpfunc.cc) reuse the result of the latest execution for NULL values only if all values in the outer_value_list are NULL.
values return too many records
WHERE clauses with "outer_value_list NOT IN subselect" were
handled incorrectly if the outer value list contained multiple
items where at least one of these could be NULL. The first
outer record with NULL value was handled correctly, but if a
second record with NULL value existed, the optimizer would
choose to reuse the result it got on the last execution of the
subselect. This is incorrect if the outer value list has
multiple items.
The fix is to make Item_in_optimizer::val_int (in
item_cmpfunc.cc) reuse the result of the latest execution
for NULL values only if all values in the outer_value_list
are NULL.
When a query was using a DATE or DATETIME value formatted
using any other separator characters beside hyphen '-', a
query with a greater-or-equal '>=' condition matching only
the greatest value in an indexed column, the result was
empty if index range scan was employed.
The range optimizer got a new feature between 5.1.38 and
5.1.39 that changes a greater-or-equal condition to a
greater-than if the value matching that in the query was not
present in the table. But the value comparison function
compared the dates as strings instead of dates.
The bug was fixed by splitting the function
get_date_from_str in two: One part that parses and does
error checking. This function is now visible outside the
module. The old get_date_from_str now calls the new
function.
mysql-test/r/range.result:
Bug#47925: Test result
mysql-test/t/range.test:
Bug#47925: Test case
sql/item.cc:
Bug#47925: Fix + some edit on the comments
sql/item.h:
Bug#47925: Changed function signature
sql/item_cmpfunc.cc:
Bug#47925: Split function in two
sql/item_cmpfunc.h:
Bug#47925: Declaration of new function
sql/opt_range.cc:
Bug#47925: Added THD to function call
sql/time.cc:
Bug#47925: Added microsecond comparison
When a query was using a DATE or DATETIME value formatted
using any other separator characters beside hyphen '-', a
query with a greater-or-equal '>=' condition matching only
the greatest value in an indexed column, the result was
empty if index range scan was employed.
The range optimizer got a new feature between 5.1.38 and
5.1.39 that changes a greater-or-equal condition to a
greater-than if the value matching that in the query was not
present in the table. But the value comparison function
compared the dates as strings instead of dates.
The bug was fixed by splitting the function
get_date_from_str in two: One part that parses and does
error checking. This function is now visible outside the
module. The old get_date_from_str now calls the new
function.
The SE API requires mysql to notify the storage engine that
it's going to read certain tables at the beginning of the
statement (by calling start_stmt(), store_lock() or
external_lock()).
These are typically called by the lock_tables().
However SHOW CREATE TABLE is not pre-locking the tables
because it's not expected to access the data at all.
But for some view definitions (that include comparing a
date/datetime/timestamp column to a string returning
scalar subquery) the JOIN::prepare may still access data
when materializing the scalar non-correlated subquery
in Arg_comparator::can_compare_as_dates().
Fixed by not materializing the subquery when the function
is called in a SHOW/EXPLAIN/CREATE VIEW
The SE API requires mysql to notify the storage engine that
it's going to read certain tables at the beginning of the
statement (by calling start_stmt(), store_lock() or
external_lock()).
These are typically called by the lock_tables().
However SHOW CREATE TABLE is not pre-locking the tables
because it's not expected to access the data at all.
But for some view definitions (that include comparing a
date/datetime/timestamp column to a string returning
scalar subquery) the JOIN::prepare may still access data
when materializing the scalar non-correlated subquery
in Arg_comparator::can_compare_as_dates().
Fixed by not materializing the subquery when the function
is called in a SHOW/EXPLAIN/CREATE VIEW
SELECT ... WHERE ... IN (NULL, ...) does full table scan,
even if the same query without the NULL uses efficient range scan.
The bugfix for the bug 18360 introduced an optimization:
if
1) all right-hand arguments of the IN function are constants
2) result types of all right argument items are compatible
enough to use the same single comparison function to
compare all of them to the left argument,
then
we can convert the right-hand list of constant items to an array
of equally-typed constant values for the further
QUICK index access etc. (see Item_func_in::fix_length_and_dec()).
The Item_null constant item objects have STRING_RESULT
result types, so, as far as Item_func_in::fix_length_and_dec()
is aware of NULLs in the right list, this improvement efficiently
optimizes IN function calls with a mixed right list of NULLs and
string constants. However, the optimization doesn't affect mixed
lists of NULLs and integers, floats etc., because there is no
unique common comparator.
New optimization has been added to ignore the result type
of NULL constants in the static analysis of mixed right-hand lists.
This is safe, because at the execution phase we care about
presence of NULLs anyway.
1. The collect_cmp_types() function has been modified to optionally
ignore NULL constants in the item list.
2. NULL-skipping code of the Item_func_in::fix_length_and_dec()
function has been modified to work not only with in_string
vectors but with in_vectors of other types.
mysql-test/r/func_in.result:
Added test case for the bug #44139.
mysql-test/t/func_in.test:
Added test case for the bug #44139.
sql/item_cmpfunc.cc:
Bug #44139: Table scan when NULL appears in IN clause
1. The collect_cmp_types() function has been modified to optionally
ignore NULL constants in the item list.
2. NULL-skipping code of the Item_func_in::fix_length_and_dec()
function has been modified to work not only with in_string
vectors but with in_vectors of other types.
SELECT ... WHERE ... IN (NULL, ...) does full table scan,
even if the same query without the NULL uses efficient range scan.
The bugfix for the bug 18360 introduced an optimization:
if
1) all right-hand arguments of the IN function are constants
2) result types of all right argument items are compatible
enough to use the same single comparison function to
compare all of them to the left argument,
then
we can convert the right-hand list of constant items to an array
of equally-typed constant values for the further
QUICK index access etc. (see Item_func_in::fix_length_and_dec()).
The Item_null constant item objects have STRING_RESULT
result types, so, as far as Item_func_in::fix_length_and_dec()
is aware of NULLs in the right list, this improvement efficiently
optimizes IN function calls with a mixed right list of NULLs and
string constants. However, the optimization doesn't affect mixed
lists of NULLs and integers, floats etc., because there is no
unique common comparator.
New optimization has been added to ignore the result type
of NULL constants in the static analysis of mixed right-hand lists.
This is safe, because at the execution phase we care about
presence of NULLs anyway.
1. The collect_cmp_types() function has been modified to optionally
ignore NULL constants in the item list.
2. NULL-skipping code of the Item_func_in::fix_length_and_dec()
function has been modified to work not only with in_string
vectors but with in_vectors of other types.
with gcc 4.3.2
This patch fixes a number of GCC warnings about variables used
before initialized. A new macro UNINIT_VAR() is introduced for
use in the variable declaration, and LINT_INIT() usage will be
gradually deprecated. (A workaround is used for g++, pending a
patch for a g++ bug.)
GCC warnings for unused results (attribute warn_unused_result)
for a number of system calls (present at least in later
Ubuntus, where the usual void cast trick doesn't work) are
also fixed.
client/mysqlmanager-pwgen.c:
A fix for warn_unused_result, adding fallback to use of
srand()/rand() if /dev/random cannot be used. Also actually
adds calls to rand() in the second branch so that it actually
creates a random password.
with gcc 4.3.2
This patch fixes a number of GCC warnings about variables used
before initialized. A new macro UNINIT_VAR() is introduced for
use in the variable declaration, and LINT_INIT() usage will be
gradually deprecated. (A workaround is used for g++, pending a
patch for a g++ bug.)
GCC warnings for unused results (attribute warn_unused_result)
for a number of system calls (present at least in later
Ubuntus, where the usual void cast trick doesn't work) are
also fixed.
The problem was that creating a DECIMAL column from a decimal
value could lead to a failed assertion as decimal values can
have a higher precision than those attached to a table. The
assert could be triggered by creating a table from a decimal
with a large (> 30) scale. Also, there was a problem in
calculating the number of digits in the integral and fractional
parts if both exceeded the maximum number of digits permitted
by the new decimal type.
The solution is to ensure that truncation procedure is executed
when deducing a DECIMAL column from a decimal value of higher
precision. If the integer part is equal to or bigger than the
maximum precision for the DECIMAL type (65), the integer part
is truncated to fit and the fractional becomes zero. Otherwise,
the fractional part is truncated to fit into the space left
after the integer part is copied.
This patch borrows code and ideas from Martin Hansson's patch.
mysql-test/r/type_newdecimal.result:
Add test case result for Bug#45261. Also, update test case to
reflect that an additive operation increases the precision of
the resulting type by 1.
mysql-test/t/type_newdecimal.test:
Add test case for Bug#45261
sql/field.cc:
Added DBUG_ASSERT to ensure object's invariant is maintained.
Implement method to create a field to hold a decimal value
from an item.
sql/field.h:
Explain member variable. Add method to create a new decimal field.
sql/item.cc:
The precision should only be capped when storing the value
on a table. Also, this makes it impossible to calculate the
integer part if Item::decimals (the scale) is larger than the
precision.
sql/item.h:
Simplify calculation of integer part.
sql/item_cmpfunc.cc:
Do not limit the precision. It will be capped later.
sql/item_func.cc:
Use new method for allocating a new decimal field.
Add a specialized method for retrieving the precision
of a user variable item.
sql/item_func.h:
Add method to return the precision of a user variable.
sql/item_sum.cc:
Use new method for allocating a new decimal field.
sql/my_decimal.h:
The integer part could be improperly calculated for a decimal
with 31 digits in the fractional part.
sql/sql_select.cc:
Use new method which truncates the integer or decimal parts
as needed.
The problem was that creating a DECIMAL column from a decimal
value could lead to a failed assertion as decimal values can
have a higher precision than those attached to a table. The
assert could be triggered by creating a table from a decimal
with a large (> 30) scale. Also, there was a problem in
calculating the number of digits in the integral and fractional
parts if both exceeded the maximum number of digits permitted
by the new decimal type.
The solution is to ensure that truncation procedure is executed
when deducing a DECIMAL column from a decimal value of higher
precision. If the integer part is equal to or bigger than the
maximum precision for the DECIMAL type (65), the integer part
is truncated to fit and the fractional becomes zero. Otherwise,
the fractional part is truncated to fit into the space left
after the integer part is copied.
This patch borrows code and ideas from Martin Hansson's patch.